Orbitofrontal cortex integrates amygdala-hippocampal information and guides schema-based emotional categorization
Jie Zheng1, Jack J. Lin1,2; 1University of California, Irvine, 2Comprehensive Epilepsy Program, Irvine, CA
Repeated emotional experiences provide a cognitive map or mental “schema” to facilitate acquisition of new emotional information, shape individuals’ personalities, and guide interpersonal communications. The orbitofrontal cortex (OFC), hippocampus (HPC), and amygdala (AMY) are critical for schema formation, decision-making and emotional processing. However, despite anatomical links among these structures, the network oscillatory dynamics that support schema-based emotional processing in humans are unclear. We recorded intracranial electroencephalography from 7 pre-surgical epilepsy patients implanted with depth electrodes to characterize the OFC-HPC-AMY dynamics. During the task, participants were instructed to either categorize the face with the appropriate linguistic label of the emotion (e.g. sad, happy, afraid), which will elicit participants’ prior emotional knowledge (schema condition) or match the face with the one having the same emotional expression (non-schema condition). We observed faster reaction time (t-test, P = 0.013) and stronger low frequency synchrony (permutation test, P < 0.01) within the tripartite network for the schema compared to the non-schema condition. Moreover, the dimensionality of the network was reduced for the schema condition, with the OFC served as the hub modulating HPC and AMY high frequency activities at distinct theta phases for different emotional categories. For one patient with bilateral OFC lesions, impaired behavioral performance was observed only in the schema condition, with no dimensional reduction in the medial temporal lobe network. These findings provide causal evidence that the OFC serves to integrate new emotional information into existing schema by reducing the dimensionality of the space humans have to search to learn new information.
Topic Area: EMOTION & SOCIAL: Emotion-cognition interactions