title: The postsubiculum and spatial learning: the role of postsubicular synaptic activity and synaptic plasticity in hippocampal place cell, object, and object-location memory.
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.
authors.affiliation: Centre for Cognitive and Neural Systems, School of Biomedical Sciences, University of Edinburgh, Edinburgh EH8 9JZ, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Bett
authors.forename: Cassie H
authors.initials: CH
authors.lastname: Stevenson
authors.forename: Kate L
authors.initials: KL
authors.lastname: Shires
authors.forename: Michael T
authors.initials: MT
authors.lastname: Smith
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Martin
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dudchenko
authors.forename: Emma R
authors.initials: ER
authors.lastname: Wood
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005106:Exploratory Behavior / Q000187:drug effects; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010775:Photic Stimulation; D051381:Rats; D021641:Recognition, Psychology; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology*; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate