title: Decreased somatosensory activity to non-threatening touch in combat veterans with posttraumatic stress disorder.
abstract: Posttraumatic stress disorder (PTSD) is a severe psychiatric disorder prevalent in combat veterans. Previous neuroimaging studies have demonstrated that patients with PTSD exhibit abnormal responses to non-threatening visual and auditory stimuli, but have not examined somatosensory processing. Thirty male combat veterans, 16 with PTSD and 14 without, completed a tactile stimulation task during a 306-sensor magnetoencephalography (MEG) recording. Significant oscillatory neural responses were imaged using a beamforming approach. Participants also completed clinical assessments of PTSD, combat exposure, and depression. We found that veterans with PTSD exhibited significantly reduced activity during early (0-125 ms) tactile processing compared with combat controls. Specifically, veterans with PTSD had weaker activity in the left postcentral gyrus, left superior parietal area, and right prefrontal cortex in response to nonthreatening tactile stimulation relative to veterans without PTSD. The magnitude of activity in these brain regions was inversely correlated with symptom severity, indicating that those with the most severe PTSD had the most abnormal neural responses. Our findings are consistent with a resource allocation view of perceptual processing in PTSD, which directs attention away from nonthreatening sensory information.
authors.affiliation: Department of Psychology, Creighton University, Omaha, NE, USA. Electronic address: abadura@creighton.edu.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Badura-Brack
authors.affiliation: Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center (UNMC), Omaha, NE, USA; Center for Magnetoencephalography, UNMC, Omaha, NE, USA.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Becker
authors.affiliation: Department of Psychology, Creighton University, Omaha, NE, USA; Center for Magnetoencephalography, UNMC, Omaha, NE, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: McDermott
authors.affiliation: Department of Psychology, Creighton University, Omaha, NE, USA; Department of Psychology, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Tara J
authors.initials: TJ
authors.lastname: Ryan
authors.affiliation: Department of Psychology, Creighton University, Omaha, NE, USA.
authors.forename: Madelyn M
authors.initials: MM
authors.lastname: Becker
authors.affiliation: Department of Psychology, Creighton University, Omaha, NE, USA.
authors.forename: Allison R
authors.initials: AR
authors.lastname: Hearley
authors.affiliation: Center for Magnetoencephalography, UNMC, Omaha, NE, USA; Department of Psychology, University of Nebraska-Omaha, Omaha, NE, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Heinrichs-Graham
authors.affiliation: Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center (UNMC), Omaha, NE, USA; Center for Magnetoencephalography, UNMC, Omaha, NE, USA; Department of Psychology, University of Nebraska-Omaha, Omaha, NE, USA; Department of Neurological Sciences, UNMC, Omaha, NE, USA.
authors.forename: Tony W
authors.initials: TW
authors.lastname: Wilson
mesh_terms: D000328:Adult; D055826:Afghan Campaign 2001-; D001143:Arousal / Q000502:physiology*; D001288:Attention / Q000502:physiology; D001931:Brain Mapping; D006801:Humans; D054542:Iraq War, 2003-2011; D015225:Magnetoencephalography; D008297:Male; D010296:Parietal Lobe / Q000503:physiopathology*; D012016:Reference Values; D066191:Sensorimotor Cortex / Q000503:physiopathology*; D012684:Sensory Thresholds / Q000502:physiology*; D013223:Statistics as Topic; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology* / Q000523:psychology*; D014110:Touch / Q000502:physiology*; D014728:Veterans / Q000523:psychology*
keywords: MEG; Magnetoencephalography; Military; Oscillation; PTSD; Somatosensory; Tactile