A cortical cell ensemble in the posterior parietal cortex controls past experience-dependent memory updating

Akinobu Suzuki,Eri Sasakawa,Kaoru Inokuchi,Emi Murayama,Hirokazu Hirai,Noriaki Ohkawa,Ayumu Konno,Sakurako Kosugi

doi:10.1038/s41467-021-27763-x

Akinobu Suzuki, Eri Sasakawa + Show 6 more

Open Access

https://doi.org/10.1038/s41467-021-27763-x

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Abstract

When processing current sensory inputs, animals refer to related past experiences. Current information is then incorporated into the related neural network to update previously stored memories. However, the neuronal mechanism underlying the impact of memories of prior experiences on current learning is not well understood. Here, we found that a cellular ensemble in the posterior parietal cortex (PPC) that is activated during past experience mediates an interaction between past and current information to update memory through a PPC-anterior cingulate cortex circuit in mice. Moreover, optogenetic silencing of the PPC ensemble immediately after retrieval dissociated the interaction without affecting individual memories stored in the hippocampus and amygdala. Thus, a specific subpopulation of PPC cells represents past information and instructs downstream brain regions to update previous memories.

Highlights

When processing current sensory inputs, animals refer to related past experiences
Our study reveals that a posterior parietal cortex (PPC) cell ensemble recruited during a past experience acts as a top-down modulator for the interaction between recalled memory and ongoing experience
Our findings suggest that the PPC cell ensemble that is activated during past experience acts as a sensory buffer for use in a future relevant experience

Summary

Introduction

Current information is incorporated into the related neural network to update previously stored memories. A specific subpopulation of PPC cells represents past information and instructs downstream brain regions to update previous memories. Recent studies have begun to clarify the mechanisms underlying memory engrams and how prior experiences affect later learning. Sharing of engram cell populations mediates the interaction between the prior and the later memories[6,7,8,9,10]. By taking advantage of a simple behavioral task in which mice associate a past experience (context) with a current sensory input (footshock) during one learning session, we show that a specific subpopulation of cells in PPC governs past event-dependent memory update. The PPC cell ensemble has characteristics distinct from the engram cell ensemble as it does not encode information of individual events, rather it controls the interaction between past and current memory events

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