fMRI correlates of reward processing in medial temporal lobe epilepsy (pre and post surgery)
Background: The medial temporal lobe (MTL) structures, including the hippocampus and the amygdala, and their connections with cortical and subcortical pathways, play a core role in different cognitive processes, including the reward processing. However, the specific roles of the hippocampus and amygdala to reward processing are not fully understood. Studying patients diagnosed with medial temporal lobe epilepsy and hippocampal sclerosis (mTLE-HS) before and after surgery provides a great opportunity to investigate the impact of MTL dysfunction on related brain networks.
Objective: This study aimed to investigate the role of the MTL in reward processing by examining the specific vulnerability of these structures in a group of patients with mTLEHS, compared to healthy controls, before and after epilepsy surgery to understand the repercussions of surgical resection of the MTL on this process. Using functional magnetic resonance imaging data that were collected during a gambling task.
Method: Twenty-four patients with mTLE-HS counterbalanced with 20 healthy controls performed a modified version of a gambling task while functional magnetic resonance imaging (fMRI) was obtained simultaneously.
Results: In the first session, before surgery, whole-brain level analysis revealed significant difference in brain activity primarily within the right insula-amygdala (unaffected side). Further post-hoc analysis showed that these differences were mainly found in the loss condition. In contrast, in the second session, mTLE patients after surgery showed higher activity within the the subgyral and right parahippocampal gyrus on the unaffected side compared to controls. Notably, specific differences in the nucleus accumbens were observed on the resected side. These results contribute to a deeper understanding of the role played by the hippocampus and amygdala in the reward system and have implications for the management of presurgial mTLE patients.
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ZOOM LINK: https://ub-edu.zoom.us/j/91235728676
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