Multiplexing of Theta and Alpha Rhythms in the Amygdala-Hippocampal Circuit Supports Pattern Separation of Emotional Information

Abstract

How do we remember emotional events? While emotion often leads to vivid recollection, the precision of emotional memories can be degraded, especially when discriminating among overlapping experiences in memory (i.e. pattern separation). Communication between the amygdala and the hippocampus has been proposed to support emotional memory but the exact neural mechanisms are not well understood. Here, we used intracranial depth electrode recordings in pre-surgical epilepsy patients to show that successful pattern separation of emotional stimuli is associated with theta band (3-7 Hz)-coordinated bidirectional interactions between the amygdala and the hippocampus. In contrast, we show that overgeneralization is associated with alpha band (7-13 Hz)-coordinated unidirectional influence from the amygdala to the hippocampus. These findings imply that alpha band synchrony may trigger overgeneralization of similar emotional events via amygdala-hippocampal directional coupling, which suggests a target for the treatment of psychiatric conditions such as post-traumatic stress disorder, where aversive memories are often overgeneralized.