The neuroanatomic correlates of semantic memory deficits in patients with Gulf War illnesses: a pilot study

We used functional magnetic resonance imaging (fMRI) to study semantic memory processing in 38 Gulf War veterans in 3 affected groups (Syndromes 1, 2, and 3) and normal-deployed controls. Subjects were given the Semantic Object Retrieval Test (SORT), which requires participants to decide whether two features combine and result in the retrieval of a specific object (e.g., "desert" and "humps" → "camel"). Differences between groups were calculated using a repeated measures analysis of variance (ANOVA). Then, regions of interest were constructed and correlations assessed between the percent signal change (PSC) within these regions, followed by correlations between behavioral measures and PSC. We found affected groups performed less well on the SORT than the controls did, and behavioral differences were correlated to PSC within the caudate and thalamus. The combination of performance deficits and functional neuroimaging differences between affected Gulf War veterans and deployed normal controls begins to establish a neurobiological basis for their word-finding deficits.