The Role of the Rat Medial Prefrontal Cortex in Adapting to Changes in Instrumental Contingency
PLoS ONE. 2012-04-04; 7(4): e33302
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1. PLoS One. 2012;7(4):e33302. doi: 10.1371/journal.pone.0033302. Epub 2012 Apr 4.
The role of the rat medial prefrontal cortex in adapting to changes in
Coutureau E(1), Esclassan F, Di Scala G, Marchand AR.
(1)Institut de Neurosciences Cognitives et Intégratives d’Aquitaine (INCIA),
Université de Bordeaux, Talence, France.
In order to select actions appropriate to current needs, a subject must identify
relationships between actions and events. Control over the environment is
determined by the degree to which action consequences can be predicted, as
described by action-outcome contingencies–i.e. performing an action should
affect the probability of the outcome. We evaluated in a first experiment
adaptation to contingency changes in rats with neurotoxic lesions of the medial
prefrontal cortex. Results indicate that this brain region is not critical to
adjust instrumental responding to a negative contingency where the rats must
refrain from pressing a lever, as this action prevents reward delivery. By
contrast, this brain region is required to reduce responding in a non-contingent
situation where the same number of rewards is freely delivered and actions do not
affect the outcome any more. In a second experiment, we determined that this
effect does not result from a different perception of temporal relationships
between actions and outcomes since lesioned rats adapted normally to gradually
increasing delays in reward delivery. These data indicate that the medial
prefrontal cortex is not directly involved in evaluating the correlation between
action–and reward–rates or in the perception of reward delays. The deficit in
lesioned rats appears to consist of an abnormal response to the balance between
contingent and non-contingent rewards. By highlighting the role of prefrontal
regions in adapting to the causal status of actions, these data contribute to our
understanding of the neural basis of choice tasks.
PMID: 22496747 [Indexed for MEDLINE]