Sparsity of Population Activity in the Hippocampus Is Task-Invariant Across the Trisynaptic Circuit and Dorsoventral Axis

IF 2.4 3区 医学 Q3 NEUROSCIENCES
Hippocampus Pub Date : 2024-12-02 DOI:10.1002/hipo.23651
J. Quinn Lee, Matt Nielsen, Rebecca McHugh, Erik Morgan, Nancy S. Hong, Robert J. Sutherland, Robert J. McDonald
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引用次数: 0

Abstract

Evidence from neurophysiological and genetic studies demonstrates that activity sparsity—the proportion of neurons that are active at a given time in a population—systematically varies across the canonical trisynaptic circuit of the hippocampus. Recent work has also shown that sparsity varies across the hippocampal dorsoventral (long) axis, wherein activity is sparser in ventral than dorsal regions. While the hippocampus has a critical role in long-term memory (LTM), whether sparsity across the trisynaptic circuit and hippocampal long axis is task-dependent or invariant remains unknown. Importantly, representational sparsity has significant implications for neural computation and theoretical models of learning and memory within and beyond the hippocampus. Here we used functional molecular imaging to quantify sparsity in the rat hippocampus during performance of the Morris water task (MWT) and contextual fear discrimination (CFD) – two popular and distinct assays of LTM. We found that activity sparsity is highly reliable across memory tasks, wherein activity increases sequentially across the trisynaptic circuit (DG < CA3 < CA1) and decreases across the long axis (ventral<dorsal). These results have important implications for models of hippocampal function and suggest that activity sparsity is a preserved property in the hippocampal system across cognitive settings.

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来源期刊
Hippocampus
Hippocampus 医学-神经科学
CiteScore
5.80
自引率
5.70%
发文量
79
审稿时长
3-8 weeks
期刊介绍: Hippocampus provides a forum for the exchange of current information between investigators interested in the neurobiology of the hippocampal formation and related structures. While the relationships of submitted papers to the hippocampal formation will be evaluated liberally, the substance of appropriate papers should deal with the hippocampal formation per se or with the interaction between the hippocampal formation and other brain regions. The scope of Hippocampus is wide: single and multidisciplinary experimental studies from all fields of basic science, theoretical papers, papers dealing with hippocampal preparations as models for understanding the central nervous system, and clinical studies will be considered for publication. The Editor especially encourages the submission of papers that contribute to a functional understanding of the hippocampal formation.
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