The Journal of Neuroscience, October 1, 2000, 20(19):7463-7477
The Involvement of Recurrent Connections in Area CA3 in
Establishing the Properties of Place Fields: a Model
Szabolcs
Káli1, 2 and
Peter
Dayan1
1 Gatsby Computational Neuroscience Unit, University
College London, London WC1N 3AR, United Kingdom, and
2 Department of Brain and Cognitive Sciences, Massachusetts
Institute of Technology, Cambridge, Massachusetts 02139
Strong constraints on the neural mechanisms underlying the
formation of place fields in the rodent hippocampus come from the systematic changes in spatial activity patterns that are consequent on
systematic environmental manipulations. We describe an attractor network model of area CA3 in which local, recurrent, excitatory, and
inhibitory interactions generate appropriate place cell representations from location- and direction-specific activity in the entorhinal cortex.
In the model, familiarity with the environment, as reflected by
activity in neuromodulatory systems, influences the efficacy and
plasticity of the recurrent and feedforward inputs to CA3. In
unfamiliar, novel, environments, mossy fiber inputs impose activity
patterns on CA3, and the recurrent collaterals and the perforant path
inputs are subject to graded Hebbian plasticity. This sculpts CA3
attractors and associates them with activity patterns in the entorhinal
cortex. In familiar environments, place fields are controlled by the
way that perforant path inputs select among the attractors.
Depending on the training experience provided, the model generates
place fields that are either directional or nondirectional and whose
changes when the environment undergoes simple geometric transformations
are in accordance with experimental data. Representations of multiple
environments can be stored and recalled with little interference, and
these have the appropriate degrees of similarity in visually similar environments.
Key words:
hippocampus; place cells; CA3; recurrent network; plasticity; familiarity; neuromodulation; directionality; attractor; model
Copyright © 2000 Society for Neuroscience 0270-6474/00/20197463-15$05.00/0
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