A limited role for mediodorsal thalamus in devaluation tasks.

Full Abstract

Six experiments were performed to determine the role of mediodorsal thalamus (MD) in the devaluation task, varying the type of contingencies (Pavlovian or operant), the number of reinforcers (one vs. two), and the order of experiments (in naïve or experimentally experienced rats). MD-lesioned rats were impaired in devaluation performance when switched between Pavlovian and operant devaluation tasks, but not when switched from one Pavlovian devaluation task to another Pavlovian devaluation task. MD lesions caused no devaluation impairment in a multiple-reinforcer Pavlovian devaluation task. These results suggest that MD lesions impair performance in devaluation tasks as a result of an inability to switch the form of associations made from one type of outcome-encoding association to another. This is in accord with previous literature suggesting that MD is needed for strategy set shifting. The results further suggest that MD is a necessary part of devaluation circuits only in cases in which previous associations need to be suppressed in order for new associations to be learned and control behavior, and otherwise the devaluation circuit does not require MD.(Copyright) 2008 APA, all rights reserved.

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Author information

Author/s: Pickens, Charles L (CL);

Affiliation: Department of Psychological and Brain Sciences, Johns Hopkins University, USA.

Grants: MH53667 (Agency:United States NIMH) ; MH65879 (Agency:United States NIMH)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.

Journal: Behavioral neuroscience (Behav Neurosci), published in United States. (Language: eng)

Reference: 2008-Jun; vol 122 (issue 3) : pp 659-76

Dates: Created 2008/06/02; Completed 2008/08/13;

PMID: 18513136, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Analysis of Variance
Animals
Appetitive Behavior
Association
Avoidance Learning
Behavior, Animal
Conditioning, Classical - physiology
Conditioning, Operant - physiology

Conditioning, Operant - physiology
Extinction, Psychological - physiology
Male
Mediodorsal Thalamic Nucleus - injuries; physiology
Rats
Rats, Long-Evans
Reinforcement (Psychology)
Reinforcement Schedule

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