Amygdala lesions are associated with improved mood after epilepsy surgery

Abstract

Neuroimaging studies in healthy and clinical populations strongly associate the amygdala with emotion, especially negative emotions. The consequences of surgical resection of the amygdala on mood are not well characterized. We tested the hypothesis that amygdala resection would result in mood improvement. In this study, we evaluated a cohort of 52 individuals with medial temporal lobectomy for intractable epilepsy who had resections variably involving the amygdala. All individuals achieved good post-surgical seizure control and had pre- and post-surgery mood assessment with the Beck Depression Inventory (BDI) ratings. We manually segmented the surgical resection cavities and performed multivariate lesion-symptom mapping of change in BDI. Our results showed a significant improvement in average mood ratings from pre- to post-surgery across all patients. In partial support of our hypothesis, resection of the right amygdala was significantly associated with mood improvement (r = 0.5, p = 0.008). The lesion-symptom map also showed that resection of the right hippocampus and para-hippocampal gyrus was associated with worsened post-surgical mood. Future studies could evaluate this finding prospectively in larger samples while including other neuropsychological outcome measures.

Keywords: Amygdala; Lesion symptom mapping; Mood changes; Temporal lobe epilepsy.

Fig. 1

a Lesion overlap. Lesion overlap map of the surgical resection cavities used in this analysis (N = 52), with a peak overlap in the left medial temporal lobe n = 28 of 52 at (− 40, − 4, − 25). b Multivariate lesion-symptom mapping. The lesion-symptom map of participants with right hemisphere lesions, showing an association of right amygdala lesions with improvement in post-surgical mood, with voxel weights displayed using a unit-less scale with values closer to 1 reflecting a stronger lesion–mood association. (r = 0.5, p = 0.008). c Lesion proportional subtraction map. The image on the left shows the location of the amygdala and hippocampus in green and blue, respectively, as a reference. The image on the right shows proportional subtraction results, where the red color scale displays regions preferentially associated with improved mood and the blue color scale displaying regions associated with mood worsening. Note the sharp contrast that respects that anatomical boundary between the hippocampus and amygdala, with hippocampus lesions more commonly associated with mood worsening and amygdala lesions associated with a higher likelihood of post-surgical improvement in mood