title: Muscimol, AP5, or scopolamine infused into perirhinal cortex impairs two-choice visual discrimination learning in rats.
abstract: The perirhinal cortex (PRh) has been strongly implicated in object recognition memory and visual stimulus representation. Studies of object recognition have revealed evidence for the involvement of several neurotransmitter subsystems, including those involving NMDA (N-methyl-d-aspartic acid) and muscarinic cholinergic receptors. In the present study, we assessed the possible involvement of PRh and related receptor subsystems in two-choice visual discrimination learning by Lister Hooded rats tested in touchscreen-equipped operant boxes. In Experiment 1, daily pre-training inactivation of PRh with the GABA(A) receptor agonist muscimol (0.5 microg/hemisphere) significantly impaired acquisition of the two-choice visual discrimination. In Experiment 2, daily pre-training blockade of either NMDA or muscarinic receptors in PRh with AP5 (5.9 microg/hemisphere) or scopolamine (10 microg/hemisphere), respectively, impaired task acquisition. These results parallel the findings from object recognition studies and suggest a generality of neurotransmitter receptor involvement underlying the role of PRh in both object recognition memory and visual discrimination learning. The involvement of PRh in both types of tasks may be related to its role in complex visual stimulus representation.
authors.affiliation: Department of Experimental Psychology, University of Cambridge, Downing St., Cambridge CB2 3EB, UK. bwinters@uoguelph.ca
authors.forename: Boyer D
authors.initials: BD
authors.lastname: Winters
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Bartko
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Saksida
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Bussey
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology*; D000818:Animals; D004192:Discrimination, Psychological / Q000187:drug effects / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology; D058785:GABA-A Receptor Agonists; D007858:Learning / Q000187:drug effects* / Q000502:physiology; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009118:Muscimol / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D012601:Scopolamine / Q000494:pharmacology*; D013702:Temporal Lobe / Q000187:drug effects* / Q000502:physiology; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018755:GABA Agonists; D058785:GABA-A Receptor Agonists; D018727:Muscarinic Antagonists; D018377:Neurotransmitter Agents; D011963:Receptors, GABA-A; D011976:Receptors, Muscarinic; D016194:Receptors, N-Methyl-D-Aspartate; D009118:Muscimol; D015763:2-Amino-5-phosphonovalerate; D012601:Scopolamine