| This thesis explored mechanisms underlying the perception, encoding, and maintenance of social cues in working memory. A series of three experiments investigated the role of medial temporal lobe (MTL) structures, the orbitofrontal cortex (OFC), and ventral extrastriate visual regions in working memory for facial expressions using a combination of delayed match-to-sample (DMS) tasks and functional magnetic resonance imaging (fMRI) in healthy young adults.;The first experiment examined transient versus sustained fMRI activity when subjects were instructed to maintain either the expression or identity of a face. This experiment demonstrated that expression and identity information are bound together and maintained by the OFC, hippocampus, and amygdala across a delay period. However, expression and identity are transiently processed separately in superior temporal sulcus and inferior temporal gyrus, respectively. These results support the hypothesis that the MTL and OFC are critical for flexibly binding together information in working memory.;The second experiment examined fMRI activity underlying disambiguation, the separation of memory representations with overlapping features, during working memory when subjects maintained multiple emotional expressions. This experiment demonstrated that the OFC and hippocampus are involved in the disambiguation of overlapping face representations during encoding and maintenance, respectively. These results support a role for the OFC and MTL in distinguishing between social cues with overlapping features and maintaining these distinctions in working memory.;The third experiment examined the effects of face familiarity on the disambiguation of overlapping face representations in working memory. This experiment demonstrated no benefit of newly acquired familiarity on the DMS task, however, subjects' ability to discriminate between familiar and novel faces did correlate with DMS task performance. These results indicate that recognition of faces as familiar or novel may aid in disambiguating overlapping face representations.;In conclusion, these experiments demonstrate a role for the OFC and MTL in the circuitry underlying social interactions, specifically for the active maintenance of social cues in working memory. OFC and MTL structures work in conjunction with extrastriate visual regions to accurately identify, monitor, and disambiguate face representations in order to guide appropriate social behaviors. |
