The Postsubiculum and Spatial Learning: The Role of Postsubicular Synaptic Activity and Synaptic Plasticity in Hippocampal Place Cell, Object, and Object-Location Memory

David Bett, Cassie H. Stevenson, Kate L. Shires, Michael T. Smith, Stephen J. Martin, Paul A. Dudchenko, Emma R. Wood

Research output: Contribution to journalArticlepeer-review

Abstract

Visual landmarks exert stimulus control over spatial behavior and the spatially tuned firing of place, head-direction, and grid cells in the rodent. However, the neural site of convergence for representations of landmarks and representations of space has yet to be identified. A potential site of plasticity underlying associations with landmarks is the postsubiculum. To test this, we blocked glutamatergic transmission in the rat postsubiculum with CNQX, or NMDA receptor-dependent plasticity with D-AP5. These infusions were sufficient to block evoked potentials from the lateral dorsal thalamus and long-term depression following tetanization of this input to the postsubiculum, respectively. In a second experiment, CNQX disrupted the stability of rat hippocampal place cell fields in a familiar environment. In a novel environment, blockade of plasticity with D-AP5 in the postsubiculum did not block the formation of a stable place field map following a 6 h delay. In a final behavioral experiment, postsubicular infusions of both compounds blocked object-location memory in the rat, but did not affect object recognition memory. These results suggest that the postsubiculum is necessary for the recognition of familiar environments, and that NMDA receptor-dependent plasticity in the postsubiculum is required for the formation of new object-place associations that support recognition memory. However, plasticity in the postsubiculum is not necessary for the formation of new spatial maps.

Original languageEnglish
Pages (from-to)6928-6943
Number of pages16
JournalJournal of Neuroscience
Volume33
Issue number16
DOIs
Publication statusPublished - 17 Apr 2013

Keywords

  • LONG-TERM POTENTIATION
  • RECEPTOR BLOCKADE
  • HEAD-DIRECTION CELLS
  • ENTORHINAL CORTEX
  • EXCITOTOXIC LESIONS
  • RETROSPLENIAL CORTEX
  • POSTRHINAL CORTEX
  • FREELY-MOVING RATS
  • PREFRONTAL CORTEX
  • PARASUBICULUM DISRUPT

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