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MEG Working Memory N-Back Task Reveals Functional Deficits in Combat-Related Mild Traumatic Brain Injury

Huang, Ming-Xiong and Nichols, Sharon and Robb-Swan, Ashley and Angeles-Quinto, Annemarie and Harrington, Deborah L. and Drake, Angela and Huang, Charles W. and Song, Tao and Diwakar, Mithun and Risbrough, Victoria B. and Matthews, Scott and Clifford, Royce and Cheng, Chung-Kuan and Huang, Jeffrey W. and Sinha, Anusha and Yurgil, Kate A. and Ji, Zhengwei and Lerman, Imanuel and Lee, Roland R. and Baker, Dewleen G. (2019) MEG Working Memory N-Back Task Reveals Functional Deficits in Combat-Related Mild Traumatic Brain Injury. Cerebral Cortex, 29 (5). pp. 1953-1968. ISSN 1047-3211.

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Combat-related mild traumatic brain injury (mTBI) is a leading cause of sustained cognitive impairment in military service members and Veterans. However, the mechanism of persistent cognitive deficits including working memory (WM) dysfunction is not fully understood in mTBI. Few studies of WM deficits in mTBI have taken advantage of the temporal and frequency resolution afforded by electromagnetic measurements. Using magnetoencephalography (MEG) and an N-back WM task, we investigated functional abnormalities in combat-related mTBI. Study participants included 25 symptomatic active-duty service members or Veterans with combat-related mTBI and 20 healthy controls with similar combat experiences. MEG source–magnitude images were obtained for alpha (8–12 Hz), beta (15–30 Hz), gamma (30–90 Hz), and low-frequency (1–7 Hz) bands. Compared with healthy combat controls, mTBI participants showed increased MEG signals across frequency bands in frontal pole (FP), ventromedial prefrontal cortex, orbitofrontal cortex (OFC), and anterior dorsolateral prefrontal cortex (dlPFC), but decreased MEG signals in anterior cingulate cortex. Hyperactivations in FP, OFC, and anterior dlPFC were associated with slower reaction times. MEG activations in lateral FP also negatively correlated with performance on tests of letter sequencing, verbal fluency, and digit symbol coding. The profound hyperactivations from FP suggest that FP is particularly vulnerable to combat-related mTBI.

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Additional Information:© 2018 The Author(s). Published by Oxford University Press. Received: 09 November 2017; Revision Received: 11 March 2018; Accepted: 13 March 2018; Published: 13 April 2018. Funding: Supported in part by Merit Review Grants from the U.S. Department of Veterans Affairs to M.X. Huang (I01-CX000499, I01-RX001988, MHBA-010-14F, NURC-022-10F, NEUC-044-06S), R.R. Lee, D.L. Harrington (I01-CX000146), and The U.S. Naval Medical Research Center’s Advanced Medical Development program (Naval Medical Logistics Command Contract #N62645-11-C-4037, for MRS-II (D.G. Baker, M.A. Geyer, M.X. Huang, V.B. Risbrough). We acknowledge the MRS-II administrative core, Anjana Patel, Andrew De La Rosa, and members of the MRS-II Team, including logistic coordinators, clinician–interviewers, and data collection staff. We thank staff at the VA San Diego Healthcare System and the Veterans Medical Research Foundation (VRMF). We also thank the participating Marines and Veteran volunteers for their military service and participation in this study. Furthermore, we thank 3 anonymous reviewers for their constructive critiques and suggestions which substantially strengthened the paper. Conflict of interest: none declared.
Funding AgencyGrant Number
Department of Veterans AffairsI01-CX000499
Department of Veterans AffairsI01-RX001988
Department of Veterans AffairsMHBA-010-14F
Department of Veterans AffairsNURC-022-10F
Department of Veterans AffairsNEUC-044-06S
Department of Veterans AffairsI01-CX000146
Naval Medical Research CenterN62645-11-C-4037
Subject Keywords:blast brain injury, frontal pole, magnetoencephalography, traumatic brain injury, working memory
Issue or Number:5
Record Number:CaltechAUTHORS:20180423-101417454
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Official Citation:Ming-Xiong Huang, Sharon Nichols, Ashley Robb-Swan, Annemarie Angeles-Quinto, Deborah L Harrington, Angela Drake, Charles W Huang, Tao Song, Mithun Diwakar, Victoria B Risbrough, Scott Matthews, Royce Clifford, Chung-Kuan Cheng, Jeffrey W Huang, Anusha Sinha, Kate A Yurgil, Zhengwei Ji, Imanuel Lerman, Roland R Lee, Dewleen G Baker, MEG Working Memory N-Back Task Reveals Functional Deficits in Combat-Related Mild Traumatic Brain Injury, Cerebral Cortex, Volume 29, Issue 5, May 2019, Pages 1953–1968,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86006
Deposited By: Tony Diaz
Deposited On:25 Apr 2018 18:14
Last Modified:03 Oct 2019 19:38

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