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Laumann TO, Snyder AZ, Mitra A, Gordon EM, Gratton C, Adeyemo B, Gilmore AW, Nelson SM, Berg JJ, Greene DJ, McCarthy JE, Tagliazucchi E, Laufs H, Schlaggar BL, Dosenbach NUF, Petersen SE. On the Stability of BOLD fMRI Correlations. Cereb Cortex 2018; 27:4719-4732. [PMID: 27591147 DOI: 10.1093/cercor/bhw265] [Citation(s) in RCA: 253] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 08/02/2016] [Indexed: 12/26/2022] Open
Abstract
Measurement of correlations between brain regions (functional connectivity) using blood oxygen level dependent (BOLD) fMRI has proven to be a powerful tool for studying the functional organization of the brain. Recently, dynamic functional connectivity has emerged as a major topic in the resting-state BOLD fMRI literature. Here, using simulations and multiple sets of empirical observations, we confirm that imposed task states can alter the correlation structure of BOLD activity. However, we find that observations of "dynamic" BOLD correlations during the resting state are largely explained by sampling variability. Beyond sampling variability, the largest part of observed "dynamics" during rest is attributable to head motion. An additional component of dynamic variability during rest is attributable to fluctuating sleep state. Thus, aside from the preceding explanatory factors, a single correlation structure-as opposed to a sequence of distinct correlation structures-may adequately describe the resting state as measured by BOLD fMRI. These results suggest that resting-state BOLD correlations do not primarily reflect moment-to-moment changes in cognitive content. Rather, resting-state BOLD correlations may predominantly reflect processes concerned with the maintenance of the long-term stability of the brain's functional organization.
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Affiliation(s)
- Timothy O Laumann
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Abraham Z Snyder
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Anish Mitra
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Evan M Gordon
- VISN 17 Center of Excellence for Research on Returning War Veterans, Waco, TX 76711, USA.,Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, TX 75235, USA
| | - Caterina Gratton
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Babatunde Adeyemo
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Adrian W Gilmore
- Department of Psychological and Brain Sciences, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Steven M Nelson
- VISN 17 Center of Excellence for Research on Returning War Veterans, Waco, TX 76711, USA.,Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, TX 75235, USA
| | - Jeff J Berg
- Department of Psychological and Brain Sciences, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Deanna J Greene
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - John E McCarthy
- Department of Mathematics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Enzo Tagliazucchi
- Departmen of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Helmut Laufs
- Institute for Medical Psychology, Christian-Albrechts-Universitat zu Kiel, Kiel, Germany.,Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Bradley L Schlaggar
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Neurology, Brain Imaging Center, Goethe-Universitat Frankfurt am Main, Frankfurt, Germany.,Department of Neurology, Christian-Albrechts-Universitat zu Kiel, Kiel, Germany
| | - Nico U F Dosenbach
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Steven E Petersen
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Psychological and Brain Sciences, Washington University in St. Louis, St. Louis, MO 63110, USA.,Department of Neurology, Christian-Albrechts-Universitat zu Kiel, Kiel, Germany
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Jesunathadas M, Laitano J, Hamm TM, Santello M. Across-muscle coherence is modulated as a function of wrist posture during two-digit grasping. Neurosci Lett 2013; 553:68-71. [PMID: 23958501 DOI: 10.1016/j.neulet.2013.08.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 06/21/2013] [Accepted: 08/09/2013] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to investigate the extent to which correlated neural inputs, quantified as EMG-EMG coherence across intrinsic and extrinsic hand muscles, varied as a function of wrist angle during a constant force precision grip task. Eight adults (5 males; mean age 29 years) participated in the experiment. Subjects held an object using a two-digit precision grip at a constant force at a flexed, neutral, and extended wrist posture, while the EMG activity from intrinsic and extrinsic hand muscles was recorded through intramuscular fine-wire electrodes. The integral of z-transformed coherence computed across muscles pairs was greatest in the flexed wrist posture and significantly greater than EMG-EMG coherence measured in the neutral and extended wrist posture (P < 0.01 and 0.05, respectively). Furthermore, EMG-EMG coherence did not differ statistically between the extrinsic and intrinsic muscle pairs, even though it tended to be greater for the extrinsic muscle pair (P ≥ 0.063). These findings lend support to the notion of a functional role of correlated neural inputs to hand muscles for the task-dependent coordination of hand muscle activity that is likely mediated by somatosensory feedback.
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Affiliation(s)
- Mark Jesunathadas
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287-9709, United States
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Sakkalis V. Applied strategies towards EEG/MEG biomarker identification in clinical and cognitive research. Biomark Med 2011; 5:93-105. [PMID: 21319971 DOI: 10.2217/bmm.10.121] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
As the underlying causes of several neuronal disorders and neurodegenerative diseases still remain, to some extent, unknown and no accurate diagnostic tests are available, the identification of prognostic and predictive neurophysiological biomarkers has attracted tremendous interest. The continuous advancement of neuroscience methods applied in EEG and magnetoencephalography has been successful in capturing brain processes and identifying persistent cognitive deficits. In this article, the most promising approaches of this rapidly evolving field, along with some indicative clinical applications in major neuropathophysiological disorders, are reviewed. Such strategies for biomarker identification will lead the way to future clinical applications even if, currently, EEG biomarkers are in a premature state.
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Affiliation(s)
- Vangelis Sakkalis
- Institute of Computer Science, Foundation for Research & Technology, Science & Technology Park of Crete, Vassilika Vouton, Heraklion, Greece.
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Danna-Dos Santos A, Poston B, Jesunathadas M, Bobich LR, Hamm TM, Santello M. Influence of fatigue on hand muscle coordination and EMG-EMG coherence during three-digit grasping. J Neurophysiol 2010; 104:3576-87. [PMID: 20926609 DOI: 10.1152/jn.00583.2010] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fingertip force control requires fine coordination of multiple hand muscles within and across the digits. While the modulation of neural drive to hand muscles as a function of force has been extensively studied, much less is known about the effects of fatigue on the coordination of simultaneously active hand muscles. We asked eight subjects to perform a fatiguing contraction by gripping a manipulandum with thumb, index, and middle fingers while matching an isometric target force (40% maximal voluntary force) for as long as possible. The coordination of 12 hand muscles was quantified as electromyographic (EMG) muscle activation pattern (MAP) vector and EMG-EMG coherence. We hypothesized that muscle fatigue would cause uniform changes in EMG amplitude across all muscles and an increase in EMG-EMG coherence in the higher frequency bands but with an invariant heterogeneous distribution across muscles. Muscle fatigue caused a 12.5% drop in the maximum voluntary contraction force (P < 0.05) at task failure and an increase in the SD of force (P < 0.01). Although EMG amplitude of all muscles increased during the fatiguing contraction (P < 0.001), the MAP vector orientation did not change, indicating that a similar muscle coordination pattern was used throughout the fatiguing contraction. Last, EMG-EMG coherence (0-35 Hz) was significantly greater at the end than at the beginning of the fatiguing contraction (P < 0.01) but was heterogeneously distributed across hand muscles. These findings suggest that similar mechanisms are involved for modulating and sustaining digit forces in nonfatiguing and fatiguing contractions, respectively.
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Affiliation(s)
- Alessander Danna-Dos Santos
- School of Biological and Health Systems Engineering, 501 East Tyler Mall, Arizona State University, Tempe, AZ 85287-9709, USA
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Poston B, Danna-Dos Santos A, Jesunathadas M, Hamm TM, Santello M. Force-independent distribution of correlated neural inputs to hand muscles during three-digit grasping. J Neurophysiol 2010; 104:1141-54. [PMID: 20505123 DOI: 10.1152/jn.00185.2010] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ability to modulate digit forces during grasping relies on the coordination of multiple hand muscles. Because many muscles innervate each digit, the CNS can potentially choose from a large number of muscle coordination patterns to generate a given digit force. Studies of single-digit force production tasks have revealed that the electromyographic (EMG) activity scales uniformly across all muscles as a function of digit force. However, the extent to which this finding applies to the coordination of forces across multiple digits is unknown. We addressed this question by asking subjects (n = 8) to exert isometric forces using a three-digit grip (thumb, index, and middle fingers) that allowed for the quantification of hand muscle coordination within and across digits as a function of grasp force (5, 20, 40, 60, and 80% maximal voluntary force). We recorded EMG from 12 muscles (6 extrinsic and 6 intrinsic) of the three digits. Hand muscle coordination patterns were quantified in the amplitude and frequency domains (EMG-EMG coherence). EMG amplitude scaled uniformly across all hand muscles as a function of grasp force (muscle x force interaction: P = 0.997; cosines of angle between muscle activation pattern vector pairs: 0.897-0.997). Similarly, EMG-EMG coherence was not significantly affected by force (P = 0.324). However, coherence was stronger across extrinsic than that across intrinsic muscle pairs (P = 0.0039). These findings indicate that the distribution of neural drive to multiple hand muscles is force independent and may reflect the anatomical properties or functional roles of hand muscle groups.
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Affiliation(s)
- Brach Poston
- Department of Kinesiology, Arizona State University, Tempe, Arizona 85287-0404, USA
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