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Bleichner MG, Freudenburg ZV, Jansma JM, Aarnoutse EJ, Vansteensel MJ, Ramsey NF. Give me a sign: decoding four complex hand gestures based on high-density ECoG. Brain Struct Funct 2014; 221:203-16. [PMID: 25273279 PMCID: PMC4720726 DOI: 10.1007/s00429-014-0902-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 09/23/2014] [Indexed: 11/26/2022]
Abstract
The increasing understanding of human brain functions makes it possible to directly interact with the brain for therapeutic purposes. Implantable brain computer interfaces promise to replace or restore motor functions in patients with partial or complete paralysis. We postulate that neuronal states associated with gestures, as they are used in the finger spelling alphabet of sign languages, provide an excellent signal for implantable brain computer interfaces to restore communication. To test this, we evaluated decodability of four gestures using high-density electrocorticography in two participants. The electrode grids were located subdurally on the hand knob area of the sensorimotor cortex covering a surface of 2.5–5.2 cm2. Using a pattern-matching classification approach four types of hand gestures were classified based on their pattern of neuronal activity. In the two participants the gestures were classified with 97 and 74 % accuracy. The high frequencies (>65 Hz) allowed for the best classification results. This proof-of-principle study indicates that the four gestures are associated with a reliable and discriminable spatial representation on a confined area of the sensorimotor cortex. This robust representation on a small area makes hand gestures an interesting control feature for an implantable BCI to restore communication for severely paralyzed people.
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Affiliation(s)
- M G Bleichner
- UMC Utrecht Brain Center Rudolf Magnus, Utrecht, The Netherlands.
| | - Z V Freudenburg
- UMC Utrecht Brain Center Rudolf Magnus, Utrecht, The Netherlands.
| | - J M Jansma
- UMC Utrecht Brain Center Rudolf Magnus, Utrecht, The Netherlands.
| | - E J Aarnoutse
- UMC Utrecht Brain Center Rudolf Magnus, Utrecht, The Netherlands.
| | - M J Vansteensel
- UMC Utrecht Brain Center Rudolf Magnus, Utrecht, The Netherlands.
| | - N F Ramsey
- UMC Utrecht Brain Center Rudolf Magnus, Utrecht, The Netherlands.
- Universitair Medisch Centrum Utrecht, Heidelberglaan 100, 3584 CX, Huispost: G03.124, Utrecht, The Netherlands.
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152
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The role of resting state networks in focal neocortical seizures. PLoS One 2014; 9:e107401. [PMID: 25247680 PMCID: PMC4172478 DOI: 10.1371/journal.pone.0107401] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 08/16/2014] [Indexed: 11/19/2022] Open
Abstract
Objective The role of resting state functional networks in epilepsy is incompletely understood. While some pathologic diagnoses have been shown to have maintained but altered resting state connectivity, others have implicated resting state connectivity in disease progression. However little is known about how these resting state networks influence the behavior of a focal neocortical seizure. Methods Using data taken from invasively monitored patients with intractable focal neocortical epilepsy, we evaluated network connectivity (as determined by oscillatory covariance of the slow cortical potential (<0.5 Hz)) as it relates to neocortical seizure foci both in the interictal and ictal states. Results Similar to what has been shown in the past for sleep and anesthesia, electophysiologic resting state networks that are defined by this slow cortical potential covariance maintain their topographic correlation structure throughout an ictal event. Moreover, in the context of focal epilepsy in which the seizure has a specific site of onset, seizure propagation is not chaotic or random. Rather, the seizure (reflected by an elevation of high frequency power) preferentially propagates along the network that contains the seizure onset zone. Significance Taken together, these findings further undergird the fundamental role of resting state networks, provide novel insights into the network-influenced behavior of seizures, and potentially identify additional targets for surgical disconnection including informing the location for the completion of multiple subpial transections (MSPTs).
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153
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Blakely TM, Olson JD, Miller KJ, Rao RPN, Ojemann JG. Neural correlates of learning in an electrocorticographic motor-imagery brain-computer interface. BRAIN-COMPUTER INTERFACES 2014; 1:147-157. [PMID: 25599079 DOI: 10.1080/2326263x.2014.954183] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Human subjects can learn to control a one-dimensional electrocorticographic (ECoG) brain-computer interface (BCI) using modulation of primary motor (M1) high-gamma activity (signal power in the 75-200 Hz range). However, the stability and dynamics of the signals over the course of new BCI skill acquisition have not been investigated. In this study, we report 3 characteristic periods in evolution of the high-gamma control signal during BCI training: initial, low task accuracy with corresponding low power modulation in the gamma spectrum, followed by a second period of improved task accuracy with increasing average power separation between activity and rest, and a final period of high task accuracy with stable (or decreasing) power separation and decreasing trial-to-trial variance. These findings may have implications in the design and implementation of BCI control algorithms.
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Affiliation(s)
- Tim M Blakely
- Department of Bioengineering, University of Washington, Seattle WA, 2419 8th Ave N Apt 402, Seattle, WA 98109. This author's research studies the underlying cortical organization of human sensorimotor function, specializing in multi-day micro-electrocorticographic array recordings in human subjects. This type of research is applicable in many areas of cognitive neuroscience, from brain-computer interfacing to neural engineering and robotics
| | - Jared D Olson
- Department of Rehabilitation Medicine, University of Washington, Seattle, WA. Center for Sensorimotor Neural Engineering, Seattle, WA, Box 359740, 325 9 Avenue, Seattle, WA 98104, 206-744-5862, The author researches human sensorimotor neurophysiology, clinical translation of brain-machine interfaces, and is a physiatrist (physical medicine and rehabilitation physician) specializing in neurorehabilitation
| | - Kai J Miller
- Prior Affiliation: Department of Neurobiology and Behavior, University of Washington, Seattle, WA. Current Affiliation: Department of Neurological Surgery, Stanford School of Medicine, Stanford, CA, 300 Pasteur Drive, Stanford, CA 94305-5327, Kai is interested in distributed brain dynamics and systems neuroscience, and is currently in a neurosurgery residency
| | - Rajesh P N Rao
- Center for Sensorimotor Neural Engineering, Seattle, WA. Department of Computer Science and Engineering, University of Washington, Box 352350, Seattle, WA 98195, (206) 685-9141. The author's research spans the areas of brain-computer interfacing, computational neuroscience and robotics
| | - Jeffrey G Ojemann
- Neurological Surgery and Radiology, University of Washington, Center for Sensorimotor Neural Engineering, Seattle, WA, Center for Integrative Brain Research, Seattle Children's Research Institute, Box 359300, Seattle, WA 98195, (206) 987-4240. This author's research is electrocorticographic studies of cognitive function and brain-machine interface and is a neurosurgeon specializing in the treatment of pediatric and epilepsy neurosurgery
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154
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Resting-state blood oxygen level-dependent functional magnetic resonance imaging for presurgical planning. Neuroimaging Clin N Am 2014; 24:655-69. [PMID: 25441506 DOI: 10.1016/j.nic.2014.07.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Resting-state functional MR imaging (rsfMR imaging) measures spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal and can be used to elucidate the brain's functional organization. It is used to simultaneously assess multiple distributed resting-state networks. Unlike task-based functional MR imaging, rsfMR imaging does not require task performance. This article presents a brief introduction of rsfMR imaging processing methods followed by a detailed discussion on the use of rsfMR imaging in presurgical planning. Example cases are provided to highlight the strengths and limitations of the technique.
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155
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Szczepanski SM, Crone NE, Kuperman RA, Auguste KI, Parvizi J, Knight RT. Dynamic changes in phase-amplitude coupling facilitate spatial attention control in fronto-parietal cortex. PLoS Biol 2014; 12:e1001936. [PMID: 25157678 PMCID: PMC4144794 DOI: 10.1371/journal.pbio.1001936] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/18/2014] [Indexed: 11/18/2022] Open
Abstract
Electrocorticography reveals how coupling between two frequencies of neuronal oscillation allows the frontal and parietal areas of the cortex to control visual attention from moment to moment in the human brain. Attention is a core cognitive mechanism that allows the brain to allocate limited resources depending on current task demands. A number of frontal and posterior parietal cortical areas, referred to collectively as the fronto-parietal attentional control network, are engaged during attentional allocation in both humans and non-human primates. Numerous studies have examined this network in the human brain using various neuroimaging and scalp electrophysiological techniques. However, little is known about how these frontal and parietal areas interact dynamically to produce behavior on a fine temporal (sub-second) and spatial (sub-centimeter) scale. We addressed how human fronto-parietal regions control visuospatial attention on a fine spatiotemporal scale by recording electrocorticography (ECoG) signals measured directly from subdural electrode arrays that were implanted in patients undergoing intracranial monitoring for localization of epileptic foci. Subjects (n = 8) performed a spatial-cuing task, in which they allocated visuospatial attention to either the right or left visual field and detected the appearance of a target. We found increases in high gamma (HG) power (70–250 Hz) time-locked to trial onset that remained elevated throughout the attentional allocation period over frontal, parietal, and visual areas. These HG power increases were modulated by the phase of the ongoing delta/theta (2–5 Hz) oscillation during attentional allocation. Critically, we found that the strength of this delta/theta phase-HG amplitude coupling predicted reaction times to detected targets on a trial-by-trial basis. These results highlight the role of delta/theta phase-HG amplitude coupling as a mechanism for sub-second facilitation and coordination within human fronto-parietal cortex that is guided by momentary attentional demands. The frontal and parietal areas of the cortex control the ability to focus visuospatial attention, and damage to these areas results in profound attentional disturbances. Although much research has concentrated on where these areas are located, little is known about how these areas may function in humans. Previous studies have demonstrated that neuronal spiking is more likely to occur in specific time windows based upon the phase of lower frequency neural oscillations – rhythmic or repetitive neuronal activity. These low-frequency rhythms are hypothesized to coordinate the timing of neuronal firing within local and across network regions. Here, we investigated how human frontal and parietal cortices use neural oscillations to control visuospatial attention. We identified a high-frequency component of electrical brain activity, broadband high gamma (70–250 Hz) amplitude, that became phase-locked to a slower rhythm, delta/theta (2–5 Hz), over frontal, parietal, and visual areas while the study subjects paid attention to the peripheral visual field. Changes in the strength of the coupling between delta/theta phase and high gamma amplitude predicted the attentional behavior of the subjects across single trials. From these results, we conclude that coupling between delta/theta phase and high gamma amplitude serves to coordinate information within – and perhaps between – frontal and parietal areas during allocation of visuospatial attention.
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Affiliation(s)
- Sara M. Szczepanski
- Department of Psychology, University of California, Berkeley, Berkeley, California, United States of America
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
| | - Nathan E. Crone
- Department of Neurology, Epilepsy Center, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Rachel A. Kuperman
- Department of Neurology, Children's Hospital and Research Center, Oakland, Oakland, California, United States of America
| | - Kurtis I. Auguste
- Department of Surgery, Division of Neurological Surgery, Children's Hospital and Research Center, Oakland, Oakland, California, United States of America
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California, United States of America
| | - Josef Parvizi
- Laboratory of Behavioral and Cognitive Neurology, Department of Neurology and Neurological Sciences, Stanford University, Stanford, California, United States of America
- Stanford Human Intracranial Cognitive Electrophysiology Program (SHICEP), Stanford University, Stanford, California, United States of America
| | - Robert T. Knight
- Department of Psychology, University of California, Berkeley, Berkeley, California, United States of America
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, United States of America
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156
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Gupta D, Hill NJ, Adamo MA, Ritaccio A, Schalk G. Localizing ECoG electrodes on the cortical anatomy without post-implantation imaging. Neuroimage Clin 2014; 6:64-76. [PMID: 25379417 PMCID: PMC4215521 DOI: 10.1016/j.nicl.2014.07.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 07/26/2014] [Accepted: 07/29/2014] [Indexed: 01/22/2023]
Abstract
INTRODUCTION Electrocorticographic (ECoG) grids are placed subdurally on the cortex in people undergoing cortical resection to delineate eloquent cortex. ECoG signals have high spatial and temporal resolution and thus can be valuable for neuroscientific research. The value of these data is highest when they can be related to the cortical anatomy. Existing methods that establish this relationship rely either on post-implantation imaging using computed tomography (CT), magnetic resonance imaging (MRI) or X-Rays, or on intra-operative photographs. For research purposes, it is desirable to localize ECoG electrodes on the brain anatomy even when post-operative imaging is not available or when intra-operative photographs do not readily identify anatomical landmarks. METHODS We developed a method to co-register ECoG electrodes to the underlying cortical anatomy using only a pre-operative MRI, a clinical neuronavigation device (such as BrainLab VectorVision), and fiducial markers. To validate our technique, we compared our results to data collected from six subjects who also had post-grid implantation imaging available. We compared the electrode coordinates obtained by our fiducial-based method to those obtained using existing methods, which are based on co-registering pre- and post-grid implantation images. RESULTS Our fiducial-based method agreed with the MRI-CT method to within an average of 8.24 mm (mean, median = 7.10 mm) across 6 subjects in 3 dimensions. It showed an average discrepancy of 2.7 mm when compared to the results of the intra-operative photograph method in a 2D coordinate system. As this method does not require post-operative imaging such as CTs, our technique should prove useful for research in intra-operative single-stage surgery scenarios. To demonstrate the use of our method, we applied our method during real-time mapping of eloquent cortex during a single-stage surgery. The results demonstrated that our method can be applied intra-operatively in the absence of post-operative imaging to acquire ECoG signals that can be valuable for neuroscientific investigations.
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Affiliation(s)
- Disha Gupta
- Dept. of Neurology, Albany Medical College, Albany, NY, USA
- Neural Injury and Repair, Wadsworth Center, New York State Dept. of Health, Albany, NY, USA
- Early Brain Injury and Motor Recovery Lab, Burke-Cornell Medical Research Institute, White Plains, NY, USA
| | - N. Jeremy Hill
- Neural Injury and Repair, Wadsworth Center, New York State Dept. of Health, Albany, NY, USA
- Translational Neurological Research Laboratory, Helen Hayes Hospital, West Haverstraw, NY, USA
| | | | | | - Gerwin Schalk
- Dept. of Neurology, Albany Medical College, Albany, NY, USA
- Neural Injury and Repair, Wadsworth Center, New York State Dept. of Health, Albany, NY, USA
- Dept. of Neurosurgery, Washington University, St. Louis, MO, USA
- Dept. of Biomed. Eng., Rensselaer Polytechnic Institute, Troy, NY, USA
- Dept. of Biomed. Sci., State Univ. of New York at Albany, Albany, NY, USA
- Dept. of Elec. and Comp. Eng., Univ. of Texas at El Paso, El Paso, TX, USA
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157
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Singer N, Podlipsky I, Esposito F, Okon-Singer H, Andelman F, Kipervasser S, Neufeld MY, Goebel R, Fried I, Hendler T. Distinct iEEG activity patterns in temporal-limbic and prefrontal sites induced by emotional intentionality. Cortex 2014; 60:121-38. [PMID: 25288171 DOI: 10.1016/j.cortex.2014.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 04/09/2014] [Accepted: 07/29/2014] [Indexed: 12/30/2022]
Abstract
Our emotions tend to be directed towards someone or something. Such emotional intentionality calls for the integration between two streams of information; abstract hedonic value and its associated concrete content. In a previous functional magnetic resonance imaging (fMRI) study we found that the combination of these two streams, as modeled by short emotional music excerpts and neutral film clips, was associated with synergistic activation in both temporal-limbic (TL) and ventral-lateral PFC (vLPFC) regions. This additive effect implies the integration of domain-specific 'affective' and 'cognitive' processes. Yet, the low temporal resolution of the fMRI limits the characterization of such cross-domain integration. To this end, we complemented the fMRI data with intracranial electroencephalogram (iEEG) recordings from twelve patients with intractable epilepsy. As expected, the additive fMRI activation in the amygdala and vLPFC was associated with distinct spatio-temporal iEEG patterns among electrodes situated within the vicinity of the fMRI activation foci. On the one hand, TL channels exhibited a transient (0-500 msec) increase in gamma power (61-69 Hz), possibly reflecting initial relevance detection or hedonic value tagging. On the other hand, vLPFC channels showed sustained (1-12 sec) suppression of low frequency power (2.3-24 Hz), possibly mediating changes in gating, enabling an on-going readiness for content-based processing of emotionally tagged signals. Moreover, an additive effect in delta-gamma phase-amplitude coupling (PAC) was found among the TL channels, possibly reflecting the integration between distinct domain specific processes. Together, this study provides a multi-faceted neurophysiological signature for computations that possibly underlie emotional intentionality in humans.
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Affiliation(s)
- Neomi Singer
- Functional Brain Center, Wohl Institute for Advanced Imaging, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel; Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel; School of Psychological Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Ilana Podlipsky
- Functional Brain Center, Wohl Institute for Advanced Imaging, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
| | - Fabrizio Esposito
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Medicine and Surgery, University of Salerno, Baronissi (SA), Italy
| | - Hadas Okon-Singer
- Functional Brain Center, Wohl Institute for Advanced Imaging, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
| | - Fani Andelman
- Functional Neurosurgery Unit, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
| | - Svetlana Kipervasser
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Epilepsy Unit, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
| | - Miri Y Neufeld
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Epilepsy Unit, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel
| | - Rainer Goebel
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Itzhak Fried
- Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; Functional Neurosurgery Unit, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel; Division of Neurosurgery, David Geffen School of Medicine and Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, USA
| | - Talma Hendler
- Functional Brain Center, Wohl Institute for Advanced Imaging, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel; Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel; School of Psychological Sciences, Tel-Aviv University, Tel-Aviv, Israel; Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
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158
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Flint RD, Wang PT, Wright ZA, King CE, Krucoff MO, Schuele SU, Rosenow JM, Hsu FPK, Liu CY, Lin JJ, Sazgar M, Millett DE, Shaw SJ, Nenadic Z, Do AH, Slutzky MW. Extracting kinetic information from human motor cortical signals. Neuroimage 2014; 101:695-703. [PMID: 25094020 DOI: 10.1016/j.neuroimage.2014.07.049] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 06/06/2014] [Accepted: 07/22/2014] [Indexed: 11/29/2022] Open
Abstract
Brain machine interfaces (BMIs) have the potential to provide intuitive control of neuroprostheses to restore grasp to patients with paralyzed or amputated upper limbs. For these neuroprostheses to function, the ability to accurately control grasp force is critical. Grasp force can be decoded from neuronal spikes in monkeys, and hand kinematics can be decoded using electrocorticogram (ECoG) signals recorded from the surface of the human motor cortex. We hypothesized that kinetic information about grasping could also be extracted from ECoG, and sought to decode continuously-graded grasp force. In this study, we decoded isometric pinch force with high accuracy from ECoG in 10 human subjects. The predicted signals explained from 22% to 88% (60 ± 6%, mean ± SE) of the variance in the actual force generated. We also decoded muscle activity in the finger flexors, with similar accuracy to force decoding. We found that high gamma band and time domain features of the ECoG signal were most informative about kinetics, similar to our previous findings with intracortical LFPs. In addition, we found that peak cortical representations of force applied by the index and little fingers were separated by only about 4mm. Thus, ECoG can be used to decode not only kinematics, but also kinetics of movement. This is an important step toward restoring intuitively-controlled grasp to impaired patients.
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Affiliation(s)
- Robert D Flint
- Department of Neurology, Northwestern University, Chicago, IL 60611, USA.
| | - Po T Wang
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617, USA
| | - Zachary A Wright
- Department of Neurology, Northwestern University, Chicago, IL 60611, USA
| | - Christine E King
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617, USA
| | - Max O Krucoff
- Division of Neurosurgery, Duke University, Durham, NC, USA
| | - Stephan U Schuele
- Department of Neurology, Northwestern University, Chicago, IL 60611, USA
| | - Joshua M Rosenow
- Department of Neurosurgery, Northwestern University, Chicago, IL 60611, USA
| | - Frank P K Hsu
- Department of Neurosurgery, University of California, Irvine, Irvine, CA 92617, USA
| | - Charles Y Liu
- Department of Neurosurgery, Rancho Los Amigos National Rehabilitation Center, Downey, CA 90242, USA; Department of Neurosurgery, University of Southern California, Los Angeles, CA 90033, USA
| | - Jack J Lin
- Department of Neurology, University of California, Irvine, Irvine, CA 92617, USA
| | - Mona Sazgar
- Department of Neurology, University of California, Irvine, Irvine, CA 92617, USA
| | - David E Millett
- Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA 90242, USA; Department of Neurology, University of Southern California, Los Angeles, CA 90033, USA
| | - Susan J Shaw
- Department of Neurology, Rancho Los Amigos National Rehabilitation Center, Downey, CA 90242, USA; Department of Neurology, University of Southern California, Los Angeles, CA 90033, USA
| | - Zoran Nenadic
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617, USA; Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, CA 92617, USA
| | - An H Do
- Department of Neurology, University of California, Irvine, Irvine, CA 92617, USA
| | - Marc W Slutzky
- Department of Neurology, Northwestern University, Chicago, IL 60611, USA; Department of Physiology, Northwestern University, Chicago, IL 60611, USA; Department of Physical Medicine & Rehabilitation, Northwestern University, Chicago, IL 60611, USA; The Rehabilitation Institute of Chicago, Chicago, IL 60611, USA
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159
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Mitchell TJ, Hacker CD, Breshears JD, Szrama NP, Sharma M, Bundy DT, Pahwa M, Corbetta M, Snyder AZ, Shimony JS, Leuthardt EC. A novel data-driven approach to preoperative mapping of functional cortex using resting-state functional magnetic resonance imaging. Neurosurgery 2014; 73:969-82; discussion 982-3. [PMID: 24264234 PMCID: PMC3871406 DOI: 10.1227/neu.0000000000000141] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Supplemental Digital Content is Available in the Text. BACKGROUND: Recent findings associated with resting-state cortical networks have provided insight into the brain's organizational structure. In addition to their neuroscientific implications, the networks identified by resting-state functional magnetic resonance imaging (rs-fMRI) may prove useful for clinical brain mapping. OBJECTIVE: To demonstrate that a data-driven approach to analyze resting-state networks (RSNs) is useful in identifying regions classically understood to be eloquent cortex as well as other functional networks. METHODS: This study included 6 patients undergoing surgical treatment for intractable epilepsy and 7 patients undergoing tumor resection. rs-fMRI data were obtained before surgery and 7 canonical RSNs were identified by an artificial neural network algorithm. Of these 7, the motor and language networks were then compared with electrocortical stimulation (ECS) as the gold standard in the epilepsy patients. The sensitivity and specificity for identifying these eloquent sites were calculated at varying thresholds, which yielded receiver-operating characteristic (ROC) curves and their associated area under the curve (AUC). RSNs were plotted in the tumor patients to observe RSN distortions in altered anatomy. RESULTS: The algorithm robustly identified all networks in all patients, including those with distorted anatomy. When all ECS-positive sites were considered for motor and language, rs-fMRI had AUCs of 0.80 and 0.64, respectively. When the ECS-positive sites were analyzed pairwise, rs-fMRI had AUCs of 0.89 and 0.76 for motor and language, respectively. CONCLUSION: A data-driven approach to rs-fMRI may be a new and efficient method for preoperative localization of numerous functional brain regions. ABBREVIATIONS: AUC, area under the curve BA, Brodmann area BOLD, blood oxygen level dependent ECS, electrocortical stimulation fMRI, functional magnetic resonance imaging ICA, independent component analysis MLP, multilayer perceptron MP-RAGE, magnetization-prepared rapid gradient echo ROC, receiver-operating characteristic rs-fMRI, resting-state functional magnetic resonance imaging RSN, resting-state network
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Affiliation(s)
- Timothy J Mitchell
- Departments of *Neurological Surgery, ‡Neurology, §Biomedical Engineering, and ¶Mechanical Engineering and Material Sciences, ‖Mallinckrodt Institute of Radiology, #Center for Innovation in Neuroscience and Technology, Washington University School of Medicine, St. Louis, Missouri
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160
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Vansteensel MJ, Bleichner MG, Freudenburg ZV, Hermes D, Aarnoutse EJ, Leijten FSS, Ferrier CH, Jansma JM, Ramsey NF. Spatiotemporal characteristics of electrocortical brain activity during mental calculation. Hum Brain Mapp 2014; 35:5903-20. [PMID: 25044370 DOI: 10.1002/hbm.22593] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 06/16/2014] [Accepted: 07/14/2014] [Indexed: 11/08/2022] Open
Abstract
Mental calculation is a complex mental procedure involving a frontoparietal network of brain regions. Functional MRI (fMRI) studies have revealed interesting characteristics of these regions, but the precise function of some areas remains elusive. In the present study, we used electrocorticographic (ECoG) recordings to chronometrically assess the neuronal processes during mental arithmetic. A calculation task was performed during presurgical 3T fMRI scanning and subsequent ECoG monitoring. Mental calculation induced an increase in fMRI blood oxygen level dependent signal in prefrontal, parietal and lower temporo-occipital regions. The group-fMRI result was subsequently used to cluster the implanted electrodes into anatomically defined regions of interest (ROIs). We observed remarkable differences in high frequency power profiles between ROIs, some of which were closely associated with stimulus presentation and others with the response. Upon stimulus presentation, occipital areas were the first to respond, followed by parietal and frontal areas, and finally by motor areas. Notably, we demonstrate that the fMRI activation in the middle frontal gyrus/precentral gyrus is associated with two subfunctions during mental calculation. This finding reveals the significance of the temporal dynamics of neural ensembles within regions with an apparent uniform function. In conclusion, our results shed more light on the spatiotemporal aspects of brain activation during a mental calculation task, and demonstrate that the use of fMRI data to cluster ECoG electrodes is a useful approach for ECoG group analysis.
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Affiliation(s)
- Mariska J Vansteensel
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
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161
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Kadipasaoglu CM, Baboyan VG, Conner CR, Chen G, Saad ZS, Tandon N. Surface-based mixed effects multilevel analysis of grouped human electrocorticography. Neuroimage 2014; 101:215-24. [PMID: 25019677 DOI: 10.1016/j.neuroimage.2014.07.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 06/21/2014] [Accepted: 07/06/2014] [Indexed: 10/25/2022] Open
Abstract
Electrocorticography (ECoG) in humans yields data with unmatched spatio-temporal resolution that provides novel insights into cognitive operations. However, the broader application of ECoG has been confounded by difficulties in accurately depicting individual data and performing statistically valid population-level analyses. To overcome these limitations, we developed methods for accurately registering ECoG data to individual cortical topology. We integrated this technique with surface-based co-registration and a mixed-effects multilevel analysis (MEMA) to control for variable cortical surface anatomy and sparse coverage across patients, as well as intra- and inter-subject variability. We applied this surface-based MEMA (SB-MEMA) technique to a face-recognition task dataset (n=22). Compared against existing techniques, SB-MEMA yielded results much more consistent with individual data and with meta-analyses of face-specific activation studies. We anticipate that SB-MEMA will greatly expand the role of ECoG in studies of human cognition, and will enable the generation of population-level brain activity maps and accurate multimodal comparisons.
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Affiliation(s)
- C M Kadipasaoglu
- Vivian Smith Department of Neurosurgery, Univ. of Texas Medical School at Houston, 6431 Fannin Street, Suite G.550D, Houston, TX 77030, USA
| | - V G Baboyan
- Vivian Smith Department of Neurosurgery, Univ. of Texas Medical School at Houston, 6431 Fannin Street, Suite G.550D, Houston, TX 77030, USA
| | - C R Conner
- Vivian Smith Department of Neurosurgery, Univ. of Texas Medical School at Houston, 6431 Fannin Street, Suite G.550D, Houston, TX 77030, USA
| | - G Chen
- Scientific and Statistical Computing Core, NIMH/NIH/DHHS, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Z S Saad
- Scientific and Statistical Computing Core, NIMH/NIH/DHHS, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - N Tandon
- Vivian Smith Department of Neurosurgery, Univ. of Texas Medical School at Houston, 6431 Fannin Street, Suite G.550D, Houston, TX 77030, USA; Memorial Hermann Hospital, Texas Medical Center, Houston, TX 77030, USA.
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162
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Mugler EM, Patton JL, Flint RD, Wright ZA, Schuele SU, Rosenow J, Shih JJ, Krusienski DJ, Slutzky MW. Direct classification of all American English phonemes using signals from functional speech motor cortex. J Neural Eng 2014; 11:035015. [PMID: 24836588 PMCID: PMC4097188 DOI: 10.1088/1741-2560/11/3/035015] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Although brain-computer interfaces (BCIs) can be used in several different ways to restore communication, communicative BCI has not approached the rate or efficiency of natural human speech. Electrocorticography (ECoG) has precise spatiotemporal resolution that enables recording of brain activity distributed over a wide area of cortex, such as during speech production. In this study, we sought to decode elements of speech production using ECoG. APPROACH We investigated words that contain the entire set of phonemes in the general American accent using ECoG with four subjects. Using a linear classifier, we evaluated the degree to which individual phonemes within each word could be correctly identified from cortical signal. MAIN RESULTS We classified phonemes with up to 36% accuracy when classifying all phonemes and up to 63% accuracy for a single phoneme. Further, misclassified phonemes follow articulation organization described in phonology literature, aiding classification of whole words. Precise temporal alignment to phoneme onset was crucial for classification success. SIGNIFICANCE We identified specific spatiotemporal features that aid classification, which could guide future applications. Word identification was equivalent to information transfer rates as high as 3.0 bits s(-1) (33.6 words min(-1)), supporting pursuit of speech articulation for BCI control.
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Affiliation(s)
- Emily M Mugler
- Bioengineering, University of Illinois at Chicago, 851 S. Morgan Street, Chicago, IL 60607, USA
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163
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Hermes D, Miller KJ, Wandell BA, Winawer J. Stimulus Dependence of Gamma Oscillations in Human Visual Cortex. Cereb Cortex 2014; 25:2951-9. [PMID: 24855114 DOI: 10.1093/cercor/bhu091] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A striking feature of some field potential recordings in visual cortex is a rhythmic oscillation within the gamma band (30-80 Hz). These oscillations have been proposed to underlie computations in perception, attention, and information transmission. Recent studies of cortical field potentials, including human electrocorticography (ECoG), have emphasized another signal within the gamma band, a nonoscillatory, broadband signal, spanning 80-200 Hz. It remains unclear under what conditions gamma oscillations are elicited in visual cortex, whether they are necessary and ubiquitous in visual encoding, and what relationship they have to nonoscillatory, broadband field potentials. We demonstrate that ECoG responses in human visual cortex (V1/V2/V3) can include robust narrowband gamma oscillations, and that these oscillations are reliably elicited by some spatial contrast patterns (luminance gratings) but not by others (noise patterns and many natural images). The gamma oscillations can be conspicuous and robust, but because they are absent for many stimuli, which observers can see and recognize, the oscillations are not necessary for seeing. In contrast, all visual stimuli induced broadband spectral changes in ECoG responses. Asynchronous neural signals in visual cortex, reflected in the broadband ECoG response, can support transmission of information for perception and recognition in the absence of pronounced gamma oscillations.
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Affiliation(s)
- D Hermes
- Department of Psychology, New York University, New York, NY, USA Department of Psychology, Stanford University, Stanford, CA, USA
| | - K J Miller
- Department of Neurosurgery, Stanford University, Stanford, CA, USA Program in Neurobiology and Behavior, University of Washington, Seattle, WA, USA
| | - B A Wandell
- Department of Psychology, Stanford University, Stanford, CA, USA
| | - J Winawer
- Department of Psychology, New York University, New York, NY, USA Center for Neural Science, New York University, New York, NY, USA
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164
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Sachs AJ, Babu H, Su YF, Miller KJ, Henderson JM. Lack of efficacy of motor cortex stimulation for the treatment of neuropathic pain in 14 patients. Neuromodulation 2014; 17:303-10; discussion 310-1. [PMID: 24773411 DOI: 10.1111/ner.12181] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/31/2013] [Accepted: 01/22/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Motor cortex stimulation has been reported as an effective treatment for medically resistant neuropathic pain. The goal of this study is to review the efficacy of this treatment in a series of 14 patients. MATERIALS AND METHODS The records of a consecutive series of 14 patients undergoing MCS for neuropathic pain at Stanford University Hospital and Clinics between 2002 and 2010 were retrospectively analyzed. The primary outcome measure was a visual analogue scale, which patients completed prior to surgery and following each programming session. The motor cortex was localized using 1) MR image guidance, 2) intraoperative somatosensory evoked potentials and motor response to stimulation, and 3) postoperative imaging. All patients underwent extensive stimulator programming. RESULTS Five patients exhibited a transient improvement of >50%. Of these, only two patients maintained >50% improvement to their last clinic visit. One of these patients died of unrelated causes, and the other complained of variable response at home. The median time from best to final VAS was 50 days. Average postoperative follow-up was 55.5 weeks. Postoperative imaging demonstrated appropriate lead placement in 12 patients. The other two patients did not undergo postoperative imaging. CONCLUSIONS In our cohort of 14 patients with neuropathic pain, motor cortex stimulation failed to produce acceptable long-term benefit. Possible reasons for this failure are discussed in the context of a small retrospective study.
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Affiliation(s)
- Adam J Sachs
- Division of Neurosurgery, Department of Surgery, The Ottawa Hospital Research Institute, The University of Ottawa, Ottawa, Ontario, Canada
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165
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Miller KJ, Honey CJ, Hermes D, Rao RPN, denNijs M, Ojemann JG. Broadband changes in the cortical surface potential track activation of functionally diverse neuronal populations. Neuroimage 2014; 85 Pt 2:711-20. [PMID: 24018305 PMCID: PMC4347924 DOI: 10.1016/j.neuroimage.2013.08.070] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 08/23/2013] [Accepted: 08/29/2013] [Indexed: 11/18/2022] Open
Abstract
We illustrate a general principal of electrical potential measurements from the surface of the cerebral cortex, by revisiting and reanalyzing experimental work from the visual, language and motor systems. A naive decomposition technique of electrocorticographic power spectral measurements reveals that broadband spectral changes reliably track task engagement. These broadband changes are shown to be a generic correlate of local cortical function across a variety of brain areas and behavioral tasks. Furthermore, they fit a power-law form that is consistent with simple models of the dendritic integration of asynchronous local population firing. Because broadband spectral changes covary with diverse perceptual and behavioral states on the timescale of 20-50 ms, they provide a powerful and widely applicable experimental tool.
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Affiliation(s)
- Kai J Miller
- Department of Neurosurgery, Stanford University, Stanford, CA, USA; Program in Neurobiology and Behavior, University of Washington, Seattle, WA, USA
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166
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Rowland NC, Miller KJ, Starr PA. Three-Dimensional Accuracy of ECOG Strip Electrode Localization Using Coregistration of Preoperative MRI and Intraoperative Fluoroscopy. Stereotact Funct Neurosurg 2014; 92:8-16. [DOI: 10.1159/000350027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 02/19/2013] [Indexed: 11/19/2022]
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167
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Princich JP, Wassermann D, Latini F, Oddo S, Blenkmann AO, Seifer G, Kochen S. Rapid and efficient localization of depth electrodes and cortical labeling using free and open source medical software in epilepsy surgery candidates. Front Neurosci 2013; 7:260. [PMID: 24427112 PMCID: PMC3876273 DOI: 10.3389/fnins.2013.00260] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 12/11/2013] [Indexed: 11/23/2022] Open
Abstract
Depth intracranial electrodes (IEs) placement is one of the most used procedures to identify the epileptogenic zone (EZ) in surgical treatment of drug resistant epilepsy patients, about 20–30% of this population. IEs localization is therefore a critical issue defining the EZ and its relation with eloquent functional areas. That information is then used to target the resective surgery and has great potential to affect outcome. We designed a methodological procedure intended to avoid the need for highly specialized medical resources and reduce time to identify the anatomical location of IEs, during the first instances of intracranial EEG recordings. This workflow is based on established open source software; 3D Slicer and Freesurfer that uses MRI and Post-implant CT fusion for the localization of IEs and its relation with automatic labeled surrounding cortex. To test this hypothesis we assessed the time elapsed between the surgical implantation process and the final anatomical localization of IEs by means of our proposed method compared against traditional visual analysis of raw post-implant imaging in two groups of patients. All IEs were identified in the first 24 H (6–24 H) of implantation using our method in 4 patients of the first group. For the control group; all IEs were identified by experts with an overall time range of 36 h to 3 days using traditional visual analysis. It included (7 patients), 3 patients implanted with IEs and the same 4 patients from the first group. Time to localization was restrained in this group by the specialized personnel and the image quality available. To validate our method; we trained two inexperienced operators to assess the position of IEs contacts on four patients (5 IEs) using the proposed method. We quantified the discrepancies between operators and we also assessed the efficiency of our method to define the EZ comparing the findings against the results of traditional analysis.
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Affiliation(s)
- Juan Pablo Princich
- Epilepsy Section, Neurosciences Clinic and Applicated Center, Hospital Ramos Mejia, Universidad de Buenos Aires Buenos Aires, Argentina ; Fundación Favaloro, Resonancia Magnética, Neuroimágenes Buenos Aires, Argentina ; Imágenes Médicas -Neuroimágenes, Resonancia Magnética, Hospital de Pediatría SAMIC Prof. Dr. Juan Pedro Garrahan Buenos Aires, Argentina
| | - Demian Wassermann
- Department of Radiology, Harvard Medical School, Brigham and Women's Hospital Boston, MA, USA
| | - Facundo Latini
- Epilepsy Section, Neurosciences Clinic and Applicated Center, Hospital Ramos Mejia, Universidad de Buenos Aires Buenos Aires, Argentina
| | - Silvia Oddo
- Epilepsy Section, Neurosciences Clinic and Applicated Center, Hospital Ramos Mejia, Universidad de Buenos Aires Buenos Aires, Argentina
| | - Alejandro Omar Blenkmann
- Epilepsy Section, Neurosciences Clinic and Applicated Center, Hospital Ramos Mejia, Universidad de Buenos Aires Buenos Aires, Argentina
| | - Gustavo Seifer
- Epilepsy Section, Neurosciences Clinic and Applicated Center, Hospital Ramos Mejia, Universidad de Buenos Aires Buenos Aires, Argentina
| | - Silvia Kochen
- Epilepsy Section, Neurosciences Clinic and Applicated Center, Hospital Ramos Mejia, Universidad de Buenos Aires Buenos Aires, Argentina
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168
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Lee C, Kim JS, Jeong W, Chung CK. Usefulness of interictal spike source localization in temporal lobe epilepsy: electrocorticographic study. Epilepsy Res 2013; 108:448-58. [PMID: 24434002 DOI: 10.1016/j.eplepsyres.2013.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 11/19/2013] [Accepted: 12/05/2013] [Indexed: 11/15/2022]
Abstract
The success of epilepsy surgery depends on delineation of the suspected epileptogenic zone. The gold standard to delineate it is to use the ictal onset zone from an electrocorticography (ECoG). Although interictal spikes are also associated with the epileptogenic zone, their clinical significance has been under-evaluated. The aim of this study was to evaluate the source localization of interictal spikes in terms of the association with epileptogenic zone in surgical temporal lobe epilepsy patients. The proposition is that the resection volume in patients with favorable outcomes includes the epileptogenic zone. The association with the epileptogenic zone was assessed as follows: (1) how many of the interictal spike sources are within the resection volume in patients with favorable outcomes and (2) how many of the interictal spike sources are outside the resection volume in patients with unfavorable outcomes. Thirty-eight temporal lobe epilepsy (TLE) patients who underwent both ECoG monitoring and epilepsy surgery were recruited and their 10min of ECoG recordings were analyzed. Six tumor-related TLE patients were excluded in the analysis. Of the remaining 32 patients, 20 patients achieved favorable surgical outcomes (Engel I and II), while the surgical outcomes of 12 patients were unfavorable (Engel III and IV). In each patient, interictal spike sources were localized using sLORETA and co-registered into a reconstructed brain model. The correspondence rate with the resection volume was estimated by counting the percentage of interictal spike sources in the resection volume. The correspondence rate in patients with favorable outcomes was 72.8±22.1, which was significantly higher than that (41.2±28.8) of the patients with unfavorable outcomes (p=0.002). Nine out of twelve patients (75%) with unfavorable outcomes had multiple interictal spike source clusters both interior and exterior to the resection volume, while 4 of the 20 patients with favorable outcomes (20%) had such multiple clusters (p=0.021). In conclusion, interictal spike sources are highly associated with the epileptogenic zone. ECoG interictal spike source localization could help in the delineation of the potential resection volume.
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Affiliation(s)
- Changik Lee
- MEG Center, Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea; College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
| | - June Sic Kim
- MEG Center, Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea; Research Center for Sensory Organs, Seoul National University, Seoul, Republic of Korea.
| | - Woorim Jeong
- MEG Center, Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea; Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Science, Seoul, Republic of Korea.
| | - Chun Kee Chung
- MEG Center, Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea; Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Science, Seoul, Republic of Korea; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Republic of Korea.
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169
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Smith E, Duede S, Hanrahan S, Davis T, House P, Greger B. Seeing is believing: neural representations of visual stimuli in human auditory cortex correlate with illusory auditory perceptions. PLoS One 2013; 8:e73148. [PMID: 24023823 PMCID: PMC3762867 DOI: 10.1371/journal.pone.0073148] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 07/19/2013] [Indexed: 11/18/2022] Open
Abstract
In interpersonal communication, the listener can often see as well as hear the speaker. Visual stimuli can subtly change a listener's auditory perception, as in the McGurk illusion, in which perception of a phoneme's auditory identity is changed by a concurrent video of a mouth articulating a different phoneme. Studies have yet to link visual influences on the neural representation of language with subjective language perception. Here we show that vision influences the electrophysiological representation of phonemes in human auditory cortex prior to the presentation of the auditory stimulus. We used the McGurk effect to dissociate the subjective perception of phonemes from the auditory stimuli. With this paradigm we demonstrate that neural representations in auditory cortex are more closely correlated with the visual stimuli of mouth articulation, which drive the illusory subjective auditory perception, than the actual auditory stimuli. Additionally, information about visual and auditory stimuli transfer in the caudal-rostral direction along the superior temporal gyrus during phoneme perception as would be expected of visual information flowing from the occipital cortex into the ventral auditory processing stream. These results show that visual stimuli influence the neural representation in auditory cortex early in sensory processing and may override the subjective auditory perceptions normally generated by auditory stimuli. These findings depict a marked influence of vision on the neural processing of audition in tertiary auditory cortex and suggest a mechanistic underpinning for the McGurk effect.
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Affiliation(s)
- Elliot Smith
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Scott Duede
- Department of Linguistics, University of Utah, Salt Lake City, Utah, United States of America
| | - Sara Hanrahan
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Tyler Davis
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States of America
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah, United States of America
| | - Paul House
- Department of Neurosurgery, University of Utah, Salt Lake City, Utah, United States of America
| | - Bradley Greger
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, Utah, United States of America
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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170
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BOLD consistently matches electrophysiology in human sensorimotor cortex at increasing movement rates: a combined 7T fMRI and ECoG study on neurovascular coupling. J Cereb Blood Flow Metab 2013; 33:1448-56. [PMID: 23801242 PMCID: PMC3764395 DOI: 10.1038/jcbfm.2013.97] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 04/26/2013] [Accepted: 05/18/2013] [Indexed: 12/22/2022]
Abstract
Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is widely used to measure human brain function and relies on the assumption that hemodynamic changes mirror the underlying neuronal activity. However, an often reported saturation of the BOLD response at high movement rates has led to the notion of a mismatch in neurovascular coupling. We combined BOLD fMRI at 7T and intracranial electrocorticography (ECoG) to assess the relationship between BOLD and neuronal population activity in human sensorimotor cortex using a motor task with increasing movement rates. Though linear models failed to predict BOLD responses from the task, the measured BOLD and ECoG responses from the same tissue were in good agreement. Electrocorticography explained almost 80% of the mismatch between measured- and model-predicted BOLD responses, indicating that in human sensorimotor cortex, a large portion of the BOLD nonlinearity with respect to behavior (movement rate) is well predicted by electrophysiology. The results further suggest that other reported examples of BOLD mismatch may be related to neuronal processes, rather than to neurovascular uncoupling.
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171
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Human retrosplenial cortex displays transient theta phase locking with medial temporal cortex prior to activation during autobiographical memory retrieval. J Neurosci 2013; 33:10439-46. [PMID: 23785155 DOI: 10.1523/jneurosci.0513-13.2013] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The involvement of retrosplenial cortex (RSC) in human autobiographical memory retrieval has been confirmed by functional brain imaging studies, and is supported by anatomical evidence of strong connectivity between the RSC and memory structures within the medial temporal lobe (MTL). However, electrophysiological investigations of the RSC and its interaction with the MTL have mostly remained limited to the rodent brain. Recently, we reported a selective increase of high-frequency broadband (HFB; 70-180 Hz) power within the human RSC during autobiographical retrieval, and a predominance of 3-5 Hz theta band oscillations within the RSC during the resting state. In the current study, we aimed to explore the temporal dynamics of theta band interaction between human RSC and MTL during autobiographical retrieval. Toward this aim, we obtained simultaneous recordings from the RSC and MTL in human subjects undergoing invasive electrophysiological monitoring, and quantified the strength of RSC-MTL theta band phase locking. We observed significant phase locking in the 3-4 Hz theta range between the RSC and the MTL during autobiographical retrieval. This theta band phase coupling was transient and peaked at a consistent latency before the peak of RSC HFB power across subjects. Control analyses confirmed that theta phase coupling between the RSC and MTL was not seen for other conditions studied, other sites of recording, or other frequency ranges of interest (1-20 Hz). Our findings provide the first evidence of theta band interaction between the human RSC and MTL during conditions of autobiographical retrieval.
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172
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Roland JL, Hacker CD, Breshears JD, Gaona CM, Hogan RE, Burton H, Corbetta M, Leuthardt EC. Brain mapping in a patient with congenital blindness - a case for multimodal approaches. Front Hum Neurosci 2013; 7:431. [PMID: 23914170 PMCID: PMC3728570 DOI: 10.3389/fnhum.2013.00431] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/15/2013] [Indexed: 11/21/2022] Open
Abstract
Recent advances in basic neuroscience research across a wide range of methodologies have contributed significantly to our understanding of human cortical electrophysiology and functional brain imaging. Translation of this research into clinical neurosurgery has opened doors for advanced mapping of functionality that previously was prohibitively difficult, if not impossible. Here we present the case of a unique individual with congenital blindness and medically refractory epilepsy who underwent neurosurgical treatment of her seizures. Pre-operative evaluation presented the challenge of accurately and robustly mapping the cerebral cortex for an individual with a high probability of significant cortical re-organization. Additionally, a blind individual has unique priorities in one’s ability to read Braille by touch and sense the environment primarily by sound than the non-vision impaired person. For these reasons we employed additional measures to map sensory, motor, speech, language, and auditory perception by employing a number of cortical electrophysiologic mapping and functional magnetic resonance imaging methods. Our data show promising results in the application of these adjunctive methods in the pre-operative mapping of otherwise difficult to localize, and highly variable, functional cortical areas.
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Affiliation(s)
- Jarod L Roland
- Department of Neurological Surgery, Washington University School of Medicine , St. Louis, MO , USA
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173
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Hermes D, Miller KJ, Vansteensel MJ, Edwards E, Ferrier CH, Bleichner MG, van Rijen PC, Aarnoutse EJ, Ramsey NF. Cortical theta wanes for language. Neuroimage 2013; 85 Pt 2:738-48. [PMID: 23891904 DOI: 10.1016/j.neuroimage.2013.07.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 06/27/2013] [Accepted: 07/10/2013] [Indexed: 10/26/2022] Open
Abstract
The role of low frequency oscillations in language areas is not yet understood. Using ECoG in six human subjects, we studied whether different language regions show prominent power changes in a specific rhythm, in similar manner as the alpha rhythm shows the most prominent power changes in visual areas. Broca's area and temporal language areas were localized in individual subjects using fMRI. In these areas, the theta rhythm showed the most pronounced power changes and theta power decreased significantly during verb generation. To better understand the role of this language-related theta decrease, we then studied the interaction between low frequencies and local neuronal activity reflected in high frequencies. Amplitude-amplitude correlations showed that theta power correlated negatively with high frequency activity, specifically across verb generation trials. Phase-amplitude coupling showed that during control trials, high frequency power was coupled to theta phase, but this coupling decreased significantly during verb generation trials. These results suggest a dynamic interaction between the neuronal mechanisms underlying the theta rhythm and local neuronal activity in language areas. As visual areas show a pronounced alpha rhythm that may reflect pulsed inhibition, language regions show a pronounced theta rhythm with highly similar features.
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Affiliation(s)
- Dora Hermes
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Department of Neurology and Neurosurgery, Section Brain Function and Plasticity, Utrecht, The Netherlands; Department of Psychology, Stanford University, Stanford, USA
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174
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Bauer PR, Vansteensel MJ, Bleichner MG, Hermes D, Ferrier CH, Aarnoutse EJ, Ramsey NF. Mismatch Between Electrocortical Stimulation and Electrocorticography Frequency Mapping of Language. Brain Stimul 2013; 6:524-31. [DOI: 10.1016/j.brs.2013.01.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/06/2012] [Accepted: 01/02/2013] [Indexed: 11/28/2022] Open
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175
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Taimouri V, Akhondi-Asl A, Tomas-Fernandez X, Peters JM, Prabhu SP, Poduri A, Takeoka M, Loddenkemper T, Bergin AMR, Harini C, Madsen JR, Warfield SK. Electrode localization for planning surgical resection of the epileptogenic zone in pediatric epilepsy. Int J Comput Assist Radiol Surg 2013; 9:91-105. [PMID: 23793723 DOI: 10.1007/s11548-013-0915-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 06/10/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE In planning for a potentially curative resection of the epileptogenic zone in patients with pediatric epilepsy, invasive monitoring with intracranial EEG is often used to localize the seizure onset zone and eloquent cortex. A precise understanding of the location of subdural strip and grid electrodes on the brain surface, and of depth electrodes in the brain in relationship to eloquent areas is expected to facilitate pre-surgical planning. METHODS We developed a novel algorithm for the alignment of intracranial electrodes, extracted from post-operative CT, with pre-operative MRI. Our goal was to develop a method of achieving highly accurate localization of subdural and depth electrodes, in order to facilitate surgical planning. Specifically, we created a patient-specific 3D geometric model of the cortical surface from automatic segmentation of a pre-operative MRI, automatically segmented electrodes from post-operative CT, and projected each set of electrodes onto the brain surface after alignment of the CT to the MRI. Also, we produced critical visualization of anatomical landmarks, e.g., vasculature, gyri, sulci, lesions, or eloquent cortical areas, which enables the epilepsy surgery team to accurately estimate the distance between the electrodes and the anatomical landmarks, which might help for better assessment of risks and benefits of surgical resection. RESULTS Electrode localization accuracy was measured using knowledge of the position of placement from 2D intra-operative photographs in ten consecutive subjects who underwent intracranial EEG for pediatric epilepsy. Average spatial accuracy of localization was 1.31 ± 0.69 mm for all 385 visible electrodes in the photos. CONCLUSIONS In comparison with previously reported approaches, our algorithm is able to achieve more accurate alignment of strip and grid electrodes with minimal user input. Unlike manual alignment procedures, our algorithm achieves excellent alignment without time-consuming and difficult judgements from an operator.
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Abstract
Is there a distinct area within the human visual system that has a preferential response to numerals, as there is for faces, words, or scenes? We addressed this question using intracranial electrophysiological recordings and observed a significantly higher response in the high-frequency broadband range (high γ, 65-150 Hz) to visually presented numerals, compared with morphologically similar (i.e., letters and false fonts) or semantically and phonologically similar stimuli (i.e., number words and non-number words). Anatomically, this preferential response was consistently localized in the inferior temporal gyrus and anterior to the temporo-occipital incisure. This region lies within or close to the fMRI signal-dropout zone produced by the nearby auditory canal and venous sinus artifacts, an observation that may account for negative findings in previous fMRI studies of preferential response to numerals. Because visual numerals are culturally dependent symbols that are only learned through education, our novel finding of anatomically localized preferential response to such symbols provides a new example of acquired category-specific responses in the human visual system.
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177
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Johnson LA, Wander JD, Sarma D, Su DK, Fetz EE, Ojemann JG. Direct electrical stimulation of the somatosensory cortex in humans using electrocorticography electrodes: a qualitative and quantitative report. J Neural Eng 2013; 10:036021. [PMID: 23665776 DOI: 10.1088/1741-2560/10/3/036021] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Recently, electrocorticography-based brain-computer interfaces have been successfully used to translate cortical activity into control signals for external devices. However, the utility of such devices would be greatly enhanced by somatosensory feedback. Direct stimulation of somatosensory cortex evokes sensory perceptions, and is thus a promising option for closing the loop. Before this can be implemented in humans it is necessary to evaluate how changes in stimulus parameters are perceived and the extent to which they can be discriminated. APPROACH Electrical stimulation was delivered to the somatosensory cortex of human subjects implanted with electrocorticography grids. Subjects were asked to discriminate between stimuli of different frequency and amplitude as well as to report the qualitative sensations elicited by the stimulation. MAIN RESULTS In this study we show that in humans implanted with electrocorticography grids, variations in the amplitude or frequency of cortical electrical stimulation produce graded variations in percepts. Subjects were able to reliably distinguish between different stimuli. SIGNIFICANCE These results indicate that direct cortical stimulation is a feasible option for sensory feedback with brain-computer interface devices.
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Affiliation(s)
- L A Johnson
- Department of Neurological Surgery, The University of Washington, Seattle, WA 98195, USA.
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178
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Pieters TA, Conner CR, Tandon N. Recursive grid partitioning on a cortical surface model: an optimized technique for the localization of implanted subdural electrodes. J Neurosurg 2013; 118:1086-97. [DOI: 10.3171/2013.2.jns121450] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Precise localization of subdural electrodes (SDEs) is essential for the interpretation of data from intracranial electrocorticography recordings. Blood and fluid accumulation underneath the craniotomy flap leads to a nonlinear deformation of the brain surface and of the SDE array on postoperative CT scans and adversely impacts the accurate localization of electrodes located underneath the craniotomy. Older methods that localize electrodes based on their identification on a postimplantation CT scan with coregistration to a preimplantation MR image can result in significant problems with accuracy of the electrode localization. The authors report 3 novel methods that rely on the creation of a set of 3D mesh models to depict the pial surface and a smoothed pial envelope. Two of these new methods are designed to localize electrodes, and they are compared with 6 methods currently in use to determine their relative accuracy and reliability.
Methods
The first method involves manually localizing each electrode using digital photographs obtained at surgery. This is highly accurate, but requires time intensive, operator-dependent input. The second uses 4 electrodes localized manually in conjunction with an automated, recursive partitioning technique to localize the entire electrode array. The authors evaluated the accuracy of previously published methods by applying the methods to their data and comparing them against the photograph-based localization. Finally, the authors further enhanced the usability of these methods by using automatic parcellation techniques to assign anatomical labels to individual electrodes as well as by generating an inflated cortical surface model while still preserving electrode locations relative to the cortical anatomy.
Results
The recursive grid partitioning had the least error compared with older methods (672 electrodes, 6.4-mm maximum electrode error, 2.0-mm mean error, p < 10−18). The maximum errors derived using prior methods of localization ranged from 8.2 to 11.7 mm for an individual electrode, with mean errors ranging between 2.9 and 4.1 mm depending on the method used. The authors also noted a larger error in all methods that used CT scans alone to localize electrodes compared with those that used both postoperative CT and postoperative MRI. The large mean errors reported with these methods are liable to affect intermodal data comparisons (for example, with functional mapping techniques) and may impact surgical decision making.
Conclusions
The authors have presented several aspects of using new techniques to visualize electrodes implanted for localizing epilepsy. The ability to use automated labeling schemas to denote which gyrus a particular electrode overlies is potentially of great utility in planning resections and in corroborating the results of extraoperative stimulation mapping. Dilation of the pial mesh model provides, for the first time, a sense of the cortical surface not sampled by the electrode, and the potential roles this “electrophysiologically hidden” cortex may play in both eloquent function and seizure onset.
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Affiliation(s)
- Thomas A. Pieters
- 1Vivian L. Smith Department of Neurosurgery, University of Texas Health Science Center at Houston; and
| | - Christopher R. Conner
- 1Vivian L. Smith Department of Neurosurgery, University of Texas Health Science Center at Houston; and
| | - Nitin Tandon
- 1Vivian L. Smith Department of Neurosurgery, University of Texas Health Science Center at Houston; and
- 2Mischer Neuroscience Institute, Memorial Hermann Hospital-Texas Medical Center, Houston, Texas
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179
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Ojemann GA, Ojemann J, Ramsey NF. Relation between functional magnetic resonance imaging (fMRI) and single neuron, local field potential (LFP) and electrocorticography (ECoG) activity in human cortex. Front Hum Neurosci 2013; 7:34. [PMID: 23431088 PMCID: PMC3576621 DOI: 10.3389/fnhum.2013.00034] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 01/29/2013] [Indexed: 11/13/2022] Open
Abstract
The relation between changes in the blood oxygen dependent metabolic changes imaged by functional magnetic resonance imaging (fMRI) and neural events directly recorded from human cortex from single neurons, local field potentials (LFPs) and electrocorticogram (ECoG) is critically reviewed, based on the published literature including findings from the authors' laboratories. All these data are from special populations, usually patients with medically refractory epilepsy, as this provides the major opportunity for direct cortical neuronal recording in humans. For LFP and ECoG changes are often sought in different frequency bands, for single neurons in frequency of action potentials. Most fMRI studies address issues of functional localization. The relation of those findings to localized changes in neuronal recordings in humans has been established in several ways. Only a few studies have directly compared changes in activity from the same sites in the same individual, using the same behavioral measure. More often the comparison has been between fMRI and electrophysiologic changes in populations recorded from the same functional anatomic system as defined by lesion effects; in a few studies those systems have been defined by fMRI changes such as the "default" network. The fMRI-electrophysiologic relationships have been evaluated empirically by colocalization of significant changes, and by quantitative analyses, often multiple linear regression. There is some evidence that the fMRI-electrophysiology relationships differ in different cortical areas, particularly primary motor and sensory cortices compared to association cortex, but also within areas of association cortex. Although crucial for interpretation of fMRI changes as reflecting neural activity in human cortex, controversy remains as to these relationships. Supported by: Dutch Technology Foundation and University of Utrecht Grant UGT7685, ERC-Advanced grant 320708 (NR) and NIH grant NS065186 (JO).
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180
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Wang W, Collinger JL, Degenhart AD, Tyler-Kabara EC, Schwartz AB, Moran DW, Weber DJ, Wodlinger B, Vinjamuri RK, Ashmore RC, Kelly JW, Boninger ML. An electrocorticographic brain interface in an individual with tetraplegia. PLoS One 2013; 8:e55344. [PMID: 23405137 PMCID: PMC3566209 DOI: 10.1371/journal.pone.0055344] [Citation(s) in RCA: 212] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 12/27/2012] [Indexed: 11/19/2022] Open
Abstract
Brain-computer interface (BCI) technology aims to help individuals with disability to control assistive devices and reanimate paralyzed limbs. Our study investigated the feasibility of an electrocorticography (ECoG)-based BCI system in an individual with tetraplegia caused by C4 level spinal cord injury. ECoG signals were recorded with a high-density 32-electrode grid over the hand and arm area of the left sensorimotor cortex. The participant was able to voluntarily activate his sensorimotor cortex using attempted movements, with distinct cortical activity patterns for different segments of the upper limb. Using only brain activity, the participant achieved robust control of 3D cursor movement. The ECoG grid was explanted 28 days post-implantation with no adverse effect. This study demonstrates that ECoG signals recorded from the sensorimotor cortex can be used for real-time device control in paralyzed individuals.
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Affiliation(s)
- Wei Wang
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA, USA.
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181
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Esposito F, Singer N, Podlipsky I, Fried I, Hendler T, Goebel R. Cortex-based inter-subject analysis of iEEG and fMRI data sets: Application to sustained task-related BOLD and gamma responses. Neuroimage 2013; 66:457-68. [DOI: 10.1016/j.neuroimage.2012.10.080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 08/26/2012] [Accepted: 10/29/2012] [Indexed: 11/30/2022] Open
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182
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Chestek CA, Gilja V, Blabe CH, Foster BL, Shenoy KV, Parvizi J, Henderson JM. Hand posture classification using electrocorticography signals in the gamma band over human sensorimotor brain areas. J Neural Eng 2013; 10:026002. [PMID: 23369953 DOI: 10.1088/1741-2560/10/2/026002] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Brain-machine interface systems translate recorded neural signals into command signals for assistive technology. In individuals with upper limb amputation or cervical spinal cord injury, the restoration of a useful hand grasp could significantly improve daily function. We sought to determine if electrocorticographic (ECoG) signals contain sufficient information to select among multiple hand postures for a prosthetic hand, orthotic, or functional electrical stimulation system. APPROACH We recorded ECoG signals from subdural macro- and microelectrodes implanted in motor areas of three participants who were undergoing inpatient monitoring for diagnosis and treatment of intractable epilepsy. Participants performed five distinct isometric hand postures, as well as four distinct finger movements. Several control experiments were attempted in order to remove sensory information from the classification results. Online experiments were performed with two participants. MAIN RESULTS Classification rates were 68%, 84% and 81% for correct identification of 5 isometric hand postures offline. Using 3 potential controls for removing sensory signals, error rates were approximately doubled on average (2.1×). A similar increase in errors (2.6×) was noted when the participant was asked to make simultaneous wrist movements along with the hand postures. In online experiments, fist versus rest was successfully classified on 97% of trials; the classification output drove a prosthetic hand. Online classification performance for a larger number of hand postures remained above chance, but substantially below offline performance. In addition, the long integration windows used would preclude the use of decoded signals for control of a BCI system. SIGNIFICANCE These results suggest that ECoG is a plausible source of command signals for prosthetic grasp selection. Overall, avenues remain for improvement through better electrode designs and placement, better participant training, and characterization of non-stationarities such that ECoG could be a viable signal source for grasp control for amputees or individuals with paralysis.
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Affiliation(s)
- Cynthia A Chestek
- Stanford Institute for Neuroinnovation and Translational Neuroscience, W100-A, James H Clark Center, Stanford University, Stanford, CA 94305-5436, USA
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183
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Vansteensel MJ, Bleichner MG, Dintzner LT, Aarnoutse EJ, Leijten FSS, Hermes D, Ramsey NF. Task-free electrocorticography frequency mapping of the motor cortex. Clin Neurophysiol 2013; 124:1169-74. [PMID: 23340046 DOI: 10.1016/j.clinph.2012.08.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 07/03/2012] [Accepted: 08/30/2012] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Electrocortical stimulation mapping (ESM) is the current gold standard for functional mapping of the eloquent cortex prior to epilepsy surgery. The procedure is, however, time-consuming and quite demanding for patients. Electrocorticography frequency mapping (ECoG mapping) has been suggested as an adjunct method. Here, we investigated whether it is possible to perform mapping of motor regions using ECoG data of spontaneous movements. METHODS Using the video registration of seven epilepsy patients who underwent electrocorticography and ESM, we selected periods of spontaneous hand and arm movements and periods of rest. Frequency analysis was performed, and electrodes showing a significant change in power (4-7, 8-14, 15-25, 26-45 or 65-95 Hz) were compared with those being identified as relevant for hand and/or arm movement by ESM. RESULTS All frequency bands showed a high specificity (>0.80), and the 65-95 Hz frequency band additionally had a high sensitivity (0.82) for identifying ESM positive electrodes. CONCLUSIONS Our data show a good match between ECoG mapping of spontaneous movements and ESM data. SIGNIFICANCE The accurate match suggests that ECoG mapping of the motor cortex using spontaneous movements may be a valuable complement to ESM, especially when other options requiring patient cooperation fail.
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Affiliation(s)
- M J Vansteensel
- Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Department of Neurology and Neurosurgery, Section Brain Function and Plasticity, Utrecht, The Netherlands.
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184
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Abstract
Face-selective neural responses in the human fusiform gyrus have been widely examined. However, their causal role in human face perception is largely unknown. Here, we used a multimodal approach of electrocorticography (ECoG), high-resolution functional magnetic resonance imaging (fMRI), and electrical brain stimulation (EBS) to directly investigate the causal role of face-selective neural responses of the fusiform gyrus (FG) in face perception in a patient implanted with subdural electrodes in the right inferior temporal lobe. High-resolution fMRI identified two distinct FG face-selective regions [mFus-faces and pFus-faces (mid and posterior fusiform, respectively)]. ECoG revealed a striking anatomical and functional correspondence with fMRI data where a pair of face-selective electrodes, positioned 1 cm apart, overlapped mFus-faces and pFus-faces, respectively. Moreover, electrical charge delivered to this pair of electrodes induced a profound face-specific perceptual distortion during viewing of real faces. Specifically, the subject reported a "metamorphosed" appearance of faces of people in the room. Several controls illustrate the specificity of the effect to the perception of faces. EBS of mFus-faces and pFus-faces neither produced a significant deficit in naming pictures of famous faces on the computer, nor did it affect the appearance of nonface objects. Further, the appearance of faces remained unaffected during both sham stimulation and stimulation of a pair of nearby electrodes that were not face-selective. Overall, our findings reveal a striking convergence of fMRI, ECoG, and EBS, which together offer a rare causal link between functional subsets of the human FG network and face perception.
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185
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Ritaccio A, Beauchamp M, Bosman C, Brunner P, Chang E, Crone N, Gunduz A, Gupta D, Knight R, Leuthardt E, Litt B, Moran D, Ojemann J, Parvizi J, Ramsey N, Rieger J, Viventi J, Voytek B, Williams J, Schalk G. Proceedings of the Third International Workshop on Advances in Electrocorticography. Epilepsy Behav 2012; 25:605-13. [PMID: 23160096 PMCID: PMC4041796 DOI: 10.1016/j.yebeh.2012.09.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 09/08/2012] [Indexed: 10/27/2022]
Abstract
The Third International Workshop on Advances in Electrocorticography (ECoG) was convened in Washington, DC, on November 10-11, 2011. As in prior meetings, a true multidisciplinary fusion of clinicians, scientists, and engineers from many disciplines gathered to summarize contemporary experiences in brain surface recordings. The proceedings of this meeting serve as evidence of a very robust and transformative field but will yet again require revision to incorporate the advances that the following year will surely bring.
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Affiliation(s)
| | | | | | - Peter Brunner
- Albany Medical College, Albany, NY, USA, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Edward Chang
- University of California, San Francisco, CA, USA
| | - Nathan Crone
- Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Aysegul Gunduz
- Albany Medical College, Albany, NY, USA, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Disha Gupta
- Albany Medical College, Albany, NY, USA, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Robert Knight
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
| | | | - Brian Litt
- University of Pennsylvania, Pittsburgh, PA, USA
| | | | | | | | - Nick Ramsey
- University Medical Center, Utrecht University, Utrecht, The Netherlands
| | - Jochem Rieger
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA, University of Oldenburg, Oldenburg, Germany
| | | | | | | | - Gerwin Schalk
- Albany Medical College, Albany, NY, USA, Wadsworth Center, New York State Department of Health, Albany, NY, USA
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186
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Sleep spindles are locally modulated by training on a brain-computer interface. Proc Natl Acad Sci U S A 2012; 109:18583-8. [PMID: 23091013 DOI: 10.1073/pnas.1207532109] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The learning of a motor task is known to be improved by sleep, and sleep spindles are thought to facilitate this learning by enabling synaptic plasticity. In this study subjects implanted with electrocorticography (ECoG) arrays for long-term epilepsy monitoring were trained to control a cursor on a computer screen by modulating either the high-gamma or mu/beta power at a single electrode located over the motor or premotor area. In all trained subjects, spindle density in posttraining sleep was increased with respect to pretraining sleep in a remarkably spatially specific manner. The pattern of increased spindle activity reflects the functionally specific regions that were involved in learning of a highly novel and salient task during wakefulness, supporting the idea that sleep spindles are involved in learning to use a motor-based brain-computer interface device.
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187
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Harvey BM, Vansteensel MJ, Ferrier CH, Petridou N, Zuiderbaan W, Aarnoutse EJ, Bleichner MG, Dijkerman HC, van Zandvoort MJE, Leijten FSS, Ramsey NF, Dumoulin SO. Frequency specific spatial interactions in human electrocorticography: V1 alpha oscillations reflect surround suppression. Neuroimage 2012; 65:424-32. [PMID: 23085107 DOI: 10.1016/j.neuroimage.2012.10.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/10/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022] Open
Abstract
Electrical brain signals are often decomposed into frequency ranges that are implicated in different functions. Using subdural electrocorticography (ECoG, intracranial EEG) and functional magnetic resonance imaging (fMRI), we measured frequency spectra and BOLD responses in primary visual cortex (V1) and intraparietal sulcus (IPS). In V1 and IPS, 30-120 Hz (gamma, broadband) oscillations allowed population receptive field (pRF) reconstruction comparable to fMRI estimates. Lower frequencies, however, responded very differently in V1 and IPS. In V1, broadband activity extends down to 3 Hz. In the 4-7 Hz (theta) and 18-30 Hz (beta) ranges broadband activity increases power during stimulation within the pRF. However, V1 9-12 Hz (alpha) frequency oscillations showed a different time course. The broadband power here is exceeded by a frequency-specific power increase during stimulation of the area outside the pRF. As such, V1 alpha oscillations reflected surround suppression of the pRF, much like negative fMRI responses. They were consequently highly localized, depending on stimulus and pRF position, and independent between nearby electrodes. In IPS, all 3-25 Hz oscillations were strongest during baseline recording and correlated between nearby electrodes, consistent with large-scale disengagement. These findings demonstrate V1 alpha oscillations result from locally active functional processes and relate these alpha oscillations to negative fMRI signals. They highlight that similar oscillations in different areas reflect processes with different functional roles. However, both of these roles of alpha seem to reflect suppression of spiking activity.
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Affiliation(s)
- B M Harvey
- Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht 3584 CS, Netherlands.
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188
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Yang AI, Wang X, Doyle WK, Halgren E, Carlson C, Belcher TL, Cash SS, Devinsky O, Thesen T. Localization of dense intracranial electrode arrays using magnetic resonance imaging. Neuroimage 2012; 63:157-165. [PMID: 22759995 PMCID: PMC4408869 DOI: 10.1016/j.neuroimage.2012.06.039] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 06/17/2012] [Accepted: 06/20/2012] [Indexed: 10/28/2022] Open
Abstract
Intracranial electrode arrays are routinely used in the pre-surgical evaluation of patients with medically refractory epilepsy, and recordings from these electrodes have been increasingly employed in human cognitive neurophysiology due to their high spatial and temporal resolution. For both researchers and clinicians, it is critical to localize electrode positions relative to the subject-specific neuroanatomy. In many centers, a post-implantation MRI is utilized for electrode detection because of its higher sensitivity for surgical complications and the absence of radiation. However, magnetic susceptibility artifacts surrounding each electrode prohibit unambiguous detection of individual electrodes, especially those that are embedded within dense grid arrays. Here, we present an efficient method to accurately localize intracranial electrode arrays based on pre- and post-implantation MR images that incorporates array geometry and the individual's cortical surface. Electrodes are directly visualized relative to the underlying gyral anatomy of the reconstructed cortical surface of individual patients. Validation of this approach shows high spatial accuracy of the localized electrode positions (mean of 0.96 mm ± 0.81 mm for 271 electrodes across 8 patients). Minimal user input, short processing time, and utilization of radiation-free imaging are strong incentives to incorporate quantitatively accurate localization of intracranial electrode arrays with MRI for research and clinical purposes. Co-registration to a standard brain atlas further allows inter-subject comparisons and relation of intracranial EEG findings to the larger body of neuroimaging literature.
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Affiliation(s)
- Andrew I. Yang
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
| | - Xiuyuan Wang
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
| | - Werner K. Doyle
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
- Department of Neurosurgery, New York University School of Medicine, New York, NY 10016, USA
| | - Eric Halgren
- Department of Radiology, University of California at San Diego, San Diego, CA 92093, USA
- Department of Neurosciences, University of California at San Diego, San Diego, CA 92093, USA
- Department of Psychiatry, University of California at San Diego, San Diego, CA 92093, USA
| | - Chad Carlson
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
| | - Thomas L. Belcher
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
| | - Sydney S. Cash
- Department of Neurology, Epilepsy Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Orrin Devinsky
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
- Department of Neurosurgery, New York University School of Medicine, New York, NY 10016, USA
| | - Thomas Thesen
- Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA
- Department of Radiology, University of California at San Diego, San Diego, CA 92093, USA
- Department of Neurosciences, University of California at San Diego, San Diego, CA 92093, USA
- Department of Psychiatry, University of California at San Diego, San Diego, CA 92093, USA
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189
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Dissociation between neuronal activity in sensorimotor cortex and hand movement revealed as a function of movement rate. J Neurosci 2012; 32:9736-44. [PMID: 22787059 DOI: 10.1523/jneurosci.0357-12.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
It is often assumed that similar behavior is generated by the same brain activity. However, this does not take into account the brain state or recent behavioral history and movement initiation or continuation may not be similarly generated in the brain. To study whether similar movements are generated by the same brain activity, we measured neuronal population activity during repeated movements. Three human subjects performed a motor repetition task in which they moved their hand at four different rates (0.3, 0.5, 1, and 2 Hz). From high-resolution electrocorticography arrays implanted on motor and sensory cortex, high-frequency power (65-95 Hz) was extracted as a measure of neuronal population activity. During the two faster movement rates, high-frequency power was significantly suppressed, whereas movement parameters remained highly similar. This suppression was nonlinear: after the initial movement, neuronal population activity was reduced most strongly, and the data fit a model in which a fast decline rapidly converged to saturation. The amplitude of the beta-band suppression did not change with different rates. However, at the faster rates, beta power did not return to baseline between movements but remained suppressed. We take these findings to indicate that the extended beta suppression at the faster rates, which may suggest a release of inhibition in motor cortex, facilitates movement initiation. These results show that the relationship between behavior and neuronal activity is not consistent: recent movement influences the state of motor cortex and facilitates next movements by reducing the required level of neuronal activity.
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190
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Miller KJ, Hermes D, Honey CJ, Hebb AO, Ramsey NF, Knight RT, Ojemann JG, Fetz EE. Human motor cortical activity is selectively phase-entrained on underlying rhythms. PLoS Comput Biol 2012; 8:e1002655. [PMID: 22969416 PMCID: PMC3435268 DOI: 10.1371/journal.pcbi.1002655] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 07/05/2012] [Indexed: 11/18/2022] Open
Abstract
The functional significance of electrical rhythms in the mammalian brain remains uncertain. In the motor cortex, the 12-20 Hz beta rhythm is known to transiently decrease in amplitude during movement, and to be altered in many motor diseases. Here we show that the activity of neuronal populations is phase-coupled with the beta rhythm on rapid timescales, and describe how the strength of this relation changes with movement. To investigate the relationship of the beta rhythm to neuronal dynamics, we measured local cortical activity using arrays of subdural electrocorticographic (ECoG) electrodes in human patients performing simple movement tasks. In addition to rhythmic brain processes, ECoG potentials also reveal a spectrally broadband motif that reflects the aggregate neural population activity beneath each electrode. During movement, the amplitude of this broadband motif follows the dynamics of individual fingers, with somatotopically specific responses for different fingers at different sites on the pre-central gyrus. The 12-20 Hz beta rhythm, in contrast, is widespread as well as spatially coherent within sulcal boundaries and decreases in amplitude across the pre- and post-central gyri in a diffuse manner that is not finger-specific. We find that the amplitude of this broadband motif is entrained on the phase of the beta rhythm, as well as rhythms at other frequencies, in peri-central cortex during fixation. During finger movement, the beta phase-entrainment is diminished or eliminated. We suggest that the beta rhythm may be more than a resting rhythm, and that this entrainment may reflect a suppressive mechanism for actively gating motor function.
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Affiliation(s)
- Kai J. Miller
- Department of Neurosurgery, Stanford University, Stanford, California, United States of America
- Program in Neurobiology and Behavior, University of Washington, Seattle, Washington, United States of America
- Department of Physics, University of Washington, Seattle, Washington, United States of America
- * E-mail: (KJM); (EEF)
| | - Dora Hermes
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California, United States of America
- Section Brain Function and Plasticity, Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Christopher J. Honey
- Department of Psychology and Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Adam O. Hebb
- Department of Neurological Surgery, University of Washington, Seattle, Washington, United States of America
| | - Nick F. Ramsey
- Section Brain Function and Plasticity, Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Robert T. Knight
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California, United States of America
| | - Jeffrey G. Ojemann
- Department of Neurological Surgery, University of Washington, Seattle, Washington, United States of America
| | - Eberhard E. Fetz
- Program in Neurobiology and Behavior, University of Washington, Seattle, Washington, United States of America
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
- * E-mail: (KJM); (EEF)
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191
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Torres Valderrama A, Paclik P, Vansteensel MJ, Aarnoutse EJ, Ramsey NF. Error probability of intracranial brain computer interfaces under non-task elicited brain states. Clin Neurophysiol 2012; 123:2392-401. [PMID: 22695047 DOI: 10.1016/j.clinph.2012.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 05/04/2012] [Accepted: 05/06/2012] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Intracranial brain computer interfaces (BCIs) can be connected to the user's cortex permanently. The interfaces response when fed with non-task elicited brain activity becomes important as design criterion: ideally intracranial BCIs should remain silent. We study their error probability in the form of false alarms. METHODS Using electrocorticograms recorded during task and non-task brain states, we compute false alarms, investigate their origin and introduce strategies to reduce them, using signal detection theory, classifier cascading and adaptation concepts. RESULTS We show that the incessant dynamics of the brain is prone to spontaneously produce signals, the spectral and topographical characteristics of which can resemble those associated with common control tasks, generating brain state classification errors. CONCLUSIONS In addition to hit and bit rates, response of BCIs to non-task brain states constitutes an important measure of BCI performance. Static classification cascading reduces considerably false positives during no-task brain states. SIGNIFICANCE False alarms in intracranial BCIs are undesirable and could have dangerous consequences for the users. Designs which effectively incorporate the error correction strategies discussed in this paper, could be more successful when taken from the laboratory or acute care setting and used in the real world.
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192
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Rosenberg-Katz K, Jamshy S, Singer N, Podlipsky I, Kipervasser S, Andelman F, Neufeld MY, Intrator N, Fried I, Hendler T. Enhanced functional synchronization of medial and lateral PFC underlies internally-guided action planning. Front Hum Neurosci 2012; 6:79. [PMID: 22518101 PMCID: PMC3324921 DOI: 10.3389/fnhum.2012.00079] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Accepted: 03/21/2012] [Indexed: 11/15/2022] Open
Abstract
Actions are often internally guided, reflecting our covert will and intentions. The dorsomedial prefrontal cortex, including the pre-Supplementary Motor Area (pre-SMA), has been implicated in the internally generated aspects of action planning, such as choice and intention. Yet, the mechanism by which this area interacts with other cognitive brain regions such as the dorsolateral prefrontal cortex, a central node in decision-making, is still unclear. To shed light on this mechanism, brain activity was measured via fMRI and intracranial EEG in two studies during the performance of visually cued repeated finger tapping in which the choice of finger was guided by either a presented number (external) or self-choice (internal). A functional-MRI (fMRI) study in 15 healthy participants demonstrated that the pre-SMA, compared to the SMA proper, was more active and also more functionally correlated with the dorsolateral prefrontal cortex during internally compared to externally guided action planning (p < 0.05, random effect). In a similar manner, an intracranial-EEG study in five epilepsy patients showed greater inter-regional gamma-related connectivity between electrodes situated in medial and lateral aspects of the prefrontal cortex for internally compared to externally guided actions. Although this finding was observed for groups of electrodes situated both in the pre-SMA and SMA-proper, increased intra-cluster gamma-related connectivity was only observed for the pre-SMA (sign-test, p < 0.0001). Overall our findings provide multi-scale indications for the involvement of the dorsomedial prefrontal cortex, and especially the pre-SMA, in generating internally guided motor planning. Our intracranial-EEG results further point to enhanced functional connectivity between decision-making- and motor planning aspects of the PFC, as a possible neural mechanism for internally generated action planning.
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Affiliation(s)
- Keren Rosenberg-Katz
- Tel Aviv Sourasky Medical CenterFunctional Brain Imaging Unit, Israel
- Sackler School of Medicine, Tel-Aviv UniversityIsrael
| | - Shahar Jamshy
- Tel Aviv Sourasky Medical CenterFunctional Brain Imaging Unit, Israel
- School of Computer Science, Tel-Aviv UniversityIsrael
| | - Neomi Singer
- Tel Aviv Sourasky Medical CenterFunctional Brain Imaging Unit, Israel
- Department of Psychology, Tel-Aviv UniversityIsrael
| | - Ilana Podlipsky
- Tel Aviv Sourasky Medical CenterFunctional Brain Imaging Unit, Israel
| | - Svetlana Kipervasser
- EEG and Epilepsy Unit, Department of Neurology, Tel-Aviv Medical CenterIsrael
- Sackler School of Medicine, Tel-Aviv UniversityIsrael
| | - Fani Andelman
- Functional Neurosurgery Unit, Tel-Aviv Medical CenterIsrael
| | - Miri Y. Neufeld
- EEG and Epilepsy Unit, Department of Neurology, Tel-Aviv Medical CenterIsrael
- Sackler School of Medicine, Tel-Aviv UniversityIsrael
| | | | - Itzhak Fried
- Functional Neurosurgery Unit, Tel-Aviv Medical CenterIsrael
- Sackler School of Medicine, Tel-Aviv UniversityIsrael
- Department of Neurosurgery, David Geffen School of Medicine and Semel Institute for Neuroscience and Human Behavior, University of California, Los AngelesCA, USA
| | - Talma Hendler
- Tel Aviv Sourasky Medical CenterFunctional Brain Imaging Unit, Israel
- Sackler School of Medicine, Tel-Aviv UniversityIsrael
- Department of Psychology, Tel-Aviv UniversityIsrael
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193
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Dykstra AR, Chan AM, Quinn BT, Zepeda R, Keller CJ, Cormier J, Madsen JR, Eskandar EN, Cash SS. Individualized localization and cortical surface-based registration of intracranial electrodes. Neuroimage 2011; 59:3563-70. [PMID: 22155045 DOI: 10.1016/j.neuroimage.2011.11.046] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 10/17/2011] [Accepted: 11/16/2011] [Indexed: 11/13/2022] Open
Abstract
In addition to its widespread clinical use, the intracranial electroencephalogram (iEEG) is increasingly being employed as a tool to map the neural correlates of normal cognitive function as well as for developing neuroprosthetics. Despite recent advances, and unlike other established brain-mapping modalities (e.g. functional MRI, magneto- and electroencephalography), registering the iEEG with respect to neuroanatomy in individuals-and coregistering functional results across subjects-remains a significant challenge. Here we describe a method which coregisters high-resolution preoperative MRI with postoperative computerized tomography (CT) for the purpose of individualized functional mapping of both normal and pathological (e.g., interictal discharges and seizures) brain activity. Our method accurately (within 3mm, on average) localizes electrodes with respect to an individual's neuroanatomy. Furthermore, we outline a principled procedure for either volumetric or surface-based group analyses. We demonstrate our method in five patients with medically-intractable epilepsy undergoing invasive monitoring of the seizure focus prior to its surgical removal. The straight-forward application of this procedure to all types of intracranial electrodes, robustness to deformations in both skull and brain, and the ability to compare electrode locations across groups of patients makes this procedure an important tool for basic scientists as well as clinicians.
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Affiliation(s)
- Andrew R Dykstra
- Harvard-MIT Division of Health Sciences and Technology, Program in Speech and Hearing Bioscience and Technology, Cambridge, MA, USA.
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194
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Hermes D, Miller KJ, Vansteensel MJ, Aarnoutse EJ, Leijten FSS, Ramsey NF. Neurophysiologic correlates of fMRI in human motor cortex. Hum Brain Mapp 2011; 33:1689-99. [PMID: 21692146 DOI: 10.1002/hbm.21314] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 12/03/2010] [Accepted: 03/07/2011] [Indexed: 11/12/2022] Open
Abstract
The neurophysiological underpinnings of functional magnetic resonance imaging (fMRI) are not well understood. To understand the relationship between the fMRI blood oxygen level dependent (BOLD) signal and neurophysiology across large areas of cortex, we compared task related BOLD change during simple finger movement to brain surface electric potentials measured on a similar spatial scale using electrocorticography (ECoG). We found that spectral power increases in high frequencies (65-95 Hz), which have been related to local neuronal activity, colocalized with spatially focal BOLD peaks on primary sensorimotor areas. Independent of high frequencies, decreases in low frequency rhythms (<30 Hz), thought to reflect an aspect of cortical-subcortical interaction, colocalized with weaker BOLD signal increase. A spatial regression analysis showed that there was a direct correlation between the amplitude of the task induced BOLD change on different areas of primary sensorimotor cortex and the amplitude of the high frequency change. Low frequency change explained an additional, different part of the spatial BOLD variance. Together, these spectral power changes explained a significant 36% of the spatial variance in the BOLD signal change (R(2) = 0.36). These results suggest that BOLD signal change is largely induced by two separate neurophysiological mechanisms, one being spatially focal neuronal processing and the other spatially distributed low frequency rhythms.
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Affiliation(s)
- Dora Hermes
- Section Brain Function and Plasticity, Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
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195
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Bleichner MG, Vansteensel MJ, Huiskamp GM, Hermes D, Aarnoutse EJ, Ferrier CH, Ramsey NF. The effects of blood vessels on electrocorticography. J Neural Eng 2011; 8:044002. [PMID: 21654039 DOI: 10.1088/1741-2560/8/4/044002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrocorticography, primarily used in a clinical context, is becoming increasingly important for fundamental neuroscientific research, as well as for brain-computer interfaces. Recordings from these implanted electrodes have a number of advantages over non-invasive recordings in terms of band width, spatial resolution, smaller vulnerability to artifacts and overall signal quality. However, an unresolved issue is that signals vary greatly across electrodes. Here, we examine the effect of blood vessels lying between an electrode and the cortex on signals recorded from subdural grid electrodes. Blood vessels of different sizes cover extensive parts of the cortex causing variations in the electrode-cortex connection across grids. The power spectral density of electrodes located on the cortex and electrodes located on blood vessels obtained from eight epilepsy patients is compared. We find that blood vessels affect the power spectral density of the recorded signal in a frequency-band-specific way, in that frequencies between 30 and 70 Hz are attenuated the most. Here, the signal is attenuated on average by 30-40% compared to electrodes directly on the cortex. For lower frequencies this attenuation effect is less pronounced. We conclude that blood vessels influence the signal properties in a non-uniform manner.
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Affiliation(s)
- M G Bleichner
- Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, UMC Utrecht, Heidelberglaan 100, 3584 CS Utrecht, The Netherlands
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196
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Abstract
OBJECT Emerging research in evoked broadband electrocorticographic (ECoG) measurement from the cortical surface suggests that it might cleanly delineate the functional organization of cortex. The authors sought to demonstrate whether this could be done in a same-session, online manner to identify receptive and expressive language areas. METHODS The authors assessed the efficacy of simple integration of "χ-band" (76-200 Hz) change in the ECoG signal by implementing a simple band-pass filter to estimate broadband spectral change. Following a brief (less than 10-second) period to characterize baseline activity, χ-band activity was integrated while 7 epileptic patients with implanted ECoG electrodes performed a verb-generation task. RESULTS While the patients were performing verb-generation or noun-reading tasks, cortical activation was consistently identified in primary mouth motor area, superior temporal gyrus, and Broca and Wernicke association areas. Maps were robust after a mean time of 47 seconds (using an "activation overlap" measure). Correlation with electrocortical stimulation was not complete and was stronger for noun reading than verb generation. CONCLUSIONS Broadband ECoG changes can be captured online to identify eloquent cortex. This demonstrates the existence of a powerful new tool for functional mapping in the operative and chronic implant setting.
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197
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Hermes D, Vansteensel MJ, Albers AM, Bleichner MG, Benedictus MR, Mendez Orellana C, Aarnoutse EJ, Ramsey NF. Functional MRI-based identification of brain areas involved in motor imagery for implantable brain–computer interfaces. J Neural Eng 2011; 8:025007. [DOI: 10.1088/1741-2560/8/2/025007] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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198
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Probing brain connectivity by combined analysis of diffusion MRI tractography and electrocorticography. Comput Biol Med 2010; 41:1092-9. [PMID: 21129738 DOI: 10.1016/j.compbiomed.2010.11.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Revised: 11/11/2010] [Accepted: 11/11/2010] [Indexed: 11/20/2022]
Abstract
Electrocorticography (ECoG) allows for measurement of task-related local field potentials directly from cortex in neurosurgical patients. Diffusion tensor imaging (DTI) tractography is an MRI technique that allows for reconstruction of brain white matter tracts, which can be used to infer structural connectivity. This paper reports a novel merger of these two modalities. A processing stream is described in which fiber tracts near intracranial macroelectrodes showing task-related functional responses are isolated to explore structural networks related to working memory maintenance. Results show that ECoG-constrained tractography is useful for revealing structural connectivity patterns related to spatially- and temporally-specific functional responses.
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199
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Miller KJ, Hermes D, Honey CJ, Sharma M, Rao RPN, den Nijs M, Fetz EE, Sejnowski TJ, Hebb AO, Ojemann JG, Makeig S, Leuthardt EC. Dynamic modulation of local population activity by rhythm phase in human occipital cortex during a visual search task. Front Hum Neurosci 2010; 4:197. [PMID: 21119778 PMCID: PMC2990655 DOI: 10.3389/fnhum.2010.00197] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 09/29/2010] [Indexed: 12/22/2022] Open
Abstract
Brain rhythms are more than just passive phenomena in visual cortex. For the first time, we show that the physiology underlying brain rhythms actively suppresses and releases cortical areas on a second-to-second basis during visual processing. Furthermore, their influence is specific at the scale of individual gyri. We quantified the interaction between broadband spectral change and brain rhythms on a second-to-second basis in electrocorticographic (ECoG) measurement of brain surface potentials in five human subjects during a visual search task. Comparison of visual search epochs with a blank screen baseline revealed changes in the raw potential, the amplitude of rhythmic activity, and in the decoupled broadband spectral amplitude. We present new methods to characterize the intensity and preferred phase of coupling between broadband power and band-limited rhythms, and to estimate the magnitude of rhythm-to-broadband modulation on a trial-by-trial basis. These tools revealed numerous coupling motifs between the phase of low-frequency (δ, θ, α, β, and γ band) rhythms and the amplitude of broadband spectral change. In the θ and β ranges, the coupling of phase to broadband change is dynamic during visual processing, decreasing in some occipital areas and increasing in others, in a gyrally specific pattern. Finally, we demonstrate that the rhythms interact with one another across frequency ranges, and across cortical sites.
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Affiliation(s)
- Kai J Miller
- Neurobiology and Behavior, University of Washington Seattle, WA, USA
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200
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Kellis S, Miller K, Thomson K, Brown R, House P, Greger B. Decoding spoken words using local field potentials recorded from the cortical surface. J Neural Eng 2010; 7:056007. [PMID: 20811093 DOI: 10.1088/1741-2560/7/5/056007] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Pathological conditions such as amyotrophic lateral sclerosis or damage to the brainstem can leave patients severely paralyzed but fully aware, in a condition known as 'locked-in syndrome'. Communication in this state is often reduced to selecting individual letters or words by arduous residual movements. More intuitive and rapid communication may be restored by directly interfacing with language areas of the cerebral cortex. We used a grid of closely spaced, nonpenetrating micro-electrodes to record local field potentials (LFPs) from the surface of face motor cortex and Wernicke's area. From these LFPs we were successful in classifying a small set of words on a trial-by-trial basis at levels well above chance. We found that the pattern of electrodes with the highest accuracy changed for each word, which supports the idea that closely spaced micro-electrodes are capable of capturing neural signals from independent neural processing assemblies. These results further support using cortical surface potentials (electrocorticography) in brain-computer interfaces. These results also show that LFPs recorded from the cortical surface (micro-electrocorticography) of language areas can be used to classify speech-related cortical rhythms and potentially restore communication to locked-in patients.
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Affiliation(s)
- Spencer Kellis
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA
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