The right (nondominant) amygdala is crucial for processing facial emotion recognition (FER). Patients with temporal lobe epilepsy (TLE) associated with mesial temporal sclerosis (MTS) often incur right amygdalar damage, resulting in impaired FER if TLE onset occurs before age six. Consequently, early right mesiotemporal insult has been hypothesized to impair plasticity, resulting in FER deficits, whereas damage after age five results in no deficit. Using a uniformly seizure-free postsurgical population, we previously demonstrated that late-onset TLE does not predict FER deficits following surgery. This study was performed to examine whether early-onset TLE continues to impair FER following curative anteromedial temporal lobectomy (AMTL).
Controls (n=10) and early-onset patients (n=7) were recruited. All patients underwent nondominant AMTL, had TLE onset before age six, Wada-confirmed left-hemisphere language dominance, MTS on pre-operative MRI and biopsy, and were Engel class I five years postoperatively. Using a standardized (Ekman and Friesen) human face series, subjects were asked to match the affect of one of two faces to that of a simultaneously presented target face. Target faces expressed fear, anger, or happiness.
Statistical analysis (t-test) revealed significant FER impairment in the early-onset group (measured by percentage of faces correct) for fear (P=0.036), with FER for anger (P=0.571) and happiness (P=0.222) comparable to controls.
Despite seizure control/freedom post-AMTL, early TLE onset continues to impair FER for fear, but not anger or happiness. These results indicate that proper development of the right amygdala is necessary for optimal fear recognition, with other neural processes unable to compensate for early damage.