title: Soldiers With Posttraumatic Stress Disorder See a World Full of Threat: Magnetoencephalography Reveals Enhanced Tuning to Combat-Related Cues.
abstract: BACKGROUND
  Posttraumatic stress disorder (PTSD) is linked to elevated arousal and alterations in cognitive processes. Yet, whether a traumatic experience is linked to neural and behavioral differences in selective attentional tuning to traumatic stimuli is not known. The present study examined selective awareness of threat stimuli and underlying temporal-spatial patterns of brain activation associated with PTSD.
  
  
  METHODS
  Participants were 44 soldiers from the Canadian Armed Forces, 22 with PTSD and 22 without. All completed neuropsychological tests and clinical assessments. Magnetoencephalography data were collected while participants identified two targets in a rapidly presented stream of words. The first target was a number and the second target was either a combat-related or neutral word. The difference in accuracy for combat-related versus neutral words was used as a measure of attentional bias.
  
  
  RESULTS
  All soldiers showed a bias for combat-related words. This bias was enhanced in the PTSD group, and behavioral differences were associated with distinct patterns of brain activity. At early latencies, non-PTSD soldiers showed activation of midline frontal regions associated with fear regulation (90-340 ms after the second target presentation), whereas those with PTSD showed greater visual cortex activation linked to enhanced visual processing of trauma stimuli (200-300 ms).
  
  
  CONCLUSIONS
  These findings suggest that attentional biases in PTSD are linked to deficits in very rapid regulatory activation observed in healthy control subjects. Thus, sufferers with PTSD may literally see a world more populated by traumatic cues, contributing to a positive feedback loop that perpetuates the effects of trauma.
authors.affiliation: Department of Psychology, University of British Columbia, Vancouver, British Columbia. Electronic address: becket.todd@psych.ubc.ca.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Todd
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto.
authors.forename: Matt J
authors.initials: MJ
authors.lastname: MacDonald
authors.affiliation: Operational Stress Injury Clinic, The Royal Ottawa Mental Health Center, Ottawa; The Saint Lawrence Valley Correctional Treatment Center, Brockville.
authors.forename: Paul
authors.initials: P
authors.lastname: Sedge
authors.affiliation: Neurosciences and Mental Health Research Institute, Hospital for Sick Children, Toronto.
authors.forename: Amanda
authors.initials: A
authors.lastname: Robertson
authors.affiliation: Directorate of Mental Health, Canadian Forces Health Services, Ottawa.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Jetly
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto; Neurosciences and Mental Health Research Institute, Hospital for Sick Children, Toronto; Department of Medical Imaging, University of Toronto, Toronto; Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Margot J
authors.initials: MJ
authors.lastname: Taylor
authors.affiliation: Neurosciences and Mental Health Research Institute, Hospital for Sick Children, Toronto; Division of Neurology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Pang
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D003463:Cues; D004644:Emotions / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D008889:Military Personnel / Q000523:psychology*; D009483:Neuropsychological Tests; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology* / Q000523:psychology*; D000067453:War Exposure / Q000009:adverse effects*
keywords: Affect-biased attention; Attentional bias; Attentional blink; Beamforming; Magnetoencephalography (MEG); Posttraumatic stress disorder (PTSD); Soldiers