title: Enhanced amygdala and medial prefrontal activation during nonconscious processing of fear in posttraumatic stress disorder: an fMRI study.
abstract: Biological models of posttraumatic stress disorder (PTSD) suggest that patients will display heightened amygdala but decreased medial prefrontal activity during processing of fear stimuli. However, a rapid and automatic alerting mechanism for responding to nonconscious signals of fear suggests that PTSD may display heightened rather than decreased MPFC under nonconscious processing of fear stimuli. This study used functional magnetic resonance imaging to examine blood oxygenation level-dependent signal changes during nonconscious presentation (16.7 ms, masked) of fearful and neutral faces in 15 participants with PTSD and 15 age and sex-matched healthy control participants. Results indicate that PTSD participants display increased amygdala and MPFC activity during nonconscious processing of fearful faces. These data extend existing models by suggesting that the impaired MPFC activation in PTSD may be limited to conscious fear processing. Hum Brain Mapp, 2008. (c) 2007 Wiley-Liss, Inc.
authors.affiliation: Brain Dynamics Centre, Westmead Hospital, Sydeny, New South Wales, Australia. r.bryant@unsw.edu.au
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bryant
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Kemp
authors.forename: Kim L
authors.initials: KL
authors.lastname: Felmingham
authors.forename: Belinda
authors.initials: B
authors.lastname: Liddell
authors.forename: Gloria
authors.initials: G
authors.lastname: Olivieri
authors.forename: Anthony
authors.initials: A
authors.lastname: Peduto
authors.forename: Evian
authors.initials: E
authors.lastname: Gordon
authors.forename: Leanne M
authors.initials: LM
authors.lastname: Williams
mesh_terms: D000328:Adult; D000679:Amygdala / Q000378:metabolism*; D005239:Fear / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D017397:Prefrontal Cortex / Q000378:metabolism*; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology*; D014473:Unconscious, Psychology