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Title: Offline memory replay in recurrent neuronal networks emerges from constraints on online dynamics
AbstractDuring spatial exploration, neural circuits in the hippocampus store memories of sequences of sensory events encountered in the environment. When sensory information is absent during ‘offline’ resting periods, brief neuronal population bursts can ‘replay’ sequences of activity that resemble bouts of sensory experience. These sequences can occur in either forward or reverse order, and can even include spatial trajectories that have not been experienced, but are consistent with the topology of the environment. The neural circuit mechanisms underlying this variable and flexible sequence generation are unknown. Here we demonstrate in a recurrent spiking network model of hippocampal area CA3 that experimental constraints on network dynamics such as population sparsity, stimulus selectivity, rhythmicity and spike rate adaptation, as well as associative synaptic connectivity, enable additional emergent properties, including variable offline memory replay. In an online stimulus‐driven state, we observed the emergence of neuronal sequences that swept from representations of past to future stimuli on the timescale of the theta rhythm. In an offline state driven only by noise, the network generated both forward and reverse neuronal sequences, and recapitulated the experimental observation that offline memory replay events tend to include salient locations like the site of a reward. These results demonstrate that biological constraints on the dynamics of recurrent neural circuits are sufficient to enable memories of sensory events stored in the strengths of synaptic connections to be flexibly read out during rest and sleep, which is thought to be important for memory consolidation and planning of future behaviour.image Key pointsA recurrent spiking network model of hippocampal area CA3 was optimized to recapitulate experimentally observed network dynamics during simulated spatial exploration.During simulated offline rest, the network exhibited the emergent property of generating flexible forward, reverse and mixed direction memory replay events.Network perturbations and analysis of model diversity and degeneracy identified associative synaptic connectivity and key features of network dynamics as important for offline sequence generation.Network simulations demonstrate that population over‐representation of salient positions like the site of reward results in biased memory replay.  more » « less
Award ID(s):
1811597
PAR ID:
10493251
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
John Wiley & Sons Ltd on behalf of The Physiological Society.
Date Published:
Journal Name:
The Journal of Physiology
Volume:
601
Issue:
15
ISSN:
0022-3751
Page Range / eLocation ID:
3241 to 3264
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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