Abstracts

RATIONALE: A strong relationship exists between emotion, episodic memory, and temporal lobe structures. Previous studies of emotional memory in patients with temporal lobe epilepsy (TLE) have typically involved word lists and stories that may lack strong personal or motivational significance. In contrast, autobiographical memories are specific events that an individual has experienced and thus may have more intrinsic emotional significance. The purpose of the present study was to examine whether emotional autobiographic memories would be influenced by the extent of amygdalar/hippocampal volume asymmetries in patients with nonlesional TLE and to examine the relationship between mood and emotional memory.
METHODS: Patients with nonlesional TLE (12 Right, 12 Left) and Controls were given a Crovitz task to elicit recall of personal memories that were associated with specific emotions (fear, anger, joy, happiness). Memories were rated on a 1-100 scale by blinded raters according to valence and content. The TLE subjects were left language dominant, based on Wada, and had unilateral EEG foci. The TLE groups did not differ in age, education, or seizure related variables. Hippocampal and amygdala volumes were quantitatively measured in a blinded fashion, from volumetrically acquired MRI, and corrected for total brain volume.
RESULTS: There were highly significant relationships between valence and amygdala volume asymmetry. Increased negativity of memories was associated with larger right amygdala volumes in Left TLE patients (r=.7, p[lt].01) and with larger left amygdala/temporal volumes in Right TLE patients (r=-.825, p[lt].02). In contrast to emotional memory, mood (Beck, PANAS) was strongly related to hippocampal asymmetries among the Left, but not Right TLE group. Decreased left hippocampal volumes were particularly associated with somatic and vegetative symptoms. Importantly, the two epilepsy groups did not differ on any of the mood measures, although both scored significantly higher than the controls.
CONCLUSIONS: These data suggest that mesial temporal lobe dysfunction may differentially influence two components of emotional behavior - [underline]mood[/underline] and [underline]personal memories[/underline] of emotional events. Although inter-related, our findings suggest that emotional memories, expecially those that are more negative and aversive, may be particularly influenced by amygdalar volumetric asymmetries. Depressed mood, especially somatic components, may be more associated with hippocampal volume asymmetries among patients with left TLE.
Support: NIH (NS32911) and University of Florida Clinical Research Center