Dynamic Interactions of Emotional States, Temporal Coding and Memory
We hypothesize that the rate of change of the similarity of hippocampal- EC multivariate neural activity patterns will be slower following negative events, which will persist to influence the encoding of later-experienced neutral events, including visually evoked contextual shifts.
Time unfolds continuously, but our temporal memories are fragmented—particularly under stress. Accumulating evidence indicates that intense negative emotional events can distort temporal perception, and, consequently, the fundamental organization of episodic memories, i.e., knowing what happened when. However, the neural mechanisms underlying emotion-driven distortions in temporal coding, and whether those distortions can be counteracted, are unknown. Accurate temporal coding is essential for optimal behavior not only during dynamically unfolding situations requiring time-sensitive action, but also for future inference, which is informed by temporally-bound event memories.
We have recently developed a new paradigm to study emotion-temporal interactions, which indicates that negative events distort memory for temporal duration of prior events. Here, we combine this new behavioral assay and insights with advanced neuroimaging and a novel, individualized brain stimulation protocol to test the following three hypotheses:
(1) Intense emotional events distort temporal encoding via amygdalar projections to the hippocampus, which compete with environmentally driven, temporal context input emanating from entorhinal cortex, resulting in the reduced autocorrelation of multivariate neural activity patterns in the hippocampus following emotional compared to neutral events (a robust neural correlate of accurate temporal memory).
(2) The magnitude of emotion-driven distortions in temporal memory depends on changes in sympathetic arousal.
(3) Non-invasive, individualized, network-based brain stimulation (transcranial magnetic stimulation) targeting the hippocampus will enhance the fidelity of temporal coding and counteract the typically deleterious impact of acute emotional events on temporal memory.
