J Psychiatry Neurosci 2016;41(4):251-260
Timothy J. McDermott, BA; Amy S. Badura-Brack, PhD; Katherine M. Becker, BS; Tara J. Ryan, BS; Maya M. Khanna, PhD; Elizabeth Heinrichs-Graham, PhD; Tony W. Wilson, PhD
Background: Posttraumatic stress disorder (PTSD) is associated with executive functioning deficits, including disruptions in working memory. In this study, we examined the neural dynamics of working memory processing in veterans with PTSD and a matched healthy control sample using magnetoencephalography (MEG).
Methods: Our sample of recent combat veterans with PTSD and demographically matched participants without PTSD completed a working memory task during a 306-sensor MEG recording. The MEG data were preprocessed and transformed into the time-frequency domain. Significant oscillatory brain responses were imaged using a beamforming approach to identify spatiotemporal dynamics.
Results: Fifty-one men were included in our analyses: 27 combat veterans with PTSD and 24 controls. Across all participants, a dynamic wave of neural activity spread from posterior visual cortices to left frontotemporal regions during encoding, consistent with a verbal working memory task, and was sustained throughout maintenance. Differences related to PTSD emerged during early encoding, with patients exhibiting stronger α oscillatory responses than controls in the right inferior frontal gyrus (IFG). Differences spread to the right supramarginal and temporal cortices during later encoding where, along with the right IFG, they persisted throughout the maintenance period.
Limitations: This study focused on men with combat-related PTSD using a verbal working memory task. Future studies should evaluate women and the impact of various traumatic experiences using diverse tasks.
Conclusion: Posttraumatic stress disorder is associated with neurophysiological abnormalities during working memory encoding and maintenance. Veterans with PTSD engaged a bilateral network, including the inferior prefrontal cortices and supramarginal gyri. Right hemispheric neural activity likely reflects compensatory processing, as veterans with PTSD work to maintain accurate performance despite known cognitive deficits associated with the disorder.
Submitted Feb. 25, 2015; Revised June 29, 2015; Accepted Aug. 26, 2015; Early-released Dec. 8, 2015
Affiliations: From the Department of Psychology, Creighton University, Omaha, NE, USA (McDermott, Badura-Brack, Ryan, Khanna); the Center for Magnetoencephalography, University of Nebraska Medical Center (UNMC), Omaha, NE, USA (McDermott, Becker, Heinrichs-Graham, Wilson); the Department of Psychology, Colorado State University, Fort Collins, CO, USA (Becker); the Department of Psychology, Simon Fraser University, Burnaby, BC, Canada (Ryan); the Department of Psychology, University of Nebraska-Omaha, Omaha, NE, USA (Heinrichs-Graham, Wilson); the Department of Pharmacology and Experimental Neuroscience, UNMC, Omaha, NE, USA (Wilson); and the Department of Neurological Sciences, UNMC, Omaha, NE, USA (Wilson).
Funding: This research was supported by a grant from the nonprofit organization At Ease, USA (A. Badura-Brack), by a Creighton University College of Arts and Science Summer Undergraduate Research Fellowship (T.J. McDermott), the Kinman-Oldfield Award from the University of Nebraska Foundation (T.W. Wilson), and grant R01-MH103220 from the National Institutes of Health (T.W. Wilson). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: None declared.
Contributors: T.J. McDermott, A. Badura-Brack, E. Heinrichs-Graham, T.J. Ryan, M.M. Khanna and T.W. Wilson designed the study. T.J. McDermott, A. Badura-Brack, E. Heinrichs-Graham, T.J. Ryan, and T.W. Wilson acquired the data, which T.J. McDermott, A. Badura-Brack, E. Heinrichs-Graham, K.M. Becker and T.W. Wilson analyzed. T.J. McDermott, A. Badura-Brack, E. Heinrichs-Graham and T.W. Wilson wrote the article, which all authors reviewed and approved for publication.
Correspondence to: A.S. Badura-Brack, Department of Psychology, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA; firstname.lastname@example.org