Inactivation of the prelimbic cortex attenuates operant responding in both physical and behavioral contexts.

ABSTRACT

The present experiments aimed to expand our understanding of the role of the prelimbic cortex (PL) in the contextual control of instrumental behavior. Research has previously shown that the PL is involved when the "physical context," or chamber in which an instrumental behavior is trained, facilitates performance of the instrumental response (Trask, Shipman, Green, & Bouton, 2017). Recently, evidence has suggested that when a sequence of two instrumental behaviors is required to earn a reinforcing outcome, the first response (rather than the physical chamber) can be the "behavioral context" for the second response (Thrailkill, Trott, Zerr, and Bouton, 2016). Could the PL also be involved in this kind of contextual control? Here rats first learned a heterogenous behavior chain in which the first response (i.e., pressing a lever or pulling a chain) was cued by a discriminative stimulus and led to a second stimulus which cued a second response (i.e., pulling a chain or pressing a lever); the second response led to a sucrose reward. When the first and second responses were tested in isolation in the training context, pharmacological inactivation of the PL resulted in a reduction of the first response, but not the second response. When the second response was performed in the "context" of the first response (i.e., as part of the behavior chain) however, PL inactivation reduced the second response. Overall, these results support the idea that the PL is important for mediating the effects of a training context on instrumental responding, whether the context is physical or behavioral.