title: Parahippocampal activation evoked by masked traumatic images in posttraumatic stress disorder: a functional MRI study.
abstract: Posttraumatic stress disorder (PTSD) has been widely studied, but its neural mechanism is still unclear. The purpose of this study is to identify dysfunctional areas in PTSD throughout the whole brain to help to elucidate the neural mechanisms of PTSD. Sixteen patients with PTSD and sixteen healthy controls participated in this study. Traumatic images under perceptual threshold including scenes of earthquakes, traffic accidents, ambulances, emergency rooms, and crimes were presented to the participants, and brain activation was measured using functional MRI. Functional brain images of both groups were evaluated with random effect analysis for the whole brain. In the control group, activation in the ventral frontoparietal areas correlated significantly with presentation of the masked traumatic stimuli. In the PTSD group, activation was not observed in these areas, but significant activation correlated with the masked traumatic stimuli in the parahippocampal region including the left parahippocampal gyrus and tail of the left hippocampus. These results suggest that in PTSD patients activation in the ventral frontoparietal network associated with visual attention processing is attenuated, while the left hippocampal area associated with episodic and autobiographical memory is abnormally easily activated. This pattern of activation corresponds well to the clinical characteristics of PTSD, in which even slight traumatic stimuli tend to induce intrusive recollection or flashbacks, despite a general decrease in attention and ability to concentrate.
authors.affiliation: Department of Neuropsychiatry, University of Tokyo, Tokyo, Japan. saka-tky@umin.ac.jp
authors.forename: Hideshi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Rin
authors.initials: R
authors.lastname: Fukuda
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Okuaki
authors.forename: Mark
authors.initials: M
authors.lastname: Rogers
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
authors.forename: Toru
authors.initials: T
authors.lastname: Machida
authors.forename: Ichiro
authors.initials: I
authors.lastname: Shirouzu
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yamasue
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Akiyama
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Kato
mesh_terms: D000328:Adult; D000368:Aged; D017352:Echo-Planar Imaging; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D011569:Psychiatric Status Rating Scales; D013313:Stress Disorders, Post-Traumatic / Q000150:complications / Q000503:physiopathology* / Q000523:psychology
chemical_list: D010100:Oxygen