RT Journal Article
SR Electronic
T1 Hippocampal network reorganization underlies the formation of a temporal association memory
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 613638
DO 10.1101/613638
A1 Mohsin S. Ahmed
A1 James B. Priestley
A1 Angel Castro
A1 Fabio Stefanini
A1 Elizabeth M. Balough
A1 Erin Lavoie
A1 Luca Mazzucato
A1 Stefano Fusi
A1 Attila Losonczy
YR 2019
UL http://biorxiv.org/content/early/2019/04/18/613638.abstract
AB Episodic memory requires linking events in time, a function dependent on the hippocampus. In “trace” fear conditioning, animals learn to associate a neutral cue with an aversive stimulus despite their separation in time by a delay period on the order of tens of seconds. But how this temporal association forms remains unclear. Here we use 2-photon calcium imaging to track neural population dynamics over the complete time-course of learning and show that, in contrast to previous theories, the hippocampus does not generate persistent activity to bridge the time delay. Instead, learning is concomitant with broad changes in the active neural population in CA1. While neural responses were highly stochastic in time, cue identity could be reliably read out from population activity rates over longer timescales after learning. These results question the ubiquity of neural sequences during temporal association learning, and suggest that trace fear conditioning relies on mechanisms that differ from persistent activity accounts of working memory.