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Griggs WS, Norman SL, Tanter M, Liu C, Christopoulos V, Shapiro MG, Andersen RA. Functional ultrasound neuroimaging reveals mesoscopic organization of saccades in the lateral intraparietal area of posterior parietal cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.600796. [PMID: 39005362 PMCID: PMC11244887 DOI: 10.1101/2024.06.28.600796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
The lateral intraparietal cortex (LIP) located within the posterior parietal cortex (PPC) is an important area for the transformation of spatial information into accurate saccadic eye movements. Despite extensive research, we do not fully understand the functional anatomy of intended movement directions within LIP. This is in part due to technical challenges. Electrophysiology recordings can only record from small regions of the PPC, while fMRI and other whole-brain techniques lack sufficient spatiotemporal resolution. Here, we use functional ultrasound imaging (fUSI), an emerging technique with high sensitivity, large spatial coverage, and good spatial resolution, to determine how movement direction is encoded across PPC. We used fUSI to record local changes in cerebral blood volume in PPC as two monkeys performed memory-guided saccades to targets throughout their visual field. We then analyzed the distribution of preferred directional response fields within each coronal plane of PPC. Many subregions within LIP demonstrated strong directional tuning that was consistent across several months to years. These mesoscopic maps revealed a highly heterogenous organization within LIP with many small patches of neighboring cortex encoding different directions. LIP had a rough topography where anterior LIP represented more contralateral upward movements and posterior LIP represented more contralateral downward movements. These results address two fundamental gaps in our understanding of LIP's functional organization: the neighborhood organization of patches and the broader organization across LIP. These findings were achieved by tracking the same LIP populations across many months to years and developing mesoscopic maps of direction specificity previously unattainable with fMRI or electrophysiology methods.
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2
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Harper DE, Gopinath K, Smith JL, Gregory M, Ichesco E, Aronovich S, Harris RE, Harte SE, Clauw DJ, Fleischer CC. Characterization of visual processing in temporomandibular disorders using functional magnetic resonance imaging. Brain Behav 2023; 13:e2916. [PMID: 36793184 PMCID: PMC10013945 DOI: 10.1002/brb3.2916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 12/20/2022] [Accepted: 01/15/2023] [Indexed: 02/17/2023] Open
Abstract
BACKGROUND AND PURPOSE Many patients with chronic pain report hypersensitivity not only to noxious stimuli, but also to other modalities including innocuous touch, sound, and light, possibly due to differences in the processing of these stimuli. The goal of this study was to characterize functional connectivity (FC) differences between subjects with temporomandibular disorders (TMD) and pain-free controls during a visual functional magnetic resonance imaging (fMRI) task that included an unpleasant, strobing visual stimulus. We hypothesized the TMD cohort would exhibit maladaptations in brain networks consistent with multisensory hypersensitivities observed in TMD patients. METHODS This pilot study included 16 subjects, 10 with TMD and 6 pain-free controls. Clinical pain was characterized using self-reported questionnaires. Visual task-based fMRI data were collected on a 3T MR scanner and used to determine differences in FC via group independent component analysis. RESULTS Compared to controls, subjects with TMD exhibited abnormally increased FC between the default mode network and lateral prefrontal areas involved in attention and executive function, and impaired FC between the frontoparietal network and higher order visual processing areas. CONCLUSIONS The results indicate maladaptation of brain functional networks, likely due to deficits in multisensory integration, default mode network function, and visual attention and engendered by chronic pain mechanisms.
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Affiliation(s)
- Daniel E Harper
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, USA.,Chronic Pain and Fatigue Research Center, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Kaundinya Gopinath
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Jeremy L Smith
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Mia Gregory
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Eric Ichesco
- Chronic Pain and Fatigue Research Center, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sharon Aronovich
- Department of Oral and Maxillofacial Surgery and Hospital Dentistry, University of Michigan, Michigan Medicine, Ann Arbor, Michigan, USA
| | - Richard E Harris
- Chronic Pain and Fatigue Research Center, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Steven E Harte
- Chronic Pain and Fatigue Research Center, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Daniel J Clauw
- Chronic Pain and Fatigue Research Center, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Candace C Fleischer
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA.,Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, Georgia, USA
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Khalilzad Sharghi V, Maltbie EA, Pan WJ, Keilholz SD, Gopinath KS. Selective blockade of rat brain T-type calcium channels provides insights on neurophysiological basis of arousal dependent resting state functional magnetic resonance imaging signals. Front Neurosci 2022; 16:909999. [PMID: 36003960 PMCID: PMC9393715 DOI: 10.3389/fnins.2022.909999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/19/2022] [Indexed: 12/04/2022] Open
Abstract
A number of studies point to slow (0.1–2 Hz) brain rhythms as the basis for the resting-state functional magnetic resonance imaging (rsfMRI) signal. Slow waves exist in the absence of stimulation, propagate across the cortex, and are strongly modulated by vigilance similar to large portions of the rsfMRI signal. However, it is not clear if slow rhythms serve as the basis of all neural activity reflected in rsfMRI signals, or just the vigilance-dependent components. The rsfMRI data exhibit quasi-periodic patterns (QPPs) that appear to increase in strength with decreasing vigilance and propagate across the brain similar to slow rhythms. These QPPs can complicate the estimation of functional connectivity (FC) via rsfMRI, either by existing as unmodeled signal or by inducing additional wide-spread correlation between voxel-time courses of functionally connected brain regions. In this study, we examined the relationship between cortical slow rhythms and the rsfMRI signal, using a well-established pharmacological model of slow wave suppression. Suppression of cortical slow rhythms led to significant reduction in the amplitude of QPPs but increased rsfMRI measures of intrinsic FC in rats. The results suggest that cortical slow rhythms serve as the basis of only the vigilance-dependent components (e.g., QPPs) of rsfMRI signals. Further attenuation of these non-specific signals enhances delineation of brain functional networks.
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Affiliation(s)
- Vahid Khalilzad Sharghi
- Department of Biomedical Engineering, Emory University-Georgia Tech, Atlanta, GA, United States
| | - Eric A. Maltbie
- Department of Biomedical Engineering, Emory University-Georgia Tech, Atlanta, GA, United States
| | - Wen-Ju Pan
- Department of Biomedical Engineering, Emory University-Georgia Tech, Atlanta, GA, United States
| | - Shella D. Keilholz
- Department of Biomedical Engineering, Emory University-Georgia Tech, Atlanta, GA, United States
| | - Kaundinya S. Gopinath
- Department of Radiology & Imaging Sciences, Emory University, Atlanta, GA, United States
- *Correspondence: Kaundinya S. Gopinath,
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4
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Anteraper SA, Gopinath K, Hoch MJ, Waldrop-Valverde D, Franklin D, Letendre SL, Whitfield-Gabrieli S, Anderson AM. A comprehensive data-driven analysis framework for detecting impairments in brain function networks with resting state fMRI in HIV-infected individuals on cART. J Neurovirol 2021; 27:239-248. [PMID: 33666883 DOI: 10.1007/s13365-021-00943-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/14/2020] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
Central nervous system (CNS) sequelae continue to be common in HIV-infected individuals despite combination antiretroviral therapy (cART). These sequelae include HIV-associated neurocognitive disorder (HAND) and virologic persistence in the CNS. Resting state functional magnetic resonance imaging (rsfMRI) is a widely used tool to examine the integrity of brain function and pathology. In this study, we examined 16 HIV-positive (HIV+) subjects and 12 age, sex, and race matched HIV seronegative controls (HIV-) whole-brain high-resolution rsfMRI along with a battery of neurocognitive tests. A comprehensive data-driven analysis of rsfMRI revealed impaired functional connectivity, with very large effect sizes in executive function, language, and multisensory processing networks in HIV+ subjects. These results indicate the potential of high-resolution rsfMRI in combination with advanced data analysis techniques to yield biomarkers of neural impairment in HIV.
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Affiliation(s)
| | | | | | | | - Donald Franklin
- University of California At San Diego School of Medicine, La Jolla, San Diego, CA, USA
| | - Scott L Letendre
- University of California At San Diego School of Medicine, La Jolla, San Diego, CA, USA
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Weldon KB, Olman CA. Forging a path to mesoscopic imaging success with ultra-high field functional magnetic resonance imaging. Philos Trans R Soc Lond B Biol Sci 2020; 376:20200040. [PMID: 33190599 PMCID: PMC7741029 DOI: 10.1098/rstb.2020.0040] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) studies with ultra-high field (UHF, 7+ Tesla) technology enable the acquisition of high-resolution images. In this work, we discuss recent achievements in UHF fMRI at the mesoscopic scale, on the order of cortical columns and layers, and examine approaches to addressing common challenges. As researchers push to smaller and smaller voxel sizes, acquisition and analysis decisions have greater potential to degrade spatial accuracy, and UHF fMRI data must be carefully interpreted. We consider the impact of acquisition decisions on the spatial specificity of the MR signal with a representative dataset with 0.8 mm isotropic resolution. We illustrate the trade-offs in contrast with noise ratio and spatial specificity of different acquisition techniques and show that acquisition blurring can increase the effective voxel size by as much as 50% in some dimensions. We further describe how different sources of degradations to spatial resolution in functional data may be characterized. Finally, we emphasize that progress in UHF fMRI depends not only on scientific discovery and technical advancement, but also on informal discussions and documentation of challenges researchers face and overcome in pursuit of their goals. This article is part of the theme issue 'Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity'.
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Affiliation(s)
- Kimberly B Weldon
- Department of Psychiatry and Behavioral Sciences, University of Minnesota, Minneapolis, MN 55455, USA.,Center for Magnetic Resonance Imaging, University of Minnesota, Minneapolis, MN 55455, USA
| | - Cheryl A Olman
- Center for Magnetic Resonance Imaging, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Psychology, University of Minnesota, Minneapolis, MN 55455, USA
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Examining fMRI time-series entropy as a marker for brain E/I balance with pharmacological neuromodulation in a non-human primate translational model. Neurosci Lett 2020; 728:134984. [PMID: 32315710 DOI: 10.1016/j.neulet.2020.134984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 04/02/2020] [Accepted: 04/13/2020] [Indexed: 11/23/2022]
Abstract
Recently, there has been a lot of interest in the neuroimaging community in exploring fMRI time-series measures of local neuronal activity and excitation/inhibition (E/I) balance in the brain. In this preliminary study we probed the sensitivity of widely used sample entropy (SE) measure at multiple scales to controlled alteration of the brain's E/I balance in non-human primates (NHPs) with a well-characterized sub-anesthetic ketamine infusion fMRI model. We found that SE failed to detect the expected changes in E/I balance induced by ketamine. Subsequently, noticing that the complexity in the time series contributing SE could be dominated by non-neuronal noise in this experimental setting, we developed a new time-series measure called restricted sample entropy (RSE) by restricting SE estimations to regular portions of the fMRI time-series. RSE was able to adequately reflect the increased excitatory activity engendered by disinhibition of glutamergic neurons, through sub-anesthetic ketamine infusion. These results show that RSE is potentially a powerful tool for examining local neural activity, E/I balance, and alterations in brain state.
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7
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Krishnamurthy LC, Krishnamurthy V, Crosson B, Rothman DL, Schwam DM, Greenberg D, Pugh KR, Morris RD. Strength of resting state functional connectivity and local GABA concentrations predict oral reading of real and pseudo-words. Sci Rep 2019; 9:11385. [PMID: 31388067 PMCID: PMC6684813 DOI: 10.1038/s41598-019-47889-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 07/24/2019] [Indexed: 02/06/2023] Open
Abstract
Reading is a learned activity that engages multiple cognitive systems. In a cohort of typical and struggling adult readers we show evidence that successful oral reading of real words is related to gamma-amino-butyric acid (GABA) concentration in the higher-order language system, whereas reading of unfamiliar pseudo-words is not related to GABA in this system. We also demonstrate the capability of resting state functional connectivity (rsFC) combined with GABA measures to predict single real word compared to pseudo-word reading performance. Results show that the strength of rsFC between left fusiform gyrus (L-FG) and higher-order language systems predicts oral reading behavior of real words, irrespective of the local concentration of GABA. On the other hand, pseudo-words, which require grapheme-to-phoneme conversion, are not predicted by the connection between L-FG and higher-order language system. This suggests that L-FG may have a multi-functional role: lexical processing of real words and grapheme-to-phoneme processing of pseudo-words. Additionally, rsFC between L-FG, pre-motor, and putamen areas are positively related to the oral reading of both real and pseudo-words, suggesting that text may be converted into a phoneme sequence for speech initiation and production regardless of whether the stimulus is a real word or pseudo-word. In summary, from a systems neuroscience perspective, we show that: (i) strong rsFC between higher order visual, language, and pre-motor areas can predict and differentiate efficient oral reading of real and pseudo-words. (ii) GABA measures, along with rsFC, help to further differentiate the neural pathways for previously learned real words versus unfamiliar pseudo-words.
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Affiliation(s)
- Lisa C Krishnamurthy
- Department of Physics & Astronomy, Georgia State University, Atlanta, GA, 30303, United States.
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, 30033, United States.
- Center for Advanced Brain Imaging, Georgia State University and Georgia Institute of Technology, Atlanta, GA, 30318, United States.
| | - Venkatagiri Krishnamurthy
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, 30033, United States
- Center for Advanced Brain Imaging, Georgia State University and Georgia Institute of Technology, Atlanta, GA, 30318, United States
- Department of Neurology, Emory University, Atlanta, GA, 30322, United States
| | - Bruce Crosson
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VAMC, Decatur, GA, 30033, United States
- Center for Advanced Brain Imaging, Georgia State University and Georgia Institute of Technology, Atlanta, GA, 30318, United States
- Department of Neurology, Emory University, Atlanta, GA, 30322, United States
- Department of Psychology, Georgia State University, Atlanta, GA, 30303, United States
| | - Douglas L Rothman
- Departments of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, 06520, United States
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT, 06520, United States
| | - Dina M Schwam
- Department of Learning Sciences, Georgia State University, Atlanta, GA, 30303, United States
- Department of Psychology and Human Services, Mercer University, Macon, GA, United States
| | - Daphne Greenberg
- Department of Learning Sciences, Georgia State University, Atlanta, GA, 30303, United States
| | - Kenneth R Pugh
- Departments of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, 06520, United States
- Haskins Laboratories, New Haven, CT, United States
- Department of Psychological Sciences, University of Connecticut, Storrs, CT, United States
| | - Robin D Morris
- Center for Advanced Brain Imaging, Georgia State University and Georgia Institute of Technology, Atlanta, GA, 30318, United States
- Department of Psychology, Georgia State University, Atlanta, GA, 30303, United States
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8
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Drucker JH, Sathian K, Crosson B, Krishnamurthy V, McGregor KM, Bozzorg A, Gopinath K, Krishnamurthy LC, Wolf SL, Hart AR, Evatt M, Corcos DM, Hackney ME. Internally Guided Lower Limb Movement Recruits Compensatory Cerebellar Activity in People With Parkinson's Disease. Front Neurol 2019; 10:537. [PMID: 31231297 PMCID: PMC6566131 DOI: 10.3389/fneur.2019.00537] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 05/03/2019] [Indexed: 11/14/2022] Open
Abstract
Background: Externally guided (EG) and internally guided (IG) movements are postulated to recruit two parallel neural circuits, in which motor cortical neurons interact with either the cerebellum or striatum via distinct thalamic nuclei. Research suggests EG movements rely more heavily on the cerebello-thalamo-cortical circuit, whereas IG movements rely more on the striato-pallido-thalamo-cortical circuit (1). Because Parkinson's (PD) involves striatal dysfunction, individuals with PD have difficulty generating IG movements (2). Objectives: Determine whether individuals with PD would employ a compensatory mechanism favoring the cerebellum over the striatum during IG lower limb movements. Methods: 22 older adults with mild-moderate PD, who had abstained at least 12 h from anti-PD medications, and 19 age-matched controls performed EG and IG rhythmic foot-tapping during functional magnetic resonance imaging. Participants with PD tapped with their right (more affected) foot. External guidance was paced by a researcher tapping participants' ipsilateral 3rd metacarpal in a pattern with 0.5 to 1 s intervals, while internal guidance was based on pre-scan training in the same pattern. BOLD activation was compared between tasks (EG vs. IG) and groups (PD vs. control). Results: Both groups recruited the putamen and cerebellar regions. The PD group demonstrated less activation in the striatum and motor cortex than controls. A task (EG vs. IG) by group (PD vs. control) interaction was observed in the cerebellum with increased activation for the IG condition in the PD group. Conclusions: These findings support the hypothesized compensatory shift in which the dysfunctional striatum is assisted by the less affected cerebellum to accomplish IG lower limb movement in individuals with mild-moderate PD. These findings are of relevance for temporal gait dysfunction and freezing of gait problems frequently noted in many people with PD and may have implications for future therapeutic application.
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Affiliation(s)
- Jonathan H Drucker
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Department of Neurology, School of Medicine, Emory University, Atlanta, GA, United States
| | - K Sathian
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Department of Neurology, School of Medicine, Emory University, Atlanta, GA, United States.,Departments of Neurology, Neural and Behavioral Sciences, and Psychology, Pennsylvania State University, Hershey, PA, United States
| | - Bruce Crosson
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Department of Neurology, School of Medicine, Emory University, Atlanta, GA, United States.,Department of Psychology, Georgia State University, Atlanta, GA, United States.,Health and Rehabilitation Science, University of Queensland, Brisbane, QLD, Australia
| | - Venkatagiri Krishnamurthy
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Department of Neurology, School of Medicine, Emory University, Atlanta, GA, United States
| | - Keith M McGregor
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Department of Neurology, School of Medicine, Emory University, Atlanta, GA, United States
| | - Ariyana Bozzorg
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States
| | - Kaundinya Gopinath
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States
| | - Lisa C Krishnamurthy
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Department of Physics and Astronomy, Georgia State University, Atlanta, GA, United States
| | - Steven L Wolf
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Division of Physical Therapy, Department of Rehabilitation Medicine, School of Medicine, Emory University, Atlanta, GA, United States.,Department of Cell Biology, School of Medicine, Emory University, Atlanta, GA, United States.,Division of General Medicine and Geriatrics, Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
| | - Ariel R Hart
- Division of General Medicine and Geriatrics, Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
| | - Marian Evatt
- Department of Neurology, School of Medicine, Emory University, Atlanta, GA, United States
| | - Daniel M Corcos
- Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States
| | - Madeleine E Hackney
- Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, United States.,Division of Physical Therapy, Department of Rehabilitation Medicine, School of Medicine, Emory University, Atlanta, GA, United States.,Division of General Medicine and Geriatrics, Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
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9
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Eklund A, Knutsson H, Nichols TE. Cluster failure revisited: Impact of first level design and physiological noise on cluster false positive rates. Hum Brain Mapp 2019; 40:2017-2032. [PMID: 30318709 PMCID: PMC6445744 DOI: 10.1002/hbm.24350] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 07/30/2018] [Accepted: 08/01/2018] [Indexed: 01/16/2023] Open
Abstract
Methodological research rarely generates a broad interest, yet our work on the validity of cluster inference methods for functional magnetic resonance imaging (fMRI) created intense discussion on both the minutia of our approach and its implications for the discipline. In the present work, we take on various critiques of our work and further explore the limitations of our original work. We address issues about the particular event-related designs we used, considering multiple event types and randomization of events between subjects. We consider the lack of validity found with one-sample permutation (sign flipping) tests, investigating a number of approaches to improve the false positive control of this widely used procedure. We found that the combination of a two-sided test and cleaning the data using ICA FIX resulted in nominal false positive rates for all data sets, meaning that data cleaning is not only important for resting state fMRI, but also for task fMRI. Finally, we discuss the implications of our work on the fMRI literature as a whole, estimating that at least 10% of the fMRI studies have used the most problematic cluster inference method (p = .01 cluster defining threshold), and how individual studies can be interpreted in light of our findings. These additional results underscore our original conclusions, on the importance of data sharing and thorough evaluation of statistical methods on realistic null data.
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Affiliation(s)
- Anders Eklund
- Division of Medical Informatics, Department of Biomedical EngineeringLinköping UniversityLinköpingSweden
- Division of Statistics & Machine Learning, Department of Computer and Information ScienceLinköping UniversityLinköpingSweden
- Center for Medical Image Science and Visualization (CMIV)Linköping UniversityLinköpingSweden
| | - Hans Knutsson
- Division of Medical Informatics, Department of Biomedical EngineeringLinköping UniversityLinköpingSweden
- Center for Medical Image Science and Visualization (CMIV)Linköping UniversityLinköpingSweden
| | - Thomas E. Nichols
- Big Data InstituteUniversity of OxfordOxfordUnited Kingdom
- Wellcome Trust Centre for Integrative Neuroimaging (WIN‐FMRIB)University of OxfordOxfordUnited Kingdom
- Department of StatisticsUniversity of WarwickCoventryUnited Kingdom
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