Memory Retrieval Evaluation In A Microcircuit Model Of The Hippocampus

Authors: Nikolas Andreakos, Shigang Yue, Vassilis Cutsuridis

Presenting author: Vassilis Cutsuridis

Presentation type: Poster at SNUFA 2024 online workshop (5-6 Nov 2024)

Abstract

Memory retrieval is important in how the already stored information can be accessed. Improving it would help in developing strategies for preventing memory loss. We selectively scaled excitatory and inhibitory responses of key CA1 neurons to evaluate memory retrieval as a function of stored patterns, pattern interference, contexts, network size, and engram cells in a computational circuit model of the hippocampus. Model excitatory and inhibitory cells fired at specific phases of a theta oscillation imposed by an external inhibitory signal targeting only inhibitory cells, which inhibited compartments of excitatory cells. Sensory and contextual inputs targeting cell dendrites caused cells to fire. Simulation results showed scaling of excitatory synapses in proximal but not basal dendrites of bistratified cells inhibiting pyramidal cells made retrieval perfect. Scaling of inhibitory synapses in pyramidal cells made retrieval worst. Decreases in the number of memory engram cells improved memory retrieval in a pathway-dependent way. Increases in network size and stored patterns had a minimal effect on memory retrieval. Memory interference had a detrimental effect on memory retrieval, which was reversible as the number of engram cells decreased. Changes in contextual information made memory retrieval worse confirming previous evidence that more familiar context facilitates memory retrieval.