Prelimbic cortex inactivation prevents ABA renewal based on satiety state.

We have previously shown that the rat prelimbic cortex (PL) is necessary for contexts to promote the performance of instrumental behaviors that have been learned in them, whether the context is physical (operant chamber) or behavioral (recent performance of a behavior that has historically preceded the target in a behavior chain). In the present experiment, we investigated the role of the PL in satiety level as an interoceptive acquisition context. Rats were trained to lever-press for sweet/fat pellets while sated (22 hrs continuous food access) followed by the extinction of the response while hungry (22 hrs food deprived). Pharmacological inactivation of the PL (with baclofen/muscimol infusion) attenuated renewal of the response that occurred upon a return to the sated context. In contrast, animals that received a vehicle (saline) infusion showed renewal of the previously extinguished response. These results support the hypothesis that the PL monitors the relevant contextual elements (physical, behavioral, or satiety state) associated with reinforcement of a response and promotes the subsequent performance of that response in their presence.

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

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.

Chemogenetic inhibition of the ventral hippocampus but not its direct projection to the prelimbic cortex attenuates context-specific operant responding.

Previous work has demonstrated the importance of the prelimbic cortex (PL) in contextual control of operant behavior. However, the associated neural circuitry responsible for providing contextual information to the PL is not well understood. In Pavlovian fear conditioning the ventral hippocampus (vH) and its projection to the PL have been shown to be important in supporting the effects of context on learning. The present experiments used chemogenetic inhibition of the direct vH-PL projection or the vH to determine involvement in expression of context-specific operant behavior. Rats were injected with an inhibitory DREADD (hM4Di) or mCherry-only into the vH, and subsequently trained to perform a lever press response for a food pellet in a distinct context. The DREADD ligand clozapine-n-oxide (CNO) was then delivered directly into the PL (experiment 1) and then systemically (experiment 2) prior to tests of the response in the training context as well as an equally familiar but untrained context. vH (systemic CNO) but not vH-PL (intra-PL CNO) inhibition was found to attenuate operant responding in its acquisition context. A third experiment, using the same rats, showed that chemogenetic inhibition of vH also reduced Pavlovian contextual fear. The present results suggest that multisynapatic connections between the vH and PL may be responsible for integration of contextual information with operant behavior.

Prelimbic cortex inactivation prevents ABA renewal based on stress state.

Our recent research suggests that the interoceptive state associated with stress can function as a contextual stimulus for operant behavior. In the present experiment, we investigated the role of the rodent prelimbic cortex (PL), a brain region that is critical in contextual control of operant behavior, in the ability of a stressed state to produce ABA renewal of an extinguished operant response. Rats were trained to perform a lever press response for a food pellet reward during daily sessions that followed exposure to a stressor that changed each day. The response was then extinguished in the absence of stress. ABA renewal of extinguished responding occurred following exposure to another stressor (different from any used during acquisition) in control rats but not in rats that received a PL-inactivating infusion (baclofen/muscimol). Results confirm that the interoceptive state of stress can play the role of a contextual stimulus and initiate renewal (relapse) of an inhibited behavior when stress has previously been associated with the behavior. In conjunction with our previous work, the present results support the hypothesis that the PL is important for contexts, both exteroceptive and interoceptive, to exert such control over operant behavior. (PsycInfo Database Record (c) 2023 APA, all rights reserved).