The Effects of PTSD on Functional Adaption in Visual Cortex

The goal of this project is to use functional magnetic resonance imaging (fMRI) to examine the effects of posttraumatic stress disorder (PTSD) on neural modulation in a high-level visual processing area. Two groups of subjects will be studied: combat-exposed veterans with PTSD and combat-exposed veterans without PTSD. Blood-oxygen level dependent (BOLD) will be measured while subjects view pictures with and without combat-related content in “repeated” and “different” (i.e., novel) presentation conditions. The pattern of BOLD response in the lateral occipital complex (LOC), a high-level visual processing area, will be examined. Specifically, we will compare habituation of the BOLD response in the LOC to repeated presentations of combat-related and non-combat-related pictures. We hypothesize that veterans with PTSD will show less habituation of the BOLD response in the LOC to repeated presentations of combat-related pictures than to repeated presentations of non-combat-related pictures. In addition, we will compare habituation of the BOLD response in the LOC in this novel fMRI task to habituation of the acoustic startle response, a well-established finding in individuals with PTSD. If reduced BOLD habituation in the visual cortex is truly a robust and reproducible finding in PTSD, then it may prove to be a useful biomarker for validating self-reported measures of PTSD and PTSD treatment efficacy.

PI: Linda L. Chao, Ph.D.
Funding Source: Department of Defense/NCIRE