The Roles of Left and Right Prefrontal Cortex in Cognitive and Emotional Conditions in Epilepsy Patients with Intracranial EEG

Introduction: The dorsal anterior cingulate cortex (dACC) and dorsolateral prefrontal cortex (DLPFC) within the prefrontal cortex play pivotal roles in cognitive and emotional processing. Understanding the lateralized functions of these regions may aid in developing therapeutic strategies for epilepsy. This study aimed to evaluate the roles of the left and right dACC and DLPFC in cognitive and emotional conditions among epilepsy patients.

Methods: Five patients with long-standing pharmacoresistant complex partial seizures and normal brain imaging participated in the study. All were undergoing invasive intracranial electroencephalogram (iEEG) monitoring to identify seizure foci before epilepsy surgery. Participants performed two conflict-based tasks: the Multi-Source Interference Task (MSIT) to assess cognitive processing and the Emotional Conflict Resolution (ECR) task to evaluate emotional processing. Data analyses included event-related potentials (ERPs), time-frequency analysis, and Phase Slope Index (PSI) to determine the directionality of information flow between brain regions.

Results: Mean reaction times for both congruent and incongruent conditions of the MSIT were significantly longer than those for the ECR task (P < 0.001). Additionally, reaction times in incongruent conditions were substantially higher than in congruent conditions for both tasks (P < 0.05). In the left dACC and DLPFC, ERP activities for the ECR task (both congruent and incongruent) were significantly higher after the stimulus compared to the MSIT (P < 0.001). Conversely, the MSIT elicited substantially higher activity during the response window than the ECR task (P < 0.05). The right dACC and DLPFC showed greater ERP activities for the MSIT after the stimulus and higher activity for the ECR task during the response window (P < 0.05). All patients demonstrated a weak inter-hemispheric correlation between the left and right prefrontal hemispheres (P < 0.05), but a strong intra-hemispheric correlation within each prefrontal lobe (P < 0.001).

Conclusion : The distinct activation patterns and connectivity observed in the prefrontal cortices during cognitive and emotional tasks highlight the complexity of neural processing in these domains. These findings could inform therapeutic strategies, such as targeted deep brain stimulation, to treat cognitive and emotional impairments in epilepsy patients.