Time-limited modulation of appetitive Pavlovian memory by D1 and NMDA receptors in the nucleus accumbens.
Recent research has implicated the nucleus accumbens (NAc) in consolidating recently acquired goal-directed appetitive memories, including spatial learning and other instrumental processes. However, an important but unresolved issue is whether this forebrain structure also contributes to the consolidation of fundamental forms of appetitive learning acquired by Pavlovian associative processes. In addition, although dopaminergic and glutamatergic influences in the NAc have been implicated in instrumental learning, it is unclear whether similar mechanisms operate during Pavlovian conditioning. To evaluate these issues, the effects of posttraining intra-NAc infusions of D1, D2, and NMDA receptor antagonists, as well as d-amphetamine, were determined on Pavlovian autoshaping in rats, which assesses learning by discriminated approach behavior to a visual conditioned stimulus predictive of food reward. Intracerebral infusions were given either immediately after each conditioning session to disrupt early memory consolidation or after a delay of 24 h. Findings indicate that immediate, but not delayed, infusions of both D1 (SCH 23390) and NMDA (AP-5) receptor antagonists significantly impair learning on this task. By contrast, amphetamine and the D2 receptor antagonist sulpiride were without significant effect. These findings provide the most direct demonstration to date that D1 and NMDA receptors in the NAc contribute to, and are necessary for, the early consolidation of appetitive Pavlovian learning.
Dalley
Jeffrey W
JW
Department of Experimental Psychology, Downing Street, University of Cambridge, Cambridge CB2 3EB, United Kingdom. jwd20@cam.ac.uk
Lääne
Kristjan
K
Theobald
David E H
DE
Armstrong
Hannah C
HC
Corlett
Philip R
PR
Chudasama
Yogita
Y
Robbins
Trevor W
TW
D000818:Animals; D001066:Appetite / Q000502:physiology*; D001552:Benzazepines / Q000494:pharmacology; D001931:Brain Mapping; D003214:Conditioning, Classical / Q000502:physiology*; D003913:Dextroamphetamine / Q000494:pharmacology; D006185:Habituation, Psychophysiologic; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D017447:Receptors, Dopamine D1 / Q000187:drug effects / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D013469:Sulpiride / Q000494:pharmacology; D013997:Time Factors
D001552:Benzazepines; D017447:Receptors, Dopamine D1; D016194:Receptors, N-Methyl-D-Aspartate; D013469:Sulpiride; D003913:Dextroamphetamine