1
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Kazazian K, Edlow BL, Owen AM. Detecting awareness after acute brain injury. Lancet Neurol 2024; 23:836-844. [PMID: 39030043 DOI: 10.1016/s1474-4422(24)00209-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/28/2024] [Accepted: 05/07/2024] [Indexed: 07/21/2024]
Abstract
Advances over the past two decades in functional neuroimaging have provided new diagnostic and prognostic tools for patients with severe brain injury. Some of the most pertinent developments in this area involve the assessment of residual brain function in patients in the intensive care unit during the acute phase of severe injury, when they are at their most vulnerable and prognosis is uncertain. Advanced neuroimaging techniques, such as functional MRI and EEG, have now been used to identify preserved cognitive processing, including covert conscious awareness, and to relate them to outcome in patients who are behaviourally unresponsive. Yet, technical and logistical challenges to clinical integration of these advanced neuroimaging techniques remain, such as the need for specialised expertise to acquire, analyse, and interpret data and to determine the appropriate timing for such assessments. Once these barriers are overcome, advanced functional neuroimaging technologies could improve diagnosis and prognosis for millions of patients worldwide.
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Affiliation(s)
- Karnig Kazazian
- Western Institute of Neuroscience, Western University, London, ON, Canada.
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA; Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA
| | - Adrian M Owen
- Western Institute of Neuroscience, Western University, London, ON, Canada; Department of Physiology and Pharmacology and Department of Psychology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
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2
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Young MJ, Kazazian K, Fischer D, Lissak IA, Bodien YG, Edlow BL. Disclosing Results of Tests for Covert Consciousness: A Framework for Ethical Translation. Neurocrit Care 2024; 40:865-878. [PMID: 38243150 PMCID: PMC11147696 DOI: 10.1007/s12028-023-01899-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/22/2023] [Indexed: 01/21/2024]
Abstract
The advent of neurotechnologies including advanced functional magnetic resonance imaging and electroencephalography to detect states of awareness not detectable by traditional bedside neurobehavioral techniques (i.e., covert consciousness) promises to transform neuroscience research and clinical practice for patients with brain injury. As these interventions progress from research tools into actionable, guideline-endorsed clinical tests, ethical guidance for clinicians on how to responsibly communicate the sensitive results they yield is crucial yet remains underdeveloped. Drawing on insights from empirical and theoretical neuroethics research and our clinical experience with advanced neurotechnologies to detect consciousness in behaviorally unresponsive patients, we critically evaluate ethical promises and perils associated with disclosing the results of clinical covert consciousness assessments and describe a semistructured approach to responsible data sharing to mitigate potential risks.
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Affiliation(s)
- Michael J Young
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA, 02114, USA.
| | - Karnig Kazazian
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA, 02114, USA
- Western Institute of Neuroscience, Western University, London, ON, Canada
| | - David Fischer
- University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - India A Lissak
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA, 02114, USA
| | - Yelena G Bodien
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA, 02114, USA
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA, 02114, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
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3
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Shen J, Sun J, Zhang Z, Sun B, Li H, Liu Y. The Effect of Hearing Loss and Working Memory Capacity on Context Use and Reliance on Context in Older Adults. Ear Hear 2024; 45:787-800. [PMID: 38273447 DOI: 10.1097/aud.0000000000001470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2024]
Abstract
OBJECTIVES Older adults often complain of difficulty in communicating in noisy environments. Contextual information is considered an important cue for identifying everyday speech. To date, it has not been clear exactly how context use (CU) and reliance on context in older adults are affected by hearing status and cognitive function. The present study examined the effects of semantic context on the performance of speech recognition, recall, perceived listening effort (LE), and noise tolerance, and further explored the impacts of hearing loss and working memory capacity on CU and reliance on context among older adults. DESIGN Fifty older adults with normal hearing and 56 older adults with mild-to-moderate hearing loss between the ages of 60 and 95 years participated in this study. A median split of the backward digit span further classified the participants into high working memory (HWM) and low working memory (LWM) capacity groups. Each participant performed high- and low-context Repeat and Recall tests, including a sentence repeat and delayed recall task, subjective assessments of LE, and tolerable time under seven signal to noise ratios (SNRs). CU was calculated as the difference between high- and low-context sentences for each outcome measure. The proportion of context use (PCU) in high-context performance was taken as the reliance on context to explain the degree to which participants relied on context when they repeated and recalled high-context sentences. RESULTS Semantic context helps improve the performance of speech recognition and delayed recall, reduces perceived LE, and prolongs noise tolerance in older adults with and without hearing loss. In addition, the adverse effects of hearing loss on the performance of repeat tasks were more pronounced in low context than in high context, whereas the effects on recall tasks and noise tolerance time were more significant in high context than in low context. Compared with other tasks, the CU and PCU in repeat tasks were more affected by listening status and working memory capacity. In the repeat phase, hearing loss increased older adults' reliance on the context of a relatively challenging listening environment, as shown by the fact that when the SNR was 0 and -5 dB, the PCU (repeat) of the hearing loss group was significantly greater than that of the normal-hearing group, whereas there was no significant difference between the two hearing groups under the remaining SNRs. In addition, older adults with LWM had significantly greater CU and PCU in repeat tasks than those with HWM, especially at SNRs with moderate task demands. CONCLUSIONS Taken together, semantic context not only improved speech perception intelligibility but also released cognitive resources for memory encoding in older adults. Mild-to-moderate hearing loss and LWM capacity in older adults significantly increased the use and reliance on semantic context, which was also modulated by the level of SNR.
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Affiliation(s)
- Jiayuan Shen
- School of Medical Technology and Information Engineering, Zhejiang Chinese Medical University, Zhejiang, China
| | - Jiayu Sun
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Zhikai Zhang
- Department of Otolaryngology, Head and Neck Surgery, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Baoxuan Sun
- Training Department, Widex Hearing Aid (Shanghai) Co., Ltd, Shanghai, China
| | - Haitao Li
- Department of Neurology, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- These authors contributed equally to this work and are co-corresponding authors
| | - Yuhe Liu
- Department of Otolaryngology, Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
- These authors contributed equally to this work and are co-corresponding authors
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Young MJ, Fecchio M, Bodien YG, Edlow BL. Covert cortical processing: a diagnosis in search of a definition. Neurosci Conscious 2024; 2024:niad026. [PMID: 38327828 PMCID: PMC10849751 DOI: 10.1093/nc/niad026] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/22/2023] [Accepted: 12/10/2023] [Indexed: 02/09/2024] Open
Abstract
Historically, clinical evaluation of unresponsive patients following brain injury has relied principally on serial behavioral examination to search for emerging signs of consciousness and track recovery. Advances in neuroimaging and electrophysiologic techniques now enable clinicians to peer into residual brain functions even in the absence of overt behavioral signs. These advances have expanded clinicians' ability to sub-stratify behaviorally unresponsive and seemingly unaware patients following brain injury by querying and classifying covert brain activity made evident through active or passive neuroimaging or electrophysiologic techniques, including functional MRI, electroencephalography (EEG), transcranial magnetic stimulation-EEG, and positron emission tomography. Clinical research has thus reciprocally influenced clinical practice, giving rise to new diagnostic categories including cognitive-motor dissociation (i.e. 'covert consciousness') and covert cortical processing (CCP). While covert consciousness has received extensive attention and study, CCP is relatively less understood. We describe that CCP is an emerging and clinically relevant state of consciousness marked by the presence of intact association cortex responses to environmental stimuli in the absence of behavioral evidence of stimulus processing. CCP is not a monotonic state but rather encapsulates a spectrum of possible association cortex responses from rudimentary to complex and to a range of possible stimuli. In constructing a roadmap for this evolving field, we emphasize that efforts to inform clinicians, philosophers, and researchers of this condition are crucial. Along with strategies to sensitize diagnostic criteria and disorders of consciousness nosology to these vital discoveries, democratizing access to the resources necessary for clinical identification of CCP is an emerging clinical and ethical imperative.
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Affiliation(s)
- Michael J Young
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
| | - Matteo Fecchio
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
| | - Yelena G Bodien
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, 300 1st Ave, Charlestown, Boston, MA 02129, USA
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Charlestown, Charlestown, MA 02129, USA
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Tauber JM, Brincat SL, Stephen EP, Donoghue JA, Kozachkov L, Brown EN, Miller EK. Propofol-mediated Unconsciousness Disrupts Progression of Sensory Signals through the Cortical Hierarchy. J Cogn Neurosci 2024; 36:394-413. [PMID: 37902596 PMCID: PMC11161138 DOI: 10.1162/jocn_a_02081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
A critical component of anesthesia is the loss of sensory perception. Propofol is the most widely used drug for general anesthesia, but the neural mechanisms of how and when it disrupts sensory processing are not fully understood. We analyzed local field potential and spiking recorded from Utah arrays in auditory cortex, associative cortex, and cognitive cortex of nonhuman primates before and during propofol-mediated unconsciousness. Sensory stimuli elicited robust and decodable stimulus responses and triggered periods of stimulus-related synchronization between brain areas in the local field potential of Awake animals. By contrast, propofol-mediated unconsciousness eliminated stimulus-related synchrony and drastically weakened stimulus responses and information in all brain areas except for auditory cortex, where responses and information persisted. However, we found stimuli occurring during spiking Up states triggered weaker spiking responses than in Awake animals in auditory cortex, and little or no spiking responses in higher order areas. These results suggest that propofol's effect on sensory processing is not just because of asynchronous Down states. Rather, both Down states and Up states reflect disrupted dynamics.
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Affiliation(s)
- John M Tauber
- Massachusetts Institute of Technology, Cambridge, MA
| | | | | | | | - Leo Kozachkov
- Massachusetts Institute of Technology, Cambridge, MA
| | - Emery N Brown
- Massachusetts Institute of Technology, Cambridge, MA
- Massachusetts General Hospital, Boston
- Harvard University, Cambridge, MA
| | - Earl K Miller
- Massachusetts Institute of Technology, Cambridge, MA
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6
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Kosakowski HL, Norman-Haignere S, Mynick A, Takahashi A, Saxe R, Kanwisher N. Preliminary evidence for selective cortical responses to music in one-month-old infants. Dev Sci 2023; 26:e13387. [PMID: 36951215 DOI: 10.1111/desc.13387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 02/17/2023] [Accepted: 02/21/2023] [Indexed: 03/24/2023]
Abstract
Prior studies have observed selective neural responses in the adult human auditory cortex to music and speech that cannot be explained by the differing lower-level acoustic properties of these stimuli. Does infant cortex exhibit similarly selective responses to music and speech shortly after birth? To answer this question, we attempted to collect functional magnetic resonance imaging (fMRI) data from 45 sleeping infants (2.0- to 11.9-weeks-old) while they listened to monophonic instrumental lullabies and infant-directed speech produced by a mother. To match acoustic variation between music and speech sounds we (1) recorded music from instruments that had a similar spectral range as female infant-directed speech, (2) used a novel excitation-matching algorithm to match the cochleagrams of music and speech stimuli, and (3) synthesized "model-matched" stimuli that were matched in spectrotemporal modulation statistics to (yet perceptually distinct from) music or speech. Of the 36 infants we collected usable data from, 19 had significant activations to sounds overall compared to scanner noise. From these infants, we observed a set of voxels in non-primary auditory cortex (NPAC) but not in Heschl's Gyrus that responded significantly more to music than to each of the other three stimulus types (but not significantly more strongly than to the background scanner noise). In contrast, our planned analyses did not reveal voxels in NPAC that responded more to speech than to model-matched speech, although other unplanned analyses did. These preliminary findings suggest that music selectivity arises within the first month of life. A video abstract of this article can be viewed at https://youtu.be/c8IGFvzxudk. RESEARCH HIGHLIGHTS: Responses to music, speech, and control sounds matched for the spectrotemporal modulation-statistics of each sound were measured from 2- to 11-week-old sleeping infants using fMRI. Auditory cortex was significantly activated by these stimuli in 19 out of 36 sleeping infants. Selective responses to music compared to the three other stimulus classes were found in non-primary auditory cortex but not in nearby Heschl's Gyrus. Selective responses to speech were not observed in planned analyses but were observed in unplanned, exploratory analyses.
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Affiliation(s)
- Heather L Kosakowski
- Department of Brain and Cognitive Sciences, Massachusetts Institute, of Technology, Cambridge, Massachusetts, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Center for Brains, Minds and Machines, Cambridge, Massachusetts, USA
| | | | - Anna Mynick
- Psychological and Brain Sciences, Dartmouth College, Hannover, New Hampshire, USA
| | - Atsushi Takahashi
- Department of Brain and Cognitive Sciences, Massachusetts Institute, of Technology, Cambridge, Massachusetts, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rebecca Saxe
- Department of Brain and Cognitive Sciences, Massachusetts Institute, of Technology, Cambridge, Massachusetts, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Center for Brains, Minds and Machines, Cambridge, Massachusetts, USA
| | - Nancy Kanwisher
- Department of Brain and Cognitive Sciences, Massachusetts Institute, of Technology, Cambridge, Massachusetts, USA
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Center for Brains, Minds and Machines, Cambridge, Massachusetts, USA
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7
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Tauber JM, Brincat SL, Stephen EP, Donaghue JA, Kozachkov L, Brown EN, Miller EK. Propofol Mediated Unconsciousness Disrupts Progression of Sensory Signals through the Cortical Hierarchy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.25.546463. [PMID: 37425684 PMCID: PMC10327085 DOI: 10.1101/2023.06.25.546463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
A critical component of anesthesia is the loss sensory perception. Propofol is the most widely used drug for general anesthesia, but the neural mechanisms of how and when it disrupts sensory processing are not fully understood. We analyzed local field potential (LFP) and spiking recorded from Utah arrays in auditory cortex, associative cortex, and cognitive cortex of non-human primates before and during propofol mediated unconsciousness. Sensory stimuli elicited robust and decodable stimulus responses and triggered periods of stimulus-induced coherence between brain areas in the LFP of awake animals. By contrast, propofol mediated unconsciousness eliminated stimulus-induced coherence and drastically weakened stimulus responses and information in all brain areas except for auditory cortex, where responses and information persisted. However, we found stimuli occurring during spiking Up states triggered weaker spiking responses than in awake animals in auditory cortex, and little or no spiking responses in higher order areas. These results suggest that propofol's effect on sensory processing is not just due to asynchronous down states. Rather, both Down states and Up states reflect disrupted dynamics.
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Affiliation(s)
- John M. Tauber
- The Picower Institute for Learning & Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Institute for Data, Systems, and Society, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Scott L. Brincat
- The Picower Institute for Learning & Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Emily P. Stephen
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA
| | - Jacob A. Donaghue
- The Picower Institute for Learning & Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Leo Kozachkov
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Emery N. Brown
- The Picower Institute for Learning & Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Institute for Data, Systems, and Society, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Department of Anesthesia, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Earl K. Miller
- The Picower Institute for Learning & Memory, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
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8
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Marmelshtein A, Eckerling A, Hadad B, Ben-Eliyahu S, Nir Y. Sleep-like changes in neural processing emerge during sleep deprivation in early auditory cortex. Curr Biol 2023:S0960-9822(23)00773-X. [PMID: 37385257 DOI: 10.1016/j.cub.2023.06.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 03/30/2023] [Accepted: 06/07/2023] [Indexed: 07/01/2023]
Abstract
Insufficient sleep is commonplace in modern lifestyle and can lead to grave outcomes, yet the changes in neuronal activity accumulating over hours of extended wakefulness remain poorly understood. Specifically, which aspects of cortical processing are affected by sleep deprivation (SD), and whether they also affect early sensory regions, remain unclear. Here, we recorded spiking activity in the rat auditory cortex along with polysomnography while presenting sounds during SD followed by recovery sleep. We found that frequency tuning, onset responses, and spontaneous firing rates were largely unaffected by SD. By contrast, SD decreased entrainment to rapid (≥20 Hz) click trains, increased population synchrony, and increased the prevalence of sleep-like stimulus-induced silent periods, even when ongoing activity was similar. Recovery NREM sleep was associated with similar effects as SD with even greater magnitude, while auditory processing during REM sleep was similar to vigilant wakefulness. Our results show that processes akin to those in NREM sleep invade the activity of cortical circuits during SD, even in the early sensory cortex.
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Affiliation(s)
- Amit Marmelshtein
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Anabel Eckerling
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; School of Psychological Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Barak Hadad
- School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shamgar Ben-Eliyahu
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; School of Psychological Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yuval Nir
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel; The Sieratzki-Sagol Center for Sleep Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel.
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9
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Johnson KR, Temeyer JP, Schulte PJ, Nydahl P, Philbrick KL, Karnatovskaia LV. Aloud real- time reading of intensive care unit diaries: A feasibility study. Intensive Crit Care Nurs 2023; 76:103400. [PMID: 36706496 DOI: 10.1016/j.iccn.2023.103400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 01/10/2023] [Accepted: 01/18/2023] [Indexed: 01/27/2023]
Abstract
OBJECTIVES Memories of frightening/delusional intensive care unit experiences are a major risk factor for subsequent psychiatric morbidity of critical illness survivors; factual memories are protective. Systematically providing factual information during initial memory consolidation could mitigate the emotional character of the formed memories. We explored feasibility and obtained stakeholder feedback of a novel approach to intensive care unit diaries whereby entries were read aloud to the patients right after they were written to facilitate systematic real time orientation and formation of factual memories. RESEARCH METHODOLOGY Prospective interventional pilot study involving reading diary entries aloud. We have also interviewed involved stakeholders for feedback and collected exploratory data on psychiatric symptoms from patients right after the intensive care stay. SETTING Various intensive care units in a single academic center. MAIN OUTCOME MEASURES Feasibility was defined as intervention delivery on ≥80% of days following patient recruitment. Content analysis was performed on stakeholder interview responses. Questionnaire data were compared for patients who received real-time reading to the historical cohort who did not. RESULTS Overall, 57% (17 of 30) of patients achieved the set feasibility threshold. Following protocol adjustment, we achieved 86% feasibility in the last subset of patients. Patients reported the intervention as comforting and appreciated the reorientation aspect. Nurses overwhelmingly liked the idea; most common concern was not knowing what to write. Some therapists were unsure whether reading entries aloud might overwhelm the patients. There were no significant differences in psychiatric symptoms when compared to the historic cohort. CONCLUSION We encountered several implementation obstacles; once these were addressed, we achieved set feasibility target for the last group of patients. Reading diary entries aloud was welcomed by stakeholders. Designing a trial to assess efficacy of the intervention on psychiatric outcomes appears warranted. IMPLICATIONS FOR CLINICAL PRACTICE There is no recommendation to change current practice as benefits of the intervention are unproven.
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Affiliation(s)
- Kimberly R Johnson
- Department of Pulmonary and Critical Care, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.
| | - Joseph P Temeyer
- Department of Nursing, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Phillip J Schulte
- Department of Biostatistics, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
| | - Peter Nydahl
- Department of Anesthesia and Critical Care, Arnold-Heller-Str. 3, University Hospital Schleswig-Holstein, Kiel 24105, Germany
| | - Kemuel L Philbrick
- Department of Psychiatry and Psychology, 200 First St SW, Mayo Clinic, Rochester, MN 55905, USA
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10
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Norton L, Kazazian K, Gofton T, Debicki DB, Fernandez-Espejo D, Peelle JE, Al Thenayan E, Young GB, Owen AM. Functional Neuroimaging as an Assessment Tool in Critically Ill Patients. Ann Neurol 2023; 93:131-141. [PMID: 36222470 DOI: 10.1002/ana.26530] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 09/29/2022] [Accepted: 10/05/2022] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Little is known about residual cognitive function in the earliest stages of serious brain injury. Functional neuroimaging has yielded valuable diagnostic and prognostic information in chronic disorders of consciousness, such as the vegetative state (also termed unresponsive wakefulness syndrome). The objective of the current study was to determine if functional neuroimaging could be efficacious in the assessment of cognitive function in acute disorders of consciousness, such as coma, where decisions about the withdrawal of life-sustaining therapies are often made. METHODS A hierarchical functional magnetic resonance imaging (fMRI) approach assessed sound perception, speech perception, language comprehension, and covert command following in 17 critically ill patients admitted to the intensive care unit (ICU). RESULTS Preserved auditory function was observed in 15 patients (88%), whereas 5 (29%) also had preserved higher-order language comprehension. Notably, one patient could willfully modulate his brain activity when instructed to do so, suggesting a level of covert conscious awareness that was entirely inconsistent with his clinical diagnosis at the time of the scan. Across patients, a positive relationship was also observed between fMRI responsivity and the level of functional recovery, such that patients with the greatest functional recovery had neural responses most similar to those observed in healthy control participants. INTERPRETATION These results suggest that fMRI may provide important diagnostic and prognostic information beyond standard clinical assessment in acutely unresponsive patients, which may aid discussions surrounding the continuation or removal of life-sustaining therapies during the early post-injury period. ANN NEUROL 2023;93:131-141.
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Affiliation(s)
- Loretta Norton
- Brain and Mind Institute, Western University, London, Ontario, Canada.,Department of Psychology, King's University College at Western University, London, Ontario, Canada
| | - Karnig Kazazian
- Brain and Mind Institute, Western University, London, Ontario, Canada
| | - Teneille Gofton
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Derek B Debicki
- Brain and Mind Institute, Western University, London, Ontario, Canada.,Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Davinia Fernandez-Espejo
- School of Psychology, University of Birmingham, Edgbaston, Birmingham, UK.,Centre for Human Brain Health and School of Psychology, University of Birmingham, Edgbaston, Birmingham, UK
| | - Jonathan E Peelle
- Center for Cognitive and Brain Health, Northeastern University, Boston, MA, USA
| | - Eyad Al Thenayan
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - G Bryan Young
- Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Adrian M Owen
- Brain and Mind Institute, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology and Department of Psychology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
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11
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Zheng RZ, Xu CX, Zhou LY, Feng DF. Default mode network overshadow executive control network in coma emergence and awakening prediction of patients with sTBI. Neuroimage Clin 2023; 37:103361. [PMID: 36871404 PMCID: PMC9995458 DOI: 10.1016/j.nicl.2023.103361] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/12/2023] [Accepted: 02/24/2023] [Indexed: 03/06/2023]
Abstract
OBJECTIVE We aimed to explore the pathogenesis of traumatic coma related to functional connectivity (FC) within the default mode network (DMN), within the executive control network (ECN) and between the DMN and ECN and to investigate its capacity for predicting awakening. METHODS We carried out resting-state functional magnetic resonance imaging (fMRI) examinations on 28 traumatic coma patients and 28 age-matched healthy controls. DMN and ECN nodes were split into regions of interest (ROIs), and node-to-node FC analysis was conducted on individual participants. To identify coma pathogenesis, we compared the pairwise FC differences between coma patients and healthy controls. Meanwhile, we divided the traumatic coma patients into different subgroups based on their clinical outcome scores at 6 months postinjury. Considering the awakening prediction, we calculated the area under the curve (AUC) to evaluate the predictive ability of changed FC pairs. RESULTS We found a massive pairwise FC alteration in the patients with traumatic coma compared to the healthy controls [45% (33/74) pairwise FC located in the DMN, 27% (20/74) pairwise FC located in the ECN, and 28% (21/74) pairwise FC located between the DMN and ECN]. Moreover, in the awake and coma groups, there were 67% (12/18) pairwise FC alterations located in the DMN and 33% (6/18) pairwise FC alterations located between the DMN and ECN. We also indicated that pairwise FC that showed a predictive value of 6-month awakening was mainly located in the DMN rather than in the ECN. Specifically, decreased FC between the right superior frontal gyrus and right parahippocampal gyrus (in the DMN) showed the highest predictive ability (AUC = 0.827). CONCLUSION In the acute phase of severe traumatic brain injury (sTBI), the DMN plays a more prominent role than the ECN and the DMN-ECN interaction in the emergence of traumatic coma and the prediction of 6-month awakening.
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Affiliation(s)
- Rui-Zhe Zheng
- Department of Neurosurgery, Southern Medical University Affiliated Fengxian Hospital, Shanghai, China; Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Can-Xin Xu
- Department of Neurosurgery, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai, China
| | - Lai-Yang Zhou
- School of Preclinical Medicine, Wannan Medical College, Wuhu, Anhui, China
| | - Dong-Fu Feng
- Department of Neurosurgery, Southern Medical University Affiliated Fengxian Hospital, Shanghai, China; Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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12
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Bergman L, Krom AJ, Sela Y, Marmelshtein A, Hayat H, Regev N, Nir Y. Propofol anesthesia concentration rather than abrupt behavioral unresponsiveness linearly degrades responses in the rat primary auditory cortex. Cereb Cortex 2022; 32:5005-5019. [PMID: 35169834 DOI: 10.1093/cercor/bhab528] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 12/27/2022] Open
Abstract
Despite extensive knowledge of its molecular and cellular effects, how anesthesia affects sensory processing remains poorly understood. In particular, it remains unclear whether anesthesia modestly or robustly degrades activity in primary sensory regions, and whether such changes are linked to anesthesia drug concentration versus behavioral unresponsiveness, which are typically confounded. Here, we used slow gradual intravenous propofol anesthesia induction together with auditory stimulation and intermittent assessment of behavioral responsiveness while recording epidural electroencephalogram, and neuronal spiking activity in primary auditory cortex (PAC) of eight rats. We found that all main components of neuronal activity including spontaneous firing rates, onset response magnitudes, onset response latencies, postonset neuronal silence duration, late-locking to 40 Hz click-trains, and offset responses, gradually changed in a dose-dependent manner with increasing anesthesia levels without showing abrupt shifts around loss of righting reflex or other time-points. Thus, the dominant factor affecting PAC responses is the anesthesia drug concentration rather than any sudden, dichotomous behavioral state changes. Our findings explain a wide array of seemingly conflicting results in the literature that, depending on the precise definition of wakefulness (vigilant vs. drowsy) and anesthesia (light vs. deep/surgical), report a spectrum of effects in primary regions ranging from minimal to dramatic differences.
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Affiliation(s)
- Lottem Bergman
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.,Department of Neurosurgery, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel
| | - Aaron J Krom
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.,Department of Anesthesiology and Critical Care Medicine, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel.,Department of Anesthesiology and Critical Care Medicine, Hadassah Medical Organization, Jerusalem 91120, Israel
| | - Yaniv Sela
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Amit Marmelshtein
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Hanna Hayat
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Noa Regev
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yuval Nir
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.,The Sieratzki-Sagol Center for Sleep Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel.,Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
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13
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Castellucci GA, Guenther FH, Long MA. A Theoretical Framework for Human and Nonhuman Vocal Interaction. Annu Rev Neurosci 2022; 45:295-316. [PMID: 35316612 PMCID: PMC9909589 DOI: 10.1146/annurev-neuro-111020-094807] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vocal communication is a critical feature of social interaction across species; however, the relation between such behavior in humans and nonhumans remains unclear. To enable comparative investigation of this topic, we review the literature pertinent to interactive language use and identify the superset of cognitive operations involved in generating communicative action. We posit these functions comprise three intersecting multistep pathways: (a) the Content Pathway, which selects the movements constituting a response; (b) the Timing Pathway, which temporally structures responses; and (c) the Affect Pathway, which modulates response parameters according to internal state. These processing streams form the basis of the Convergent Pathways for Interaction framework, which provides a conceptual model for investigating the cognitive and neural computations underlying vocal communication across species.
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Affiliation(s)
- Gregg A. Castellucci
- NYU Neuroscience Institute and Department of Otolaryngology, New York University Langone Medical Center, New York, NY, USA
| | - Frank H. Guenther
- Departments of Speech, Language & Hearing Sciences and Biomedical Engineering, Boston University, Boston, MA, USA
| | - Michael A. Long
- NYU Neuroscience Institute and Department of Otolaryngology, New York University Langone Medical Center, New York, NY, USA
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14
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Abstract
The extent to which we are affected by perceptual input of which we are unaware is widely debated. By measuring neural responses to sensory stimulation, neuroscientific data could complement behavioral results with valuable evidence. Here we review neuroscientific findings of processing of high-level information, as well as interactions with attention and memory. Although the results are mixed, we find initial support for processing object categories and words, possibly to the semantic level, as well as emotional expressions. Robust neural evidence for face individuation and integration of sentences or scenes is lacking. Attention affects the processing of stimuli that are not consciously perceived, and such stimuli may exogenously but not endogenously capture attention when relevant, and be maintained in memory over time. Sources of inconsistency in the literature include variability in control for awareness as well as individual differences, calling for future studies that adopt stricter measures of awareness and probe multiple processes within subjects.
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Affiliation(s)
- Liad Mudrik
- School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel;
| | - Leon Y Deouell
- Department of Psychology and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel;
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15
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Almeida VN. The neural hierarchy of consciousness. Neuropsychologia 2022; 169:108202. [PMID: 35271856 DOI: 10.1016/j.neuropsychologia.2022.108202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/25/2022] [Accepted: 03/01/2022] [Indexed: 01/08/2023]
Abstract
The chief undertaking in the studies of consciousness is that of unravelling "the minimal set of neural processes that are together sufficient for the conscious experience of a particular content - the neural correlates of consciousness". To this day, this crusade remains at an impasse, with a clash of two main theories: consciousness may arise either in a graded and cortically-localised fashion, or in an all-or-none and widespread one. In spite of the long-lasting theoretical debates, neurophysiological theories of consciousness have been mostly dissociated from them. Herein, a theoretical review will be put forth with the aim to change that. In its first half, we will cover the hard available evidence on the neurophysiology of consciousness, whereas in its second half we will weave a series of considerations on both theories and substantiate a novel take on conscious awareness: the levels of processing approach, partitioning the conscious architecture into lower- and higher-order, graded and nonlinear.
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Affiliation(s)
- Victor N Almeida
- Faculdade de Letras, Universidade Federal de Minas Gerais (UFMG), Av. Pres. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
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16
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Linke AC, Slušná D, Kohli JS, Álvarez-Linera Prado J, Müller RA, Hinzen W. Morphometry and functional connectivity of auditory cortex in school-age children with profound language disabilities: Five comparative case studies. Brain Cogn 2021; 155:105822. [PMID: 34837801 DOI: 10.1016/j.bandc.2021.105822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/27/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
Many neurodevelopmental conditions imply absent or severely reduced language capacities at school age. Evidence from functional magnetic resonance imaging is highly limited. We selected a series of five cases scanned with the same fMRI paradigm and the aim of relating individual language profiles onto underlying patterns of functional connectivity (FC) across auditory language cortex: three with neurogenetic syndromes (Coffin-Siris, Landau-Kleffner, and Fragile-X), one with idiopathic intellectual disability, one with autism spectrum disorder (ASD). Compared to both a group with typical development (TD) and a verbal ASD group (total N = 110), they all showed interhemispheric FC below two standard deviations of the TD mean. Children with higher language scores showed higher intrahemispheric FC between Heschl's gyrus and other auditory language regions, as well as an increase of FC during language stimulation compared to rest. An increase of FC in forward vs. reversed speech in the posterior and middle temporal gyri was seen across all cases. The Coffin-Siris case, the most severe, also had the most anomalous FC patterns and showed reduced myelin content, while the Landau-Kleffner case showed reduced cortical thickness. These results suggest potential for neural markers and mechanisms of severe language processing deficits under highly heterogeneous etiological conditions.
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Affiliation(s)
- Annika Carola Linke
- Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, CA, USA.
| | - Dominika Slušná
- Department of Translation and Language Sciences, Campus Poblenou, Pompeu Fabra University, Barcelona 08018, Barcelona, Spain
| | - Jiwandeep Singh Kohli
- Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, CA, USA
| | | | - Ralph-Axel Müller
- Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, CA, USA; San Diego State University/University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA
| | - Wolfram Hinzen
- Department of Translation and Language Sciences, Campus Poblenou, Pompeu Fabra University, Barcelona 08018, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats, ICREA, 08010 Barcelona, Spain
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17
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Coffey BJ, Threlkeld ZD, Foulkes AS, Bodien YG, Edlow BL. Reemergence of the language network during recovery from severe traumatic brain injury: A pilot functional MRI study. Brain Inj 2021; 35:1552-1562. [PMID: 34546806 DOI: 10.1080/02699052.2021.1972455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PRIMARY OBJECTIVE We hypothesized that, in patients with acute severe traumatic brain injury (TBI) who recover basic language function, speech-evoked blood-oxygen-level-dependent (BOLD) functional MRI (fMRI) responses within the canonical language network increase over the first 6 months post-injury. RESEARCH DESIGN We conducted a prospective, longitudinal fMRI pilot study of adults with acute severe TBI admitted to the intensive care unit. We also enrolled age- and sex-matched healthy subjects. METHODS AND PROCEDURES We evaluated BOLD signal in bilateral superior temporal gyrus (STG) and inferior frontal gyrus (IFG) regions of interest acutely and approximately 6 months post-injury. Given evidence that regions outside the canonical language network contribute to language processing, we also performed exploratory whole-brain analyses. MAIN OUTCOMES AND RESULTS Of the 16 patients enrolled, eight returned for follow-up fMRI, all of whom recovered basic language function. We observed speech-evoked longitudinal BOLD increases in the left STG, but not in the right STG, right IFG, or left IFG. Whole-brain analysis revealed increases in the right supramarginal and middle temporal gyri but no differences between patients and healthy subjects (n = 16). CONCLUSION This pilot study suggests that, in patients with severe TBI who recover llanguage function, speech-evoked responses in bihemispheric language-processing cortex reemerge by 6 months post-injury.
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Affiliation(s)
- Brian J Coffey
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology, University of Florida Health, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Zachary D Threlkeld
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology, Stanford University School of Medicine, Stanford, California, USA
| | - Andrea S Foulkes
- Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Yelena G Bodien
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Charlestown, Massachusetts, USA
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA
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18
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Huang Z, Tarnal V, Vlisides PE, Janke EL, McKinney AM, Picton P, Mashour GA, Hudetz AG. Asymmetric neural dynamics characterize loss and recovery of consciousness. Neuroimage 2021; 236:118042. [PMID: 33848623 PMCID: PMC8310457 DOI: 10.1016/j.neuroimage.2021.118042] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/01/2021] [Accepted: 04/04/2021] [Indexed: 02/07/2023] Open
Abstract
Anesthetics are known to disrupt neural interactions in cortical and subcortical brain circuits. While the effect of anesthetic drugs on consciousness is reversible, the neural mechanism mediating induction and recovery may be different. Insight into these distinct mechanisms can be gained from a systematic comparison of neural dynamics during slow induction of and emergence from anesthesia. To this end, we used functional magnetic resonance imaging (fMRI) data obtained in healthy volunteers before, during, and after the administration of propofol at incrementally adjusted target concentrations. We analyzed functional connectivity of corticocortical and subcorticocortical networks and the temporal autocorrelation of fMRI signal as an index of neural processing timescales. We found that en route to unconsciousness, temporal autocorrelation across the entire brain gradually increased, whereas functional connectivity gradually decreased. In contrast, regaining consciousness was associated with an abrupt restoration of cortical but not subcortical temporal autocorrelation and an abrupt boost of subcorticocortical functional connectivity. Pharmacokinetic effects could not account for the difference in neural dynamics between induction and emergence. We conclude that the induction and recovery phases of anesthesia follow asymmetric neural dynamics. A rapid increase in the speed of cortical neural processing and subcorticocortical neural interactions may be a mechanism that reboots consciousness.
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Affiliation(s)
- Zirui Huang
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Corresponding authors. (Z. Huang), (A.G. Hudetz)
| | - Vijay Tarnal
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Phillip E. Vlisides
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ellen L. Janke
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Amy M. McKinney
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Paul Picton
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - George A. Mashour
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anthony G. Hudetz
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA,Corresponding authors. (Z. Huang), (A.G. Hudetz)
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19
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Nourski KV, Steinschneider M, Rhone AE, Krause BM, Mueller RN, Kawasaki H, Banks MI. Cortical Responses to Vowel Sequences in Awake and Anesthetized States: A Human Intracranial Electrophysiology Study. Cereb Cortex 2021; 31:5435-5448. [PMID: 34117741 PMCID: PMC8568007 DOI: 10.1093/cercor/bhab168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/22/2021] [Accepted: 05/22/2021] [Indexed: 02/07/2023] Open
Abstract
Elucidating neural signatures of sensory processing across consciousness states is a major focus in neuroscience. Noninvasive human studies using the general anesthetic propofol reveal differential effects on auditory cortical activity, with a greater impact on nonprimary and auditory-related areas than primary auditory cortex. This study used intracranial electroencephalography to examine cortical responses to vowel sequences during induction of general anesthesia with propofol. Subjects were adult neurosurgical patients with intracranial electrodes placed to identify epileptic foci. Data were collected before electrode removal surgery. Stimuli were vowel sequences presented in a target detection task during awake, sedated, and unresponsive states. Averaged evoked potentials (AEPs) and high gamma (70-150 Hz) power were measured in auditory, auditory-related, and prefrontal cortex. In the awake state, AEPs were found throughout studied brain areas; high gamma activity was limited to canonical auditory cortex. Sedation led to a decrease in AEP magnitude. Upon LOC, there was a decrease in the superior temporal gyrus and adjacent auditory-related cortex and a further decrease in AEP magnitude in core auditory cortex, changes in the temporal structure and increased trial-to-trial variability of responses. The findings identify putative biomarkers of LOC and serve as a foundation for future investigations of altered sensory processing.
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Affiliation(s)
- Kirill V Nourski
- Address correspondence to Kirill V. Nourski, MD, PhD, Department of Neurosurgery, The University of Iowa, 200 Hawkins Dr. 1815 JCP, Iowa City, IA 52242, USA.
| | - Mitchell Steinschneider
- Department of Neurology and Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ariane E Rhone
- Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA
| | - Bryan M Krause
- Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Rashmi N Mueller
- Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA,Department of Anesthesia, The University of Iowa, Iowa City, IA 52242, USA
| | - Hiroto Kawasaki
- Department of Neurosurgery, The University of Iowa, Iowa City, IA 52242, USA
| | - Matthew I Banks
- Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA,Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
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20
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Anterior insula regulates brain network transitions that gate conscious access. Cell Rep 2021; 35:109081. [PMID: 33951427 PMCID: PMC8157795 DOI: 10.1016/j.celrep.2021.109081] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 02/19/2021] [Accepted: 04/13/2021] [Indexed: 12/20/2022] Open
Abstract
Conscious access to sensory information is likely gated at an intermediate site between primary sensory and transmodal association cortices, but the structure responsible remains unknown. We perform functional neuroimaging to determine the neural correlates of conscious access using a volitional mental imagery task, a report paradigm not confounded by motor behavior. Titrating propofol to loss of behavioral responsiveness in healthy volunteers creates dysfunction of the anterior insular cortex (AIC) in association with an impairment of dynamic transitions of default-mode and dorsal attention networks. Candidate subcortical regions mediating sensory gating or arousal (thalamus, basal forebrain) fail to show this association. The gating role of the AIC is consistent with findings in awake participants, whose conscious access is predicted by pre-stimulus AIC activity near perceptual threshold. These data support the hypothesis that AIC, situated at an intermediate position of the cortical hierarchy, regulates brain network transitions that gate conscious access. In a human neuroimaging study, Huang et al. manipulate the level and content of consciousness using independent experimental protocols to demonstrate that the anterior insula, situated between unimodal and transmodal cortical areas along the brain’s functional hierarchy, serves as a gate for conscious access of sensory information.
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21
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Pujol J, Blanco-Hinojo L, Gallart L, Moltó L, Martínez-Vilavella G, Vilà E, Pacreu S, Adalid I, Deus J, Pérez-Sola V, Fernández-Candil J. Largest scale dissociation of brain activity at propofol-induced loss of consciousness. Sleep 2021; 44:5894260. [PMID: 32813022 DOI: 10.1093/sleep/zsaa152] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/06/2020] [Indexed: 11/14/2022] Open
Abstract
The brain is a functional unit made up of multilevel connected elements showing a pattern of synchronized activity that varies in different states. The wake-sleep cycle is a major variation of brain functional condition that is ultimately regulated by subcortical arousal- and sleep-promoting cell groups. We analyzed the evolution of functional MRI (fMRI) signal in the whole cortex and in a deep region including most sleep- and wake-regulating subcortical nuclei at loss of consciousness induced by the hypnotic agent propofol. Optimal data were obtained in 21 of the 30 healthy participants examined. A dynamic analysis of fMRI time courses on a time-scale of seconds was conducted to characterize consciousness transition, and functional connectivity maps were generated to detail the anatomy of structures showing different dynamics. Inside the magnet, loss of consciousness was marked by the participants ceasing to move their hands. We observed activity synchronization after loss of consciousness within both the cerebral cortex and subcortical structures. However, the evolution of fMRI signal was dissociated, showing a transient reduction of global cortico-subcortical coupling that was restored during the unconscious state. An exception to cortico-subcortical decoupling was a brain network related to self-awareness (i.e. the default mode network) that remained connected to subcortical brain structures. Propofol-induced unconsciousness is thus characterized by an initial, transitory dissociated synchronization at the largest scale of brain activity. Such cortico-subcortical decoupling and subsequent recoupling may allow the brain to detach from waking activity and reorganize into a functionally distinct state.
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Affiliation(s)
- Jesus Pujol
- MRI Research Unit, Department of Radiology, Hospital del Mar, Barcelona, Spain.,Centro Investigación Biomédica en Red de Salud Mental, CIBERSAM G21, Barcelona, Spain
| | - Laura Blanco-Hinojo
- MRI Research Unit, Department of Radiology, Hospital del Mar, Barcelona, Spain.,Centro Investigación Biomédica en Red de Salud Mental, CIBERSAM G21, Barcelona, Spain
| | - Lluís Gallart
- Department of Anesthesiology, Hospital del Mar-IMIM, Barcelona, Spain.,Department of Surgery, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luís Moltó
- Department of Anesthesiology, Hospital del Mar-IMIM, Barcelona, Spain
| | | | - Esther Vilà
- Department of Anesthesiology, Hospital del Mar-IMIM, Barcelona, Spain
| | - Susana Pacreu
- Department of Anesthesiology, Hospital del Mar-IMIM, Barcelona, Spain
| | - Irina Adalid
- Department of Anesthesiology, Hospital del Mar-IMIM, Barcelona, Spain
| | - Joan Deus
- MRI Research Unit, Department of Radiology, Hospital del Mar, Barcelona, Spain.,Department of Psychobiology and Methodology in Health Sciences, Autonomous University of Barcelona, Barcelona, Spain
| | - Víctor Pérez-Sola
- Centro Investigación Biomédica en Red de Salud Mental, CIBERSAM G21, Barcelona, Spain.,Institute of Neuropsychiatry and Addictions, Hospital del Mar-IMIM and Department of Psychiatry, Autonomous University of Barcelona, Barcelona, Spain
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22
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Rocchi F, Oya H, Balezeau F, Billig AJ, Kocsis Z, Jenison RL, Nourski KV, Kovach CK, Steinschneider M, Kikuchi Y, Rhone AE, Dlouhy BJ, Kawasaki H, Adolphs R, Greenlee JDW, Griffiths TD, Howard MA, Petkov CI. Common fronto-temporal effective connectivity in humans and monkeys. Neuron 2021; 109:852-868.e8. [PMID: 33482086 PMCID: PMC7927917 DOI: 10.1016/j.neuron.2020.12.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 10/02/2020] [Accepted: 12/30/2020] [Indexed: 01/24/2023]
Abstract
Human brain pathways supporting language and declarative memory are thought to have differentiated substantially during evolution. However, cross-species comparisons are missing on site-specific effective connectivity between regions important for cognition. We harnessed functional imaging to visualize the effects of direct electrical brain stimulation in macaque monkeys and human neurosurgery patients. We discovered comparable effective connectivity between caudal auditory cortex and both ventro-lateral prefrontal cortex (VLPFC, including area 44) and parahippocampal cortex in both species. Human-specific differences were clearest in the form of stronger hemispheric lateralization effects. In humans, electrical tractography revealed remarkably rapid evoked potentials in VLPFC following auditory cortex stimulation and speech sounds drove VLPFC, consistent with prior evidence in monkeys of direct auditory cortex projections to homologous vocalization-responsive regions. The results identify a common effective connectivity signature in human and nonhuman primates, which from auditory cortex appears equally direct to VLPFC and indirect to the hippocampus. VIDEO ABSTRACT.
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Affiliation(s)
- Francesca Rocchi
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK.
| | - Hiroyuki Oya
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, The University of Iowa, Iowa City, IA, USA.
| | - Fabien Balezeau
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | | | - Zsuzsanna Kocsis
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK; Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA
| | - Rick L Jenison
- Department of Neuroscience, University of Wisconsin - Madison, Madison, WI, USA
| | - Kirill V Nourski
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, The University of Iowa, Iowa City, IA, USA
| | | | - Mitchell Steinschneider
- Departments of Neurology and Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Yukiko Kikuchi
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - Ariane E Rhone
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA
| | - Brian J Dlouhy
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, The University of Iowa, Iowa City, IA, USA
| | - Hiroto Kawasaki
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA
| | - Ralph Adolphs
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Jeremy D W Greenlee
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, The University of Iowa, Iowa City, IA, USA
| | - Timothy D Griffiths
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK; Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA; Wellcome Centre for Human Neuroimaging, University College London, London, UK
| | - Matthew A Howard
- Department of Neurosurgery, The University of Iowa, Iowa City, IA, USA; Iowa Neuroscience Institute, The University of Iowa, Iowa City, IA, USA; Pappajohn Biomedical Institute, The University of Iowa, Iowa City, IA, USA
| | - Christopher I Petkov
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK.
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23
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Edlow BL, Naccache L. Unmasking Covert Language Processing in the Intensive Care Unit with Electroencephalography. Ann Neurol 2021; 89:643-645. [PMID: 33491250 PMCID: PMC8048541 DOI: 10.1002/ana.26030] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 01/16/2023]
Affiliation(s)
- Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA
| | - Lionel Naccache
- PICNIC Lab Team, INSERM, U 1127, CNRS UMR 7225, Faculté de Médecine de Sorbonne Université, UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Hôpital Pitié-Salpêtrière, Paris, France.,APHP, Departments of Neurology and of Clinical Neurophysiology, Hôpital de la Salpêtriere, Paris, France
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24
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Sokoliuk R, Degano G, Banellis L, Melloni L, Hayton T, Sturman S, Veenith T, Yakoub KM, Belli A, Noppeney U, Cruse D. Covert Speech Comprehension Predicts Recovery From Acute Unresponsive States. Ann Neurol 2021; 89:646-656. [PMID: 33368496 DOI: 10.1002/ana.25995] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Patients with traumatic brain injury who fail to obey commands after sedation-washout pose one of the most significant challenges for neurological prognostication. Reducing prognostic uncertainty will lead to more appropriate care decisions and ensure provision of limited rehabilitation resources to those most likely to benefit. Bedside markers of covert residual cognition, including speech comprehension, may reduce this uncertainty. METHODS We recruited 28 patients with acute traumatic brain injury who were 2 to 7 days sedation-free and failed to obey commands. Patients heard streams of isochronous monosyllabic words that built meaningful phrases and sentences while their brain activity via electroencephalography (EEG) was recorded. In healthy individuals, EEG activity only synchronizes with the rhythm of phrases and sentences when listeners consciously comprehend the speech. This approach therefore provides a measure of residual speech comprehension in unresponsive patients. RESULTS Seventeen and 16 patients were available for assessment with the Glasgow Outcome Scale Extended (GOSE) at 3 months and 6 months, respectively. Outcome significantly correlated with the strength of patients' acute cortical tracking of phrases and sentences (r > 0.6, p < 0.007), quantified by inter-trial phase coherence. Linear regressions revealed that the strength of this comprehension response (beta = 0.603, p = 0.006) significantly improved the accuracy of prognoses relative to clinical characteristics alone (eg, Glasgow Coma Scale [GCS], computed tomography [CT] grade). INTERPRETATION A simple, passive, auditory EEG protocol improves prognostic accuracy in a critical period of clinical decision making. Unlike other approaches to probing covert cognition for prognostication, this approach is entirely passive and therefore less susceptible to cognitive deficits, increasing the number of patients who may benefit. ANN NEUROL 2021;89:646-656.
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Affiliation(s)
- Rodika Sokoliuk
- School of Psychology, University of Birmingham, Birmingham, UK.,Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Giulio Degano
- School of Psychology, University of Birmingham, Birmingham, UK.,Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Leah Banellis
- School of Psychology, University of Birmingham, Birmingham, UK.,Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Lucia Melloni
- Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, Frankfurt, Germany.,Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Tom Hayton
- Surgical Reconstruction and Microbiology Research Centre, National Institute for Health Research, Birmingham, UK
| | - Steve Sturman
- Surgical Reconstruction and Microbiology Research Centre, National Institute for Health Research, Birmingham, UK
| | - Tonny Veenith
- Surgical Reconstruction and Microbiology Research Centre, National Institute for Health Research, Birmingham, UK.,Birmingham Acute Care Research Group, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
| | - Kamal M Yakoub
- Surgical Reconstruction and Microbiology Research Centre, National Institute for Health Research, Birmingham, UK
| | - Antonio Belli
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK.,Surgical Reconstruction and Microbiology Research Centre, National Institute for Health Research, Birmingham, UK
| | - Uta Noppeney
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Damian Cruse
- School of Psychology, University of Birmingham, Birmingham, UK.,Centre for Human Brain Health, University of Birmingham, Birmingham, UK
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25
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Wang J, Sun P, Liang P. Neuropsychopharmacological effects of midazolam on the human brain. Brain Inform 2020; 7:15. [PMID: 33170396 PMCID: PMC7655878 DOI: 10.1186/s40708-020-00116-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 10/26/2020] [Indexed: 12/17/2022] Open
Abstract
As a commonly used anesthetic agent, midazolam has the properties of water-soluble, rapid onset, and short duration of action. With the rapid development in the field of neuroimaging, numerous studies have investigated how midazolam acts on the human brain to induce the alteration of consciousness. However, the neural bases of midazolam-induced sedation or anesthesia remain beginning to be understood in detail. In this review, we summarize findings from neuroimaging studies that have used midazolam to study altered consciousness at different levels and content. We also compare the results to those of neuroimaging studies using diverse anesthetic agents and describe the common neural correlates of anesthetic-induced alteration of consciousness.
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Affiliation(s)
- Junkai Wang
- School of Psychology, Capital Normal University, Haidian District, Beijing, 100048, China.,Beijing Key Laboratory of Learning and Cognition, Beijing, China.,Department of Psychology, Tsinghua University, Haidian District, Beijing, 100084, China
| | - Pei Sun
- Department of Psychology, Tsinghua University, Haidian District, Beijing, 100084, China.
| | - Peipeng Liang
- School of Psychology, Capital Normal University, Haidian District, Beijing, 100048, China. .,Beijing Key Laboratory of Learning and Cognition, Beijing, China.
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26
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Karnatovskaia LV, Johnson MM, Varga K, Highfield JA, Wolfrom BD, Philbrick KL, Ely EW, Jackson JC, Gajic O, Ahmad SR, Niven AS. Stress and Fear: Clinical Implications for Providers and Patients (in the Time of COVID-19 and Beyond). Mayo Clin Proc 2020; 95:2487-2498. [PMID: 33153636 PMCID: PMC7606075 DOI: 10.1016/j.mayocp.2020.08.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/13/2020] [Accepted: 08/25/2020] [Indexed: 12/27/2022]
Abstract
In light of the coronavirus disease 2019 pandemic, we explore the role of stress, fear, and the impact of positive and negative emotions on health and disease. We then introduce strategies to help mitigate stress within the health care team, and provide a rationale for their efficacy. Additionally, we identify strategies to optimize patient care and explain their heightened importance in today's environment.
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Affiliation(s)
| | | | - Katalin Varga
- Affective Psychology Department, Eötvös Loránd University, Budapest, Hungary
| | - Julie A Highfield
- Department of Clinical Psychology in Critical Care, University Hospital Wales, Cardiff, UK
| | - Brent D Wolfrom
- Department of Family Medicine, Queen's University, Kingston, Canada
| | | | - E Wesley Ely
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN; Critical Illness, Brain Dysfunction, and Survivorship (CIBS) Center, Vanderbilt University Medical Center, Nashville, TN; Geriatric Research, Education and Clinical Center (GRECC), Tennessee Valley Veterans Affairs Healthcare System, Nashville, TN
| | - James C Jackson
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
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27
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Fedorenko E, Blank IA, Siegelman M, Mineroff Z. Lack of selectivity for syntax relative to word meanings throughout the language network. Cognition 2020; 203:104348. [PMID: 32569894 DOI: 10.1101/477851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 05/14/2020] [Accepted: 05/31/2020] [Indexed: 05/25/2023]
Abstract
To understand what you are reading now, your mind retrieves the meanings of words and constructions from a linguistic knowledge store (lexico-semantic processing) and identifies the relationships among them to construct a complex meaning (syntactic or combinatorial processing). Do these two sets of processes rely on distinct, specialized mechanisms or, rather, share a common pool of resources? Linguistic theorizing, empirical evidence from language acquisition and processing, and computational modeling have jointly painted a picture whereby lexico-semantic and syntactic processing are deeply inter-connected and perhaps not separable. In contrast, many current proposals of the neural architecture of language continue to endorse a view whereby certain brain regions selectively support syntactic/combinatorial processing, although the locus of such "syntactic hub", and its nature, vary across proposals. Here, we searched for selectivity for syntactic over lexico-semantic processing using a powerful individual-subjects fMRI approach across three sentence comprehension paradigms that have been used in prior work to argue for such selectivity: responses to lexico-semantic vs. morpho-syntactic violations (Experiment 1); recovery from neural suppression across pairs of sentences differing in only lexical items vs. only syntactic structure (Experiment 2); and same/different meaning judgments on such sentence pairs (Experiment 3). Across experiments, both lexico-semantic and syntactic conditions elicited robust responses throughout the left fronto-temporal language network. Critically, however, no regions were more strongly engaged by syntactic than lexico-semantic processing, although some regions showed the opposite pattern. Thus, contra many current proposals of the neural architecture of language, syntactic/combinatorial processing is not separable from lexico-semantic processing at the level of brain regions-or even voxel subsets-within the language network, in line with strong integration between these two processes that has been consistently observed in behavioral and computational language research. The results further suggest that the language network may be generally more strongly concerned with meaning than syntactic form, in line with the primary function of language-to share meanings across minds.
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Affiliation(s)
- Evelina Fedorenko
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.
| | - Idan Asher Blank
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Department of Psychology, UCLA, Los Angeles, CA 90095, USA
| | - Matthew Siegelman
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Department of Psychology, Columbia University, New York, NY 10027, USA
| | - Zachary Mineroff
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Eberly Center for Teaching Excellence & Educational Innovation, CMU, Pittsburgh, PA 15213, USA
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28
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Klooster N, McQuire M, Grossman M, McMillan C, Chatterjee A, Cardillo E. The Neural Basis of Metaphor Comprehension: Evidence from Left Hemisphere Degeneration. NEUROBIOLOGY OF LANGUAGE (CAMBRIDGE, MASS.) 2020; 1:474-491. [PMID: 37215584 PMCID: PMC10158586 DOI: 10.1162/nol_a_00022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/14/2020] [Indexed: 05/24/2023]
Abstract
Despite the ubiquity of metaphor in cognition and communication, it is absent from standard clinical assessments of language, and the neural systems that support metaphor processing are debated. Previous research shows that patients with focal brain lesions can display selective impairments in processing metaphor, suggesting that figurative language abilities may be disproportionately vulnerable to brain injury. We hypothesized that metaphor processing is especially vulnerable to neurodegenerative disease, and that the left hemisphere is critical for normal metaphor processing. To evaluate these hypotheses, we tested metaphor comprehension in patients with left-hemisphere neurodegeneration, and in demographically matched healthy comparison participants. Stimuli consisted of moderately familiar metaphors and closely matched literal sentences sharing the same source term (e.g., The interview was a painful crawl / The infant's motion was a crawl). Written sentences were presented, followed by four modifier-noun answer choices (one target and three foils). Healthy controls, though reliably better at literal than metaphor trials, comprehended both sentence conditions well. By contrast, participants with left-hemisphere neurodegeneration performed disproportionately poorly on metaphor comprehension. Anatomical analyses show relationships between metaphor accuracy and patient atrophy in the left middle and superior temporal gyri, and the left inferior frontal gyrus, areas that have been implicated in supporting metaphor comprehension in previous imaging research. The behavioral results also suggest deficits of metaphor comprehension may be a sensitive measure of cognitive dysfunction in some forms of neurodegenerative disease.
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Affiliation(s)
- Nathaniel Klooster
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Frontotemporal Degeneration Center, University of Pennsylvania, Philadelphia, PA, USA
| | - Marguerite McQuire
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Murray Grossman
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Frontotemporal Degeneration Center, University of Pennsylvania, Philadelphia, PA, USA
| | - Corey McMillan
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Frontotemporal Degeneration Center, University of Pennsylvania, Philadelphia, PA, USA
| | - Anjan Chatterjee
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Moss Rehabilitation Research Institute, Elkins Park, PA, USA
- Penn Center for Neuroaesthetics, University of Pennsylvania, Philadelphia, PA, USA
| | - Eileen Cardillo
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Center for Neuroaesthetics, University of Pennsylvania, Philadelphia, PA, USA
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29
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Fedorenko E, Blank IA, Siegelman M, Mineroff Z. Lack of selectivity for syntax relative to word meanings throughout the language network. Cognition 2020; 203:104348. [PMID: 32569894 PMCID: PMC7483589 DOI: 10.1016/j.cognition.2020.104348] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 05/14/2020] [Accepted: 05/31/2020] [Indexed: 12/31/2022]
Abstract
To understand what you are reading now, your mind retrieves the meanings of words and constructions from a linguistic knowledge store (lexico-semantic processing) and identifies the relationships among them to construct a complex meaning (syntactic or combinatorial processing). Do these two sets of processes rely on distinct, specialized mechanisms or, rather, share a common pool of resources? Linguistic theorizing, empirical evidence from language acquisition and processing, and computational modeling have jointly painted a picture whereby lexico-semantic and syntactic processing are deeply inter-connected and perhaps not separable. In contrast, many current proposals of the neural architecture of language continue to endorse a view whereby certain brain regions selectively support syntactic/combinatorial processing, although the locus of such "syntactic hub", and its nature, vary across proposals. Here, we searched for selectivity for syntactic over lexico-semantic processing using a powerful individual-subjects fMRI approach across three sentence comprehension paradigms that have been used in prior work to argue for such selectivity: responses to lexico-semantic vs. morpho-syntactic violations (Experiment 1); recovery from neural suppression across pairs of sentences differing in only lexical items vs. only syntactic structure (Experiment 2); and same/different meaning judgments on such sentence pairs (Experiment 3). Across experiments, both lexico-semantic and syntactic conditions elicited robust responses throughout the left fronto-temporal language network. Critically, however, no regions were more strongly engaged by syntactic than lexico-semantic processing, although some regions showed the opposite pattern. Thus, contra many current proposals of the neural architecture of language, syntactic/combinatorial processing is not separable from lexico-semantic processing at the level of brain regions-or even voxel subsets-within the language network, in line with strong integration between these two processes that has been consistently observed in behavioral and computational language research. The results further suggest that the language network may be generally more strongly concerned with meaning than syntactic form, in line with the primary function of language-to share meanings across minds.
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Affiliation(s)
- Evelina Fedorenko
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; McGovern Institute for Brain Research, MIT, Cambridge, MA 02139, USA.
| | - Idan Asher Blank
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Department of Psychology, UCLA, Los Angeles, CA 90095, USA
| | - Matthew Siegelman
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Department of Psychology, Columbia University, New York, NY 10027, USA
| | - Zachary Mineroff
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 02139, USA; Eberly Center for Teaching Excellence & Educational Innovation, CMU, Pittsburgh, PA 15213, USA
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30
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Kandeepan S, Rudas J, Gomez F, Stojanoski B, Valluri S, Owen AM, Naci L, Nichols ES, Soddu A. Modeling an auditory stimulated brain under altered states of consciousness using the generalized Ising model. Neuroimage 2020; 223:117367. [PMID: 32931944 DOI: 10.1016/j.neuroimage.2020.117367] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 08/08/2020] [Accepted: 09/08/2020] [Indexed: 10/23/2022] Open
Abstract
Propofol is a short-acting medication that results in decreased levels of consciousness and is used for general anesthesia. Although it is the most commonly used anesthetic in the world, much remains unknown about the mechanisms by which it induces a loss of consciousness. Characterizing anesthesia-induced alterations to brain network activity might provide a powerful framework for understanding the neural mechanisms of unconsciousness. The aim of this work was to model brain activity in healthy brains during various stages of consciousness, as induced by propofol, in the auditory paradigm. We used the generalized Ising model (GIM) to fit the empirical fMRI data of healthy subjects while they listened to an audio clip from a movie. The external stimulus (audio clip) is believed to be at least partially driving a synchronization process of the brain activity and provides a similar conscious experience in different subjects. In order to observe the common synchronization among the subjects, a novel technique called the inter subject correlation (ISC) was implemented. We showed that the GIM-modified to incorporate the naturalistic external field-was able to fit the empirical task fMRI data in the awake state, in mild sedation, in deep sedation, and in recovery, at a temperature T* which is well above the critical temperature. To our knowledge this is the first study that captures human brain activity in response to real-life external stimuli at different levels of conscious awareness using mathematical modeling. This study might be helpful in the future to assess the level of consciousness of patients with disorders of consciousness and help in regaining their consciousness.
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Affiliation(s)
- Sivayini Kandeepan
- Department of Physics and Astronomy and the Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada; Department of Physics, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka.
| | - Jorge Rudas
- Department of Mathematics, Universidad Nacional de Colombia, Cra 45, Bogotá, Colombia
| | - Francisco Gomez
- Department of Mathematics, Universidad Nacional de Colombia, Cra 45, Bogotá, Colombia
| | - Bobby Stojanoski
- Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
| | - Sreeram Valluri
- Department of Physics and Astronomy and the Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada
| | - Adrian Mark Owen
- Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
| | - Lorina Naci
- Trinity College Institute of Neuroscience, Trinity College Dublin, College Green, Dublin 2, Ireland
| | - Emily Sophia Nichols
- Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A 3K7, Canada
| | - Andrea Soddu
- Department of Physics and Astronomy and the Brain and Mind Institute, University of Western Ontario, 1151 Richmond St, London, ON, N6A 3K7, Canada
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31
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Krom AJ, Marmelshtein A, Gelbard-Sagiv H, Tankus A, Hayat H, Hayat D, Matot I, Strauss I, Fahoum F, Soehle M, Boström J, Mormann F, Fried I, Nir Y. Anesthesia-induced loss of consciousness disrupts auditory responses beyond primary cortex. Proc Natl Acad Sci U S A 2020; 117:11770-11780. [PMID: 32398367 PMCID: PMC7261054 DOI: 10.1073/pnas.1917251117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Despite its ubiquitous use in medicine, and extensive knowledge of its molecular and cellular effects, how anesthesia induces loss of consciousness (LOC) and affects sensory processing remains poorly understood. Specifically, it is unclear whether anesthesia primarily disrupts thalamocortical relay or intercortical signaling. Here we recorded intracranial electroencephalogram (iEEG), local field potentials (LFPs), and single-unit activity in patients during wakefulness and light anesthesia. Propofol infusion was gradually increased while auditory stimuli were presented and patients responded to a target stimulus until they became unresponsive. We found widespread iEEG responses in association cortices during wakefulness, which were attenuated and restricted to auditory regions upon LOC. Neuronal spiking and LFP responses in primary auditory cortex (PAC) persisted after LOC, while responses in higher-order auditory regions were variable, with neuronal spiking largely attenuated. Gamma power induced by word stimuli increased after LOC while its frequency profile slowed, thus differing from local spiking activity. In summary, anesthesia-induced LOC disrupts auditory processing in association cortices while relatively sparing responses in PAC, opening new avenues for future research into mechanisms of LOC and the design of anesthetic monitoring devices.
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Affiliation(s)
- Aaron J Krom
- Department of Physiology & Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Anesthesiology and Critical Care Medicine, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
- Hadassah School of Medicine, Hebrew University, Jerusalem 91120, Israel
| | - Amit Marmelshtein
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Hagar Gelbard-Sagiv
- Department of Physiology & Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ariel Tankus
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
- Functional Neurosurgery Unit, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel
- Department of Neurology & Neurosurgery, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Hanna Hayat
- Department of Physiology & Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Daniel Hayat
- Department of Anesthesia, Intensive Care and Pain, Tel Aviv Medical Center, Sackler Medical School, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Idit Matot
- Department of Anesthesia, Intensive Care and Pain, Tel Aviv Medical Center, Sackler Medical School, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ido Strauss
- Functional Neurosurgery Unit, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel
- Department of Neurology & Neurosurgery, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Firas Fahoum
- Department of Neurology & Neurosurgery, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- EEG and Epilepsy Unit, Department of Neurology, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel
| | - Martin Soehle
- Department of Anesthesiology and Intensive Care Medicine, University of Bonn Medical Center, 53127 Bonn, Germany
| | - Jan Boström
- Department of Neurosurgery, University of Bonn Medical Center, 53127 Bonn, Germany
| | - Florian Mormann
- Department of Epileptology, University of Bonn Medical Center, 53127 Bonn, Germany
| | - Itzhak Fried
- Functional Neurosurgery Unit, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel;
- Department of Neurology & Neurosurgery, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Neurosurgery, University of California, Los Angeles, CA 90095
| | - Yuval Nir
- Department of Physiology & Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel;
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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32
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Gui P, Jiang Y, Zang D, Qi Z, Tan J, Tanigawa H, Jiang J, Wen Y, Xu L, Zhao J, Mao Y, Poo MM, Ding N, Dehaene S, Wu X, Wang L. Assessing the depth of language processing in patients with disorders of consciousness. Nat Neurosci 2020; 23:761-770. [DOI: 10.1038/s41593-020-0639-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 04/08/2020] [Indexed: 12/18/2022]
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33
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MacGregor LJ, Rodd JM, Gilbert RA, Hauk O, Sohoglu E, Davis MH. The Neural Time Course of Semantic Ambiguity Resolution in Speech Comprehension. J Cogn Neurosci 2020; 32:403-425. [PMID: 31682564 PMCID: PMC7116495 DOI: 10.1162/jocn_a_01493] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Semantically ambiguous words challenge speech comprehension, particularly when listeners must select a less frequent (subordinate) meaning at disambiguation. Using combined magnetoencephalography (MEG) and EEG, we measured neural responses associated with distinct cognitive operations during semantic ambiguity resolution in spoken sentences: (i) initial activation and selection of meanings in response to an ambiguous word and (ii) sentence reinterpretation in response to subsequent disambiguation to a subordinate meaning. Ambiguous words elicited an increased neural response approximately 400-800 msec after their acoustic offset compared with unambiguous control words in left frontotemporal MEG sensors, corresponding to sources in bilateral frontotemporal brain regions. This response may reflect increased demands on processes by which multiple alternative meanings are activated and maintained until later selection. Disambiguating words heard after an ambiguous word were associated with marginally increased neural activity over bilateral temporal MEG sensors and a central cluster of EEG electrodes, which localized to similar bilateral frontal and left temporal regions. This later neural response may reflect effortful semantic integration or elicitation of prediction errors that guide reinterpretation of previously selected word meanings. Across participants, the amplitude of the ambiguity response showed a marginal positive correlation with comprehension scores, suggesting that sentence comprehension benefits from additional processing around the time of an ambiguous word. Better comprehenders may have increased availability of subordinate meanings, perhaps due to higher quality lexical representations and reflected in a positive correlation between vocabulary size and comprehension success.
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Affiliation(s)
| | - Jennifer M. Rodd
- Department of Experimental Psychology, University College London
| | | | - Olaf Hauk
- MRC Cognition and Brain Sciences Unit, University of Cambridge
| | - Ediz Sohoglu
- MRC Cognition and Brain Sciences Unit, University of Cambridge
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Rodd JM. Settling Into Semantic Space: An Ambiguity-Focused Account of Word-Meaning Access. PERSPECTIVES ON PSYCHOLOGICAL SCIENCE 2020; 15:411-427. [PMID: 31961780 DOI: 10.1177/1745691619885860] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Most words are ambiguous: Individual word forms (e.g., run) can map onto multiple different interpretations depending on their sentence context (e.g., the athlete/politician/river runs). Models of word-meaning access must therefore explain how listeners and readers can rapidly settle on a single, contextually appropriate meaning for each word that they encounter. I present a new account of word-meaning access that places semantic disambiguation at its core and integrates evidence from a wide variety of experimental approaches to explain this key aspect of language comprehension. The model has three key characteristics. (a) Lexical-semantic knowledge is viewed as a high-dimensional space; familiar word meanings correspond to stable states within this lexical-semantic space. (b) Multiple linguistic and paralinguistic cues can influence the settling process by which the system resolves on one of these familiar meanings. (c) Learning mechanisms play a vital role in facilitating rapid word-meaning access by shaping and maintaining high-quality lexical-semantic knowledge throughout the life span. In contrast to earlier models of word-meaning access, I highlight individual differences in lexical-semantic knowledge: Each person's lexicon is uniquely structured by specific, idiosyncratic linguistic experiences.
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Affiliation(s)
- Jennifer M Rodd
- Department of Experimental Psychology, University College London
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35
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Edlow BL, Fins JJ. Assessment of Covert Consciousness in the Intensive Care Unit: Clinical and Ethical Considerations. J Head Trauma Rehabil 2019; 33:424-434. [PMID: 30395042 PMCID: PMC6317885 DOI: 10.1097/htr.0000000000000448] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To propose a practical ethical framework for how task-based functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) may be used in the intensive care unit (ICU) to identify covert consciousness in patients with acute severe traumatic brain injury (TBI). METHODS We present 2 clinical scenarios in which investigational task-based fMRI and EEG were performed in critically ill patients with acute severe TBI who appeared unconscious on the bedside behavioral assessment. From these cases, we consider the clinical and ethical challenges that emerge and suggest how to reconcile them. We also provide recommendations regarding communication with families about ICU patients with covert consciousness. RESULTS Covert consciousness was detected acutely in a patient who died in the ICU due to withdrawal of life-sustaining therapy, whereas covert consciousness was not detected in a patient who subsequently recovered consciousness, communication, and functional independence. These cases raise ethical challenges about how assessment of covert consciousness in the ICU might inform treatment decisions, prognostication, and perceptions about the benefits and burdens of ongoing care. CONCLUSIONS Given that covert consciousness can be detected acutely in the ICU, we recommend that clinicians reconsider evaluative norms for ICU patients. As our clinical appreciation of covert consciousness evolves and its ethical import unfolds, we urge prognostic humility and transparency when clinicians communicate with families in the ICU about goals of care.
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Affiliation(s)
- Brian L Edlow
- Department of Neurology, Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, and Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown (Dr Edlow); and Division of Medical Ethics and Consortium for the Advanced Study of Brain Injury, Weill Cornell Medical College, New York, and The Rockefeller University, New York, and the Solomon Center for Health Law and Policy, Yale Law School, New Haven, Connecticut (Dr Fins)
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36
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Liu X, Lauer KK, Ward BD, Roberts CJ, Liu S, Gollapudy S, Rohloff R, Gross W, Xu Z, Chen S, Wang L, Yang Z, Li SJ, Binder JR, Hudetz AG. Regional entropy of functional imaging signals varies differently in sensory and cognitive systems during propofol-modulated loss and return of behavioral responsiveness. Brain Imaging Behav 2019; 13:514-525. [PMID: 29737490 DOI: 10.1007/s11682-018-9886-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The level and richness of consciousness depend on information integration in the brain. Altered interregional functional interactions may indicate disrupted information integration during anesthetic-induced unconsciousness. How anesthetics modulate the amount of information in various brain regions has received less attention. Here, we propose a novel approach to quantify regional information content in the brain by the entropy of the principal components of regional blood oxygen-dependent imaging signals during graded propofol sedation. Fifteen healthy individuals underwent resting-state scans in wakeful baseline, light sedation (conscious), deep sedation (unconscious), and recovery (conscious). Light sedation characterized by lethargic behavioral responses was associated with global reduction of entropy in the brain. Deep sedation with completely suppressed overt responsiveness was associated with further reductions of entropy in sensory (primary and higher sensory plus orbital prefrontal cortices) but not high-order cognitive (dorsal and medial prefrontal, cingulate, parietotemporal cortices and hippocampal areas) systems. Upon recovery of responsiveness, entropy was restored in the sensory but not in high-order cognitive systems. These findings provide novel evidence for a reduction of information content of the brain as a potential systems-level mechanism of reduced consciousness during propofol anesthesia. The differential changes of entropy in the sensory and high-order cognitive systems associated with losing and regaining overt responsiveness are consistent with the notion of "disconnected consciousness", in which a complete sensory-motor disconnection from the environment occurs with preserved internal mentation.
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Affiliation(s)
- Xiaolin Liu
- Department of Radiology, Center for Imaging Research, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
| | - Kathryn K Lauer
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - B Douglas Ward
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | | | - Suyan Liu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Suneeta Gollapudy
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert Rohloff
- Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - William Gross
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Zhan Xu
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Shanshan Chen
- Cognitive and Mental Health Research Center, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Lubin Wang
- Cognitive and Mental Health Research Center, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Zheng Yang
- Cognitive and Mental Health Research Center, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Shi-Jiang Li
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jeffrey R Binder
- Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Anthony G Hudetz
- Department of Anesthesiology and Center for Consciousness Science, University of Michigan, 1301 East Catherine Street, Ann Arbor, MI, 48109, USA.
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37
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No language unification without neural feedback: How awareness affects sentence processing. Neuroimage 2019; 202:116063. [PMID: 31376519 DOI: 10.1016/j.neuroimage.2019.116063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/22/2019] [Accepted: 07/30/2019] [Indexed: 01/08/2023] Open
Abstract
How does the human brain combine a finite number of words to form an infinite variety of sentences? According to the Memory, Unification and Control (MUC) model, sentence processing requires long-range feedback from the left inferior frontal cortex (LIFC) to left posterior temporal cortex (LPTC). Single word processing however may only require feedforward propagation of semantic information from sensory regions to LPTC. Here we tested the claim that long-range feedback is required for sentence processing by reducing visual awareness of words using a masking technique. Masking disrupts feedback processing while leaving feedforward processing relatively intact. Previous studies have shown that masked single words still elicit an N400 ERP effect, a neural signature of semantic incongruency. However, whether multiple words can be combined to form a sentence under reduced levels of awareness is controversial. To investigate this issue, we performed two experiments in which we measured electroencephalography (EEG) while 40 subjects performed a masked priming task. Words were presented either successively or simultaneously, thereby forming a short sentence that could be congruent or incongruent with a target picture. This sentence condition was compared with a typical single word condition. In the masked condition we only found an N400 effect for single words, whereas in the unmasked condition we observed an N400 effect for both unmasked sentences and single words. Our findings suggest that long-range feedback processing is required for sentence processing, but not for single word processing.
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38
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Walenski M, Europa E, Caplan D, Thompson CK. Neural networks for sentence comprehension and production: An ALE-based meta-analysis of neuroimaging studies. Hum Brain Mapp 2019; 40:2275-2304. [PMID: 30689268 DOI: 10.1002/hbm.24523] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 12/14/2018] [Accepted: 12/26/2018] [Indexed: 12/24/2022] Open
Abstract
Comprehending and producing sentences is a complex endeavor requiring the coordinated activity of multiple brain regions. We examined three issues related to the brain networks underlying sentence comprehension and production in healthy individuals: First, which regions are recruited for sentence comprehension and sentence production? Second, are there differences for auditory sentence comprehension vs. visual sentence comprehension? Third, which regions are specifically recruited for the comprehension of syntactically complex sentences? Results from activation likelihood estimation (ALE) analyses (from 45 studies) implicated a sentence comprehension network occupying bilateral frontal and temporal lobe regions. Regions implicated in production (from 15 studies) overlapped with the set of regions associated with sentence comprehension in the left hemisphere, but did not include inferior frontal cortex, and did not extend to the right hemisphere. Modality differences between auditory and visual sentence comprehension were found principally in the temporal lobes. Results from the analysis of complex syntax (from 37 studies) showed engagement of left inferior frontal and posterior temporal regions, as well as the right insula. The involvement of the right hemisphere in the comprehension of these structures has potentially important implications for language treatment and recovery in individuals with agrammatic aphasia following left hemisphere brain damage.
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Affiliation(s)
- Matthew Walenski
- Center for the Neurobiology of Language Recovery, Northwestern University, Evanston, Illinois.,Department of Communication Sciences and Disorders, School of Communication, Northwestern University, Evanston, Illinois
| | - Eduardo Europa
- Department of Neurology, University of California, San Francisco
| | - David Caplan
- Department of Neurology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts
| | - Cynthia K Thompson
- Center for the Neurobiology of Language Recovery, Northwestern University, Evanston, Illinois.,Department of Communication Sciences and Disorders, School of Communication, Northwestern University, Evanston, Illinois.,Department of Neurology, Feinberg School of Medicine, Northwestern University, Evanston, Illinois
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39
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Brodbeck C, Hong LE, Simon JZ. Rapid Transformation from Auditory to Linguistic Representations of Continuous Speech. Curr Biol 2018; 28:3976-3983.e5. [PMID: 30503620 DOI: 10.1016/j.cub.2018.10.042] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/06/2018] [Accepted: 10/16/2018] [Indexed: 01/06/2023]
Abstract
During speech perception, a central task of the auditory cortex is to analyze complex acoustic patterns to allow detection of the words that encode a linguistic message [1]. It is generally thought that this process includes at least one intermediate, phonetic, level of representations [2-6], localized bilaterally in the superior temporal lobe [7-9]. Phonetic representations reflect a transition from acoustic to linguistic information, classifying acoustic patterns into linguistically meaningful units, which can serve as input to mechanisms that access abstract word representations [10, 11]. While recent research has identified neural signals arising from successful recognition of individual words in continuous speech [12-15], no explicit neurophysiological signal has been found demonstrating the transition from acoustic and/or phonetic to symbolic, lexical representations. Here, we report a response reflecting the incremental integration of phonetic information for word identification, dominantly localized to the left temporal lobe. The short response latency, approximately 114 ms relative to phoneme onset, suggests that phonetic information is used for lexical processing as soon as it becomes available. Responses also tracked word boundaries, confirming previous reports of immediate lexical segmentation [16, 17]. These new results were further investigated using a cocktail-party paradigm [18, 19] in which participants listened to a mix of two talkers, attending to one and ignoring the other. Analysis indicates neural lexical processing of only the attended, but not the unattended, speech stream. Thus, while responses to acoustic features reflect attention through selective amplification of attended speech, responses consistent with a lexical processing model reveal categorically selective processing.
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Affiliation(s)
- Christian Brodbeck
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA.
| | - L Elliot Hong
- Department of Psychiatry, Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jonathan Z Simon
- Institute for Systems Research, University of Maryland, College Park, MD 20742, USA; Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742, USA; Department of Biology, University of Maryland, College Park, MD 20742, USA.
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40
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Huang Z, Zhang J, Wu J, Liu X, Xu J, Zhang J, Qin P, Dai R, Yang Z, Mao Y, Hudetz AG, Northoff G. Disrupted neural variability during propofol-induced sedation and unconsciousness. Hum Brain Mapp 2018; 39:4533-4544. [PMID: 29974570 PMCID: PMC6223306 DOI: 10.1002/hbm.24304] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 06/04/2018] [Accepted: 06/24/2018] [Indexed: 12/16/2022] Open
Abstract
Variability quenching is a widespread neural phenomenon in which trial-to-trial variability (TTV) of neural activity is reduced by repeated presentations of a sensory stimulus. However, its neural mechanism and functional significance remain poorly understood. Recurrent network dynamics are suggested as a candidate mechanism of TTV, and they play a key role in consciousness. We thus asked whether the variability-quenching phenomenon is related to the level of consciousness. We hypothesized that TTV reduction would be compromised during reduced level of consciousness by propofol anesthetics. We recorded functional magnetic resonance imaging signals of resting-state and stimulus-induced activities in three conditions: wakefulness, sedation, and unconsciousness (i.e., deep anesthesia). We measured the average (trial-to-trial mean, TTM) and variability (TTV) of auditory stimulus-induced activity under the three conditions. We also examined another form of neural variability (temporal variability, TV), which quantifies the overall dynamic range of ongoing neural activity across time, during both the resting-state and the task. We found that (a) TTM deceased gradually from wakefulness through sedation to anesthesia, (b) stimulus-induced TTV reduction normally seen during wakefulness was abolished during both sedation and anesthesia, and (c) TV increased in the task state as compared to resting-state during both wakefulness and sedation, but not anesthesia. Together, our results reveal distinct effects of propofol on the two forms of neural variability (TTV and TV). They imply that the anesthetic disrupts recurrent network dynamics, thus prevents the stabilization of cortical activity states. These findings shed new light on the temporal dynamics of neuronal variability and its alteration during anesthetic-induced unconsciousness.
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Affiliation(s)
- Zirui Huang
- Department of Anesthesiology and Center for Consciousness ScienceUniversity of MichiganAnn ArborMichigan
| | - Jun Zhang
- Department of AnesthesiologyHuashan Hospital, Fudan UniversityShanghaiPeople's Republic of China
| | - Jinsong Wu
- Neurological Surgery DepartmentHuashan Hospital, Shanghai Medical College, Fudan UniversityShanghaiPeople's Republic of China
| | - Xiaoge Liu
- Department of AnesthesiologyHuashan Hospital, Fudan UniversityShanghaiPeople's Republic of China
| | - Jianghui Xu
- Department of AnesthesiologyHuashan Hospital, Fudan UniversityShanghaiPeople's Republic of China
| | - Jianfeng Zhang
- College of Biomedical Engineering and Instrument ScienceZhejiang UniversityHangzhouPeople's Republic of China
| | - Pengmin Qin
- School of PsychologySouth China Normal UniversityGuangzhouPeople's Republic of China
| | - Rui Dai
- State Key Laboratory of Brain and Cognitive ScienceInstitute of Biophysics, Chinese Academy of SciencesBeijingPeople's Republic of China
| | - Zhong Yang
- Department of RadiologyHuashan Hospital, Fudan UniversityShanghaiPeople's Republic of China
| | - Ying Mao
- Neurological Surgery DepartmentHuashan Hospital, Shanghai Medical College, Fudan UniversityShanghaiPeople's Republic of China
| | - Anthony G. Hudetz
- Department of Anesthesiology and Center for Consciousness ScienceUniversity of MichiganAnn ArborMichigan
| | - Georg Northoff
- Institute of Mental Health ResearchUniversity of OttawaOttawaOntarioCanada
- Center for Cognition and Brain DisordersHangzhou Normal UniversityHangzhouPeople's Republic of China
- Mental Health CentreZhejiang University School of MedicineHangzhouPeople's Republic of China
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41
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Do New Neuroimaging Findings Challenge the Ethical Basis of Advance Directives in Disorders of Consciousness? Camb Q Healthc Ethics 2018; 27:675-685. [PMID: 30198470 DOI: 10.1017/s0963180118000166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Some authors have questioned the moral authority of advance directives (ADs) in cases in which it is not clear if the author of the AD is identical to the person to whom it later applies. This article focuses on the question of whether the latest results of neuroimaging studies have moral significance with regard to the moral authority of ADs in patients with disorders of consciousness (DOCs). Some neuroimaging findings could provide novel insights into the question of whether patients with DOCs exhibit sufficient psychological continuity to be ascribed diachronic personal identity. If those studies were to indicate that psychological continuity is present, they could justify the moral authority of ADs in patients with DOCs. This holds at least if respect for self-determination is considered as the foundation for the moral authority of ADs. The non-identity thesis in DOCs could no longer be applied, in line with clinical and social practice.
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42
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Functional diversity of brain networks supports consciousness and verbal intelligence. Sci Rep 2018; 8:13259. [PMID: 30185912 PMCID: PMC6125486 DOI: 10.1038/s41598-018-31525-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 08/15/2018] [Indexed: 11/08/2022] Open
Abstract
How are the myriad stimuli arriving at our senses transformed into conscious thought? To address this question, in a series of studies, we asked whether a common mechanism underlies loss of information processing in unconscious states across different conditions, which could shed light on the brain mechanisms of conscious cognition. With a novel approach, we brought together for the first time, data from the same paradigm-a highly engaging auditory-only narrative-in three independent domains: anesthesia-induced unconsciousness, unconsciousness after brain injury, and individual differences in intellectual abilities during conscious cognition. During external stimulation in the unconscious state, the functional differentiation between the auditory and fronto-parietal systems decreased significantly relatively to the conscious state. Conversely, we found that stronger functional differentiation between these systems in response to external stimulation predicted higher intellectual abilities during conscious cognition, in particular higher verbal acuity scores in independent cognitive testing battery. These convergent findings suggest that the responsivity of sensory and higher-order brain systems to external stimulation, especially through the diversification of their functional responses is an essential feature of conscious cognition and verbal intelligence.
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43
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Huang Z, Vlisides PE, Tarnal VC, Janke EL, Keefe KM, Collins MM, McKinney AM, Picton P, Harris RE, Mashour GA, Hudetz AG. Brain imaging reveals covert consciousness during behavioral unresponsiveness induced by propofol. Sci Rep 2018; 8:13195. [PMID: 30181567 PMCID: PMC6123455 DOI: 10.1038/s41598-018-31436-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/17/2018] [Indexed: 12/11/2022] Open
Abstract
Detecting covert consciousness in behaviorally unresponsive patients by brain imaging is of great interest, but a reproducible model and evidence from independent sources is still lacking. Here we demonstrate the possibility of using general anesthetics in a within-subjects study design to test methods or statistical paradigms of assessing covert consciousness. Using noninvasive neuroimaging in healthy volunteers, we identified a healthy study participant who was able to exhibit the specific fMRI signatures of volitional mental imagery while behaviorally unresponsive due to sedation with propofol. Our findings reveal a novel model that may accelerate the development of new approaches to reproducibly detect covert consciousness, which is difficult to achieve in patients with heterogeneous and sometimes clinically unstable neuropathology.
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Affiliation(s)
- Zirui Huang
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA.
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA.
| | - Phillip E Vlisides
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Vijaykumar C Tarnal
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ellen L Janke
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Kelley M Keefe
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Margaret M Collins
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Amy M McKinney
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Paul Picton
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Richard E Harris
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - George A Mashour
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Anthony G Hudetz
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, USA.
- Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI, USA.
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA.
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Threlkeld ZD, Bodien YG, Rosenthal ES, Giacino JT, Nieto-Castanon A, Wu O, Whitfield-Gabrieli S, Edlow BL. Functional networks reemerge during recovery of consciousness after acute severe traumatic brain injury. Cortex 2018; 106:299-308. [PMID: 29871771 PMCID: PMC6120794 DOI: 10.1016/j.cortex.2018.05.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/12/2018] [Accepted: 05/03/2018] [Indexed: 01/26/2023]
Abstract
Integrity of the default mode network (DMN) is believed to be essential for human consciousness. However, the effects of acute severe traumatic brain injury (TBI) on DMN functional connectivity are poorly understood. Furthermore, the temporal dynamics of DMN reemergence during recovery of consciousness have not been studied longitudinally in patients with acute severe TBI. We performed resting-state functional magnetic resonance imaging (rs-fMRI) to measure DMN connectivity in 17 patients admitted to the intensive care unit (ICU) with acute severe TBI and in 16 healthy control subjects. Eight patients returned for follow-up rs-fMRI and behavioral assessment six months post-injury. At each time point, we analyzed DMN connectivity by measuring intra-network correlations (i.e. positive correlations between DMN nodes) and inter-network anticorrelations (i.e. negative correlations between the DMN and other resting-state networks). All patients were comatose upon arrival to the ICU and had a disorder of consciousness (DoC) at the time of acute rs-fMRI (9.2 ± 4.6 days post-injury): 2 coma, 4 unresponsive wakefulness syndrome, 7 minimally conscious state, and 4 post-traumatic confusional state. We found that, while DMN anticorrelations were absent in patients with acute DoC, patients who recovered from coma to a minimally conscious or confusional state while in the ICU showed partially preserved DMN correlations. Patients who remained in coma or unresponsive wakefulness syndrome in the ICU showed no DMN correlations. All eight patients assessed longitudinally recovered beyond the confusional state by 6 months post-injury and showed normal DMN correlations and anticorrelations, indistinguishable from those of healthy subjects. Collectively, these findings suggest that recovery of consciousness after acute severe TBI is associated with partial preservation of DMN correlations in the ICU, followed by long-term normalization of DMN correlations and anticorrelations. Both intra-network DMN correlations and inter-network DMN anticorrelations may be necessary for full recovery of consciousness after acute severe TBI.
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Affiliation(s)
- Zachary D Threlkeld
- Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Yelena G Bodien
- Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Charlestown, MA, USA.
| | - Eric S Rosenthal
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Joseph T Giacino
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Charlestown, MA, USA.
| | - Alfonso Nieto-Castanon
- Department of Speech, Language, and Hearing Sciences, Boston University, Boston, MA, USA.
| | - Ona Wu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA.
| | - Susan Whitfield-Gabrieli
- Martinos Imaging Center at McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA.
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45
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Spoken words are processed during dexmedetomidine-induced unresponsiveness. Br J Anaesth 2018; 121:270-280. [PMID: 29935582 DOI: 10.1016/j.bja.2018.04.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/13/2018] [Accepted: 04/30/2018] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Studying the effects of anaesthetic drugs on the processing of semantic stimuli could yield insights into how brain functions change in the transition from wakefulness to unresponsiveness. Here, we explored the N400 event-related potential during dexmedetomidine- and propofol-induced unresponsiveness. METHODS Forty-seven healthy subjects were randomised to receive either dexmedetomidine (n=23) or propofol (n=24) in this open-label parallel-group study. Loss of responsiveness was achieved by stepwise increments of pseudo-steady-state plasma concentrations, and presumed loss of consciousness was induced using 1.5 times the concentration required for loss of responsiveness. Pre-recorded spoken sentences ending either with an expected (congruous) or an unexpected (incongruous) word were presented during unresponsiveness. The resulting electroencephalogram data were analysed for the presence of the N400 component, and for the N400 effect defined as the difference between the N400 components elicited by congruous and incongruous stimuli, in the time window 300-600 ms post-stimulus. Recognition of the presented stimuli was tested after recovery of responsiveness. RESULTS The N400 effect was not observed during dexmedetomidine- or propofol-induced unresponsiveness. The N400 component, however, persisted during dexmedetomidine administration. The N400 component elicited by congruous stimuli during unresponsiveness in the dexmedetomidine group resembled the large component evoked by incongruous stimuli at the awake baseline. After recovery, no recognition of the stimuli heard during unresponsiveness occurred. CONCLUSIONS Dexmedetomidine and propofol disrupt the discrimination of congruous and incongruous spoken sentences, and recognition memory at loss of responsiveness. However, the processing of words is partially preserved during dexmedetomidine-induced unresponsiveness. CLINICAL TRIAL REGISTRATION NCT01889004.
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Neural Signatures of the Processing of Temporal Patterns in Sound. J Neurosci 2018; 38:5466-5477. [PMID: 29773757 DOI: 10.1523/jneurosci.0346-18.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/13/2018] [Accepted: 05/06/2018] [Indexed: 11/21/2022] Open
Abstract
The ability to detect regularities in sound (i.e., recurring structure) is critical for effective perception, enabling, for example, change detection and prediction. Two seemingly unconnected lines of research concern the neural operations involved in processing regularities: one investigates how neural activity synchronizes with temporal regularities (e.g., frequency modulation; FM) in sounds, whereas the other focuses on increases in sustained activity during stimulation with repeating tone-frequency patterns. In three electroencephalography studies with male and female human participants, we investigated whether neural synchronization and sustained neural activity are dissociable, or whether they are functionally interdependent. Experiment I demonstrated that neural activity synchronizes with temporal regularity (FM) in sounds, and that sustained activity increases concomitantly. In Experiment II, phase coherence of FM in sounds was parametrically varied. Although neural synchronization was more sensitive to changes in FM coherence, such changes led to a systematic modulation of both neural synchronization and sustained activity, with magnitude increasing as coherence increased. In Experiment III, participants either performed a duration categorization task on the sounds, or a visual object tracking task to distract attention. Neural synchronization was observed regardless of task, whereas the sustained response was observed only when attention was on the auditory task, not under (visual) distraction. The results suggest that neural synchronization and sustained activity levels are functionally linked: both are sensitive to regularities in sounds. However, neural synchronization might reflect a more sensory-driven response to regularity, compared with sustained activity which may be influenced by attentional, contextual, or other experiential factors.SIGNIFICANCE STATEMENT Optimal perception requires that the auditory system detects regularities in sounds. Synchronized neural activity and increases in sustained neural activity both appear to index the detection of a regularity, but the functional interrelation of these two neural signatures is unknown. In three electroencephalography experiments, we measured both signatures concomitantly while listeners were presented with sounds containing frequency modulations that differed in their regularity. We observed that both neural signatures are sensitive to temporal regularity in sounds, although they functionally decouple when a listener is distracted by a demanding visual task. Our data suggest that neural synchronization reflects a more automatic response to regularity compared with sustained activity, which may be influenced by attentional, contextual, or other experiential factors.
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Koeritzer MA, Rogers CS, Van Engen KJ, Peelle JE. The Impact of Age, Background Noise, Semantic Ambiguity, and Hearing Loss on Recognition Memory for Spoken Sentences. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2018; 61:740-751. [PMID: 29450493 PMCID: PMC5963044 DOI: 10.1044/2017_jslhr-h-17-0077] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 08/28/2017] [Accepted: 09/20/2017] [Indexed: 05/20/2023]
Abstract
PURPOSE The goal of this study was to determine how background noise, linguistic properties of spoken sentences, and listener abilities (hearing sensitivity and verbal working memory) affect cognitive demand during auditory sentence comprehension. METHOD We tested 30 young adults and 30 older adults. Participants heard lists of sentences in quiet and in 8-talker babble at signal-to-noise ratios of +15 dB and +5 dB, which increased acoustic challenge but left the speech largely intelligible. Half of the sentences contained semantically ambiguous words to additionally manipulate cognitive challenge. Following each list, participants performed a visual recognition memory task in which they viewed written sentences and indicated whether they remembered hearing the sentence previously. RESULTS Recognition memory (indexed by d') was poorer for acoustically challenging sentences, poorer for sentences containing ambiguous words, and differentially poorer for noisy high-ambiguity sentences. Similar patterns were observed for Z-transformed response time data. There were no main effects of age, but age interacted with both acoustic clarity and semantic ambiguity such that older adults' recognition memory was poorer for acoustically degraded high-ambiguity sentences than the young adults'. Within the older adult group, exploratory correlation analyses suggested that poorer hearing ability was associated with poorer recognition memory for sentences in noise, and better verbal working memory was associated with better recognition memory for sentences in noise. CONCLUSIONS Our results demonstrate listeners' reliance on domain-general cognitive processes when listening to acoustically challenging speech, even when speech is highly intelligible. Acoustic challenge and semantic ambiguity both reduce the accuracy of listeners' recognition memory for spoken sentences. SUPPLEMENTAL MATERIALS https://doi.org/10.23641/asha.5848059.
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Affiliation(s)
- Margaret A Koeritzer
- Program in Audiology and Communication Sciences, Washington University in St. Louis, MO
| | - Chad S Rogers
- Department of Otolaryngology, Washington University in St. Louis, MO
| | - Kristin J Van Engen
- Department of Psychological and Brain Sciences and Program in Linguistics, Washington University in St. Louis, MO
| | - Jonathan E Peelle
- Department of Otolaryngology, Washington University in St. Louis, MO
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Alain C, Du Y, Bernstein LJ, Barten T, Banai K. Listening under difficult conditions: An activation likelihood estimation meta-analysis. Hum Brain Mapp 2018. [PMID: 29536592 DOI: 10.1002/hbm.24031] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The brain networks supporting speech identification and comprehension under difficult listening conditions are not well specified. The networks hypothesized to underlie effortful listening include regions responsible for executive control. We conducted meta-analyses of auditory neuroimaging studies to determine whether a common activation pattern of the frontal lobe supports effortful listening under different speech manipulations. Fifty-three functional neuroimaging studies investigating speech perception were divided into three independent Activation Likelihood Estimate analyses based on the type of speech manipulation paradigm used: Speech-in-noise (SIN, 16 studies, involving 224 participants); spectrally degraded speech using filtering techniques (15 studies involving 270 participants); and linguistic complexity (i.e., levels of syntactic, lexical and semantic intricacy/density, 22 studies, involving 348 participants). Meta-analysis of the SIN studies revealed higher effort was associated with activation in left inferior frontal gyrus (IFG), left inferior parietal lobule, and right insula. Studies using spectrally degraded speech demonstrated increased activation of the insula bilaterally and the left superior temporal gyrus (STG). Studies manipulating linguistic complexity showed activation in the left IFG, right middle frontal gyrus, left middle temporal gyrus and bilateral STG. Planned contrasts revealed left IFG activation in linguistic complexity studies, which differed from activation patterns observed in SIN or spectral degradation studies. Although there were no significant overlap in prefrontal activation across these three speech manipulation paradigms, SIN and spectral degradation showed overlapping regions in left and right insula. These findings provide evidence that there is regional specialization within the left IFG and differential executive networks underlie effortful listening.
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Affiliation(s)
- Claude Alain
- Rotman Research Institute, Baycrest Health Centre, Toronto, Ontario, Canada.,Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Yi Du
- CAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Lori J Bernstein
- Department of Supportive Care, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Thijs Barten
- Rotman Research Institute, Baycrest Health Centre, Toronto, Ontario, Canada
| | - Karen Banai
- Department of Communication Sciences and Disorders, University of Haifa, Haifa, Israel
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Mamach M, Wilke F, Durisin M, Beger FA, Finke M, Büchner A, Schultz B, Schultz A, Geworski L, Bengel FM, Lenarz T, Lesinski-Schiedat A, Berding G. Feasibility of 15O-water PET studies of auditory system activation during general anesthesia in children. EJNMMI Res 2018; 8:11. [PMID: 29404708 PMCID: PMC5799087 DOI: 10.1186/s13550-018-0362-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 01/11/2018] [Indexed: 11/10/2022] Open
Abstract
Background 15O-Water positron emission tomography (PET) enables functional imaging of the auditory system during stimulation via a promontory electrode or cochlear implant, which is not possible using functional magnetic resonance imaging (fMRI). Although PET has been introduced in this context decades ago, its feasibility when performed during general anesthesia has not yet been explored. However, due to a shift to earlier (and bilateral) auditory implantation, the need to study children during general anesthesia appeared, since they are not able to cooperate during scanning. Therefore, we evaluated retrospectively results of individual SPM (statistical parametric mapping) analysis of 15O-water PET in 17 children studied during general anesthesia and compared them to those in 9 adults studied while awake. Specifically, the influence of scan duration, smoothing filter kernel employed during preprocessing, and cut-off value used for statistical inferences were evaluated. Frequencies, peak heights, and extents of activations in auditory and extra-auditory brain regions (AR and eAR) were registered. Results It was possible to demonstrate activations in auditory brain regions during general anesthesia; however, the frequency and markedness of positive findings were dependent on some of the abovementioned influence factors. Scan duration (60 vs. 90 s) had no significant influence on peak height of auditory cortex activations. To achieve a similar frequency and extent of AR activations during general anesthesia compared to waking state, a lower cut-off for statistical inferences (p < 0.05 or p < 0.01 vs. p < 0.001) had to be applied. However, this lower cut-off was frequently associated with unexpected, “artificial” activations in eAR. These activations in eAR could be slightly reduced by the use of a stronger smoothing filter kernel during preprocessing of the data (e.g., [30 mm]3). Conclusions Our data indicate that it is feasible to detect auditory cortex activations in 15O-water PET during general anesthesia. Combined with the improved signal to noise ratios of modern PET scanners, this suggests reasonable prospects for further evaluation of the method for clinical use in auditory implant users. Adapted parameters for data analysis seem to be helpful to improve the proportion of signals in AR versus eAR.
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Affiliation(s)
- Martin Mamach
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.,Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany
| | - Florian Wilke
- Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany
| | - Martin Durisin
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Frank A Beger
- Department of Anesthesiology and Intensive Care Medicine, Hospital Diakovere Annastift, Hannover, Germany
| | - Mareike Finke
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.,Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Andreas Büchner
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.,Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Barbara Schultz
- Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, Hannover, Germany
| | - Arthur Schultz
- Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, Hannover, Germany
| | - Lilli Geworski
- Department of Medical Physics and Radiation Protection, Hannover Medical School, Hannover, Germany
| | - Frank M Bengel
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Thomas Lenarz
- Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.,Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | | | - Georg Berding
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.
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Timescales of Intrinsic BOLD Signal Dynamics and Functional Connectivity in Pharmacologic and Neuropathologic States of Unconsciousness. J Neurosci 2018; 38:2304-2317. [PMID: 29386261 PMCID: PMC5830518 DOI: 10.1523/jneurosci.2545-17.2018] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 12/14/2017] [Accepted: 01/24/2018] [Indexed: 01/09/2023] Open
Abstract
Environmental events are processed on multiple timescales via hierarchical organization of temporal receptive windows (TRWs) in the brain. The dependence of neural timescales and TRWs on altered states of consciousness is unclear. States of reduced consciousness are marked by a shift toward slowing of neural dynamics (<1 Hz) in EEG/ECoG signals. We hypothesize that such prolongation of intrinsic timescales are also seen in blood-oxygen-level-dependent (BOLD) signals. To test this hypothesis, we measured the timescales of intrinsic BOLD signals using mean frequency (MF) and temporal autocorrelation (AC) in healthy volunteers (n = 23; male/female 14/9) during graded sedation with propofol. We further examined the relationship between the intrinsic timescales (local/voxel level) and its regional connectivity (across neighboring voxels; regional homogeneity, ReHo), global (whole-brain level) functional connectivity (GFC), and topographical similarity (Topo). Additional results were obtained from patients undergoing deep general anesthesia (n = 12; male/female: 5/7) and in patients with disorders of consciousness (DOC) (n = 21; male/female: 14/7). We found that MF, AC, and ReHo increased, whereas GFC and Topo decreased, during propofol sedation. The local alterations occur before changes of distant connectivity. Conversely, all of these parameters decreased in deep anesthesia and in patients with DOC. We conclude that propofol synchronizes local neuronal interactions and prolongs the timescales of intrinsic BOLD signals. These effects may impede communication among distant brain regions. Furthermore, the intrinsic timescales exhibit distinct dynamic signatures in sedation, deep anesthesia, and DOC. These results improve our understanding of the neural mechanisms of unconsciousness in pharmacologic and neuropathologic states. SIGNIFICANCE STATEMENT Information processing in the brain occurs through a hierarchy of temporal receptive windows (TRWs) in multiple timescales. Anesthetic drugs induce a reversible suppression of consciousness and thus offer a unique opportunity to investigate the state dependence of neural timescales. Here, we demonstrate for the first time that sedation with propofol is accompanied by the prolongation of the timescales of intrinsic BOLD signals presumably reflecting enlarged TRWs. We show that this is accomplished by an increase of local and regional signal synchronization, effects that may disrupt information exchange among distant brain regions. Furthermore, we show that the timescales of intrinsic BOLD signals exhibit distinct dynamic signatures in sedation, deep anesthesia, and disorders of consciousness.
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