Abstracts

Rationale: The amygdaloid complex, containing a total of thirteen nuclei, plays a critical role in mediating bodily responses to stress and fear. Due to its innervations to the hippocampus, the amygdala has been recognized as a critical structure implicated in mesial temporal lobe epilepsy (MTLE). Variable intracranial electroencephalogram (icEEG) electrophysiological signals of amygdala recording during stimuli or seizure have been reported, all to underscore the diversity and complexities of subnuclei within the amygdaloid complex. Yet, the distinct functional connectivity patterns among these subnuclei remain relatively unclear. Herein, our research focused on exploring the connectivity differences between the ventral (basal and lateral nuclei) and dorsal (medial and central nuclei) regions of the amygdala during the interictal and ictal phase in a small cohort of MTLE patients (n=9).

Methods: To investigate the neuronal connectivity between the amygdala to different regions in the brain, a coherence analysis of the stereo-electroencephalogram (SEEG) signals was performed across 162 seizures within 9 patients. For each seizure, 20 seconds of background recording and 100 seconds of ictal data were analyzed. SEEG data from all contacts implanted were high-pass filtered using a third-order Butterworth filter with a cutoff frequency of 1 Hz. Coherence was estimated for 5-second SEEG sliding windows overlapping by 1 second for the entirety of the inter-ictal and ictal segments, respectively. Analysis was separated by frequency bands up to 200Hz, accounting for delta [0.5 – 4Hz], theta [4 – 7Hz], alpha [8 – 13Hz], beta [13 – 35Hz], low gamma [35 – 60Hz], high gamma [60 – 90Hz] waves, and beyond [90 – 200Hz]. Coherence values were calculated across contacts. Contacts in specific Regions of Interest (ROIs) with reported associations with the amygdala were identified. Bootstrap analysis was performed to compare the coherence values of the ROIs with respect to the dorsal and ventral amygdala with an alpha value defined as p < 0.05. Diffusion tensor imaging (DTI) tractography analysis was performed to characterize dorsal and ventral amygdala output tracts.