ORIGINAL RESEARCH article
Front. Cell. Neurosci.
Sec. Cellular Neurophysiology
This article is part of the Research TopicMemory processing in health and disease: linking behavioral, circuits, and molecular scales.View all 6 articles
Between Similarity and Difference: Network Dynamics of the Hippocampal-Parahippocampal Circuitry in Pattern Separation of male Wistar Rats
Provisionally accepted
Ana Paula de Castro Araujo
Jeanderson Soares Parente
Sofia Lucena de Oliveira Coutinho
Rochele Castelo-Branco
Ywlliane S. R. Meurer
Flávio F Barbosa*- Psychology, Federal University of Paraíba, João Pessoa, Brazil
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Studies indicate that pattern separation for spatial and object information involves structures of the temporal cortex (lateral entorhinal and perirhinal cortices) and hippocampus (dentate gyrus and CA3), which are particularly sensitive to aging. However, little is known about how the hippocampal network, the anteroposterior axis of these regions, and the excitatory-inhibitory circuit contribute to the recognition and separation of object patterns. This study investigated the expression of c-Fos and PV along the anteroposterior axis of the hippocampus in a multi-trial task to assess the recognition of novel objects and recognition of novel objects with different levels of similarity. Five groups of animals performed tasks with different similarity demands (NOR, DIST, 25%, 50%, 75%). The data showed that conditions of greater similarity led to increased c-Fos expression in CA3c and Hilus in the rostral hippocampus. Graph analysis revealed that hippocampal networks became more densely interconnected and efficient as object similarity increased. Furthermore, different patterns of cluster organization emerged depending on task demands. Besides, the granule cell layer along the dorsoventral axis exhibited greater activation of inhibitory neurons (PV+/c-Fos+) under conditions of higher similarity. Differential inhibitory/excitatory control of the DG-CA3 microcircuit network is seen across conditions. Modeling the DG layers revealed robust control of GCs through direct and indirect effects of interneurons present in the hilus and granule layer. Bidirectional direct and indirect effects of MCs on GCs were observed. These results contribute to our understanding of how brain networks and DG excitatory/inhibitory microcircuits are jointly engaged in object recognition memory and disambiguation of overlapping inputs.
Keywords: object recognition memory, Pattern Separation, Hippocampal network, graph analysis, Dentate Gyrus, PV cells
Received: 17 Jun 2025; Accepted: 27 Oct 2025.
Copyright: © 2025 de Castro Araujo, Soares Parente, Lucena de Oliveira Coutinho, Castelo-Branco, Meurer and Barbosa. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Flávio F Barbosa, barbosa.flaviof@gmail.com
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