NMDA and D2-like receptors modulate cognitive flexibility in a color discrimination reversal task in pigeons.
Reversal and extinction learning represent forms of cognitive flexibility that refer to the ability of an animal to alter behavior in response to unanticipated changes on environmental demands. A role for dopamine and glutamate in modulating this behavior has been implicated. Here, we determined the effects of intracerebroventricular injections in pigeons' forebrain of the D2-like receptor agonist quinpirole, the D2-like receptor antagonist sulpiride and the N-methyl-d-aspartate receptor antagonist AP-5 on initial acquisition and reversal of a color discrimination task. On day one, pigeons had to learn to discriminate two color keys. On day two, pigeons first performed a retention test, which was followed by a reversal of the reward contingencies of the two color keys. None of the drugs altered performance in the initial acquisition of color discrimination or affected the retention of the learned color key. In contrast, all drugs impaired reversal learning by increasing trials and incorrect responses in the reversal session. Our data support the hypothesis that D2-like receptor mechanisms, like N-methyl-d-aspartate receptor modulations, are involved in cognitive flexibility and relearning processes, but not in initial learning of stimulus-reward association.
Institute for Cognitive Neuroscience, Department of Biopsychology, Faculty of Psychology, Ruhr University Bochum. Christina.Herold@uni-duesseldorf.de
Christina
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Herold
D000818:Animals; D002404:Catheterization; D003071:Cognition / Q000187:drug effects / Q000502:physiology*; D003116:Color; D010856:Columbidae; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D003463:Cues; D004192:Discrimination, Psychological / Q000187:drug effects / Q000502:physiology*; D065127:Dopamine D2 Receptor Antagonists; D056344:Executive Function / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects / Q000502:physiology; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D016548:Prosencephalon / Q000187:drug effects / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012193:Reversal Learning / Q000187:drug effects / Q000502:physiology*; D012201:Reward; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology*
D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D016194:Receptors, N-Methyl-D-Aspartate