Social cognition in patients following surgery to the prefrontal cortex

Impaired social cognition, including emotion recognition, may explain dysfunctional emotional and social behaviour in patients with lesions to the ventromedial prefrontal cortex (VMPFC). However, the VMPFC is a large, poorly defined area that can be sub-divided into orbital and medial sectors. We sought to investigate social cognition in patients with discrete, surgically circumscribed prefrontal lesions. Twenty-seven patients between 1 and 12 months post-neurosurgery were divided into groups based on Brodmann areas resected, determined by post-surgical magnetic resonance imaging. We hypothesised that patients with lesions to the VMPFC (n=5), anterior cingulate cortex (n=4), orbitofrontal cortex (n=7) and dorsolateral prefrontal cortex (DLPFC, n=11) would perform worse than a control group of 26 extra-cerebral neurosurgery patients on measures of dynamic facial emotion recognition, theory of mind (ToM) and empathy. Results indicated the VMPFC-lesioned group performed significantly worse than the control group on the facial emotion recognition task overall, and for fear specifically, and performed worse on the ToM measure. The DLPFC group also performed worse on the ToM and empathy measures, but DLPFC lesion location was not a predictor of performance in hierarchical multiple regressions that accounted for other variables, including the reduced estimated verbal IQ in this group. It was concluded that isolated orbital or medial prefrontal lesions are not sufficient to produce impairments in social cognition. This is the first study to demonstrate that it is the combination of lesions to both areas that affect social cognition, irrespective of lesion volume. While group sizes were similar to other comparable studies that included patients with discrete, surgically circumscribed lesions to the prefrontal cortex, future large, multi-site studies are needed to collect larger samples and confirm these results.