The influence of NMDA receptors in the dorsomedial striatum on response reversal learning

In mammals, the dorsomedial striatum is one brain area shown to be critical for the flexible shifting of response patterns. At present, the neurochemical mechanisms that underlie learning during a shift in response patterns are unknown. The present study examined the effects of NMDA competitive anta...

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Bibliographic Details
Published in:Neurobiology of learning and memory 2004-09, Vol.82 (2), p.81-89
Main Authors: Palencia, Carlos A., Ragozzino, Michael E.
Format: Article
Language:English
Subjects:
2-Amino-5-phosphonovalerate - administration & dosage
Animal
Animals
AP-5
Basal ganglia
Behavioral flexibility
Biological and medical sciences
Discrimination Learning - drug effects
Discrimination Learning - physiology
Dose-Response Relationship, Drug
Excitatory Amino Acid Antagonists - administration & dosage
Fundamental and applied biological sciences. Psychology
Learning
Learning. Memory
Male
Maze Learning - drug effects
Maze Learning - physiology
Memory
Microinjections
Neostriatum - drug effects
Neostriatum - metabolism
NMDA
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Rats
Rats, Long-Evans
Receptors, N-Methyl-D-Aspartate - metabolism
Reversal Learning - physiology
Striatum
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Summary:In mammals, the dorsomedial striatum is one brain area shown to be critical for the flexible shifting of response patterns. At present, the neurochemical mechanisms that underlie learning during a shift in response patterns are unknown. The present study examined the effects of NMDA competitive antagonist, dl-2-amino-5-phosphonopentanoic acid (AP-5), injected into the dorsomedial striatum on the acquisition and reversal of a response discrimination. Male Long-Evans rats were tested across two consecutive days in a modified cross-maze. Rats received an infusion of either saline or AP-5 (5 or 25 nmol) 5 min prior to each test session. In the acquisition phase rats learned to turn in one direction (right or left) to receive a cereal reinforcement. In the reversal learning phase rats learned to turn in the opposite direction as in the acquisition phase. In both phases, criterion was achieved when a rat made 10 consecutive correct trials. Infusions of AP-5 did not impair acquisition, but impaired reversal learning of a response discrimination in a dose-dependent fashion. The reversal learning deficit induced by AP-5 resulted from reversions back to the originally learned response pattern following the initial shift. These results suggest that activation of NMDA receptors in the dorsomedial striatum are critical for the flexible shifting of response patterns by enhancing the reliable execution of a new response pattern under changing task contingencies.
ISSN:1074-7427
1095-9564
DOI:10.1016/j.nlm.2004.04.004