Neural correlates of associative learning and memory in veterans with posttraumatic stress disorder

Impaired attention and memory are symptoms frequently associated with posttraumatic stress disorder (PTSD). Although patients with PTSD frequently report memory difficulties and empirical research provides support for a memory deficit in PTSD, as of yet, no fMRI study has adequately investigated the neural correlates of learning and memory of neutral (i.e. not trauma related) material in patients with PTSD compared to controls. Twelve male veterans with PTSD, and twelve male veterans without PTSD, were recruited, and matched for age, region and year of deployment. Encoding and retrieval of 12 word-pair associates was assessed during fMRI in both experimental groups. Compared to controls veterans with PTSD revealed underactivation of the frontal cortex, and overactivation of the temporal cortex during the encoding phase. Retrieval of the paired associates resulted in underactivation of right frontal cortex, bilateral middle temporal gyri, and the left posterior hippocampus/parahippocampal gyrus in patients with PTSD. Deficits in memory performance in PTSD appear to be related to altered activity in fronto-temporal areas during both the encoding and retrieval phase of memory processing.