Ensemble place codes in hippocampus: CA1, CA3, and dentate gyrus place cells have multiple place fields in large environments

Previously we reported that the hippocampus place code must be an ensemble code because place cells in the CA1 region of hippocampus have multiple place fields in a more natural, larger-than-standard enclosure with stairs that permitted movements in 3-D. Here, we further investigated the nature of h...

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Bibliographic Details
Published in:PloS one 2011-07, Vol.6 (7), p.e22349
Main Authors: Park, Eunhye, Dvorak, Dino, Fenton, André A
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Animals
Biology
Brain
CA1 Region, Hippocampal - physiology
CA3 Region, Hippocampal - physiology
Codes
Cylinders
Dentate gyrus
Dentate Gyrus - physiology
Early retirement
Enclosures
Environment
Estimates
Feeding Behavior - physiology
Firing (igniting)
Firing pattern
Forage
Hippocampus
Male
Neurosciences
Physiology
Rats
Rats, Long-Evans
Rodents
Sleep
Subdivisions
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Summary:Previously we reported that the hippocampus place code must be an ensemble code because place cells in the CA1 region of hippocampus have multiple place fields in a more natural, larger-than-standard enclosure with stairs that permitted movements in 3-D. Here, we further investigated the nature of hippocampal place codes by characterizing the spatial firing properties of place cells in the CA1, CA3, and dentate gyrus (DG) hippocampal subdivisions as rats foraged in a standard 76-cm cylinder as well as a larger-than-standard box (1.8 m×1.4 m) that did not have stairs or any internal structure to permit movements in 3-D. The rats were trained to forage continuously for 1 hour using computer-controlled food delivery. We confirmed that most place cells have single place fields in the standard cylinder and that the positional firing pattern remapped between the cylinder and the large enclosure. Importantly, place cells in the CA1, CA3 and DG areas all characteristically had multiple place fields that were irregularly spaced, as we had reported previously for CA1. We conclude that multiple place fields are a fundamental characteristic of hippocampal place cells that simplifies to a single field in sufficiently small spaces. An ensemble place code is compatible with these observations, which contradict any dedicated coding scheme.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0022349