Inactivation of prelimbic and infralimbic cortex respectively affects minimally-trained and extensively-trained goal-directed actions

Abstract

Several studies have examined a role for the prelimbic cortex (PL) and infralimbic cortex (IL) in free operant behavior. The general conclusion has been that PL controls goal-directed actions (instrumental behaviors that are sensitive to reinforcer devaluation) whereas IL controls habits (instrumental behaviors that are not sensitive to reinforcer devaluation). To further examine the involvement of these regions in the expression of instrumental behavior, we first implanted male rats with bilateral guide cannulae into their PL, then trained two responses to produce a sucrose pellet reinforcer, R1 and R2, each in a distinct context. R1 received extensive training and R2 received minimal training. Rats then received lithium chloride injections either paired or unpaired with sucrose pellets in both contexts until paired rats rejected all pellets. Following acquisition, in Experiment 1, rats received either an infusion of saline or baclofen/muscimol into the PL and were tested (in extinction) on both R1 and R2. In vehicle controls, both responses were goal-directed actions, as indicated by their sensitivity to reinforcer devaluation. PL inactivation decreased expression of the minimally-trained action without affecting expression of the extensively-trained action. Experiment 2 utilized the same experimental design but with IL inactivation at test. The extensively-trained response was again a goal-directed action. However, now expression of the extensively-trained goal-directed action was suppressed by IL inactivation. The overall pattern of results suggests that the PL is involved in expression of minimally trained goal-directed behavior while the IL is involved in expression of extensively trained goal-directed behavior. This implies that the PL does not control all types of actions and the IL can control some types of actions. These results expand upon the traditional view that the PL controls action while the IL controls habit.

Chemogenetic Silencing of Prelimbic Cortex to Anterior Dorsomedial Striatum Projection Attenuates Operant Responding

“…The current results contrastingly show that a PL-to-a more aDMS pathway is important in the expression of operant responding early in training. This is unlikely to be a motor-related effect, given that studies have demonstrated that pharmacological inactivation of the PL (and therefore all of its projections) reduces only minimally-trained responding, and only in the acquisition context, while leaving other responses unaffected (Killcross and Coutureau, 2003; Trask et al, 2017; Shipman et al, 2018). Finally, we confirmed with ex vivo patch-clamp electrophysiology that cells in layer 5 of the PL expressing the DREADD-mCherry construct reporter showed attenuated spiking in the presence of CNO.…”

“…The prelimbic cortex (PL) has been well established as a mediator of operant (instrumental) responses early in training (Corbit and Balleine, 2003; Killcross and Coutureau, 2003; Ostlund and Balleine, 2005; Tran-Tu-Yen et al, 2009; Trask et al, 2017; Shipman et al, 2018). The dorsomedial striatum (DMS) has similarly been implicated in the acquisition and expression of operant responding, with a particular emphasis on the posterior DMS (pDMS; Yin et al, 2005a,b; Shiflett et al, 2010).…”

“…The PL has been implicated in the expression of minimally-trained operant responding when testing occurs in the acquisition context (Trask et al, 2017; Shipman et al, 2018). Temporary inactivation of the PL with baclofen/muscimol at the time of test following six daily sessions of acquisition (lever press training) resulted in an attenuation of operant responding in the context where training had been conducted, but not in another context (Trask et al, 2017).…”

Prolonged avoidance training exacerbates OCD-like behaviors in a rodent model

“…Thus, avoidance in the 20d group does not appear to be mediated by the previously described avoidance circuit 35,40 . In fact, persistent 20d rats showed less activity in PL than persistent 8d rats, suggesting that expression of persistent avoidance shifts through different circuits over the course of avoidance training 31,41 . Indeed, a negative correlation between PL activity and avoidance was observed in overtrained rats either receiving 4 or 10 days of Ext-RP.…”

Involvement of the rodent prelimbic and medial orbitofrontal cortices in goal‐directed action: A brief review

“…The rodent mPFC can be subdivided into multiple regions with specific functions, and >2 decades of research indicate that the prelimbic (PL) subregion is necessary for learning about relationships between actions and their outcomes (Figure ). PL inactivation in both mice and rats interferes with the ability of rodents to learn action–outcome associations (Balleine & Dickinson, ; Corbit & Balleine, ; Coutureau, Esclassan, Scala, & Marchand, ; Coutureau, Marchand, & Scala, ; Dutech, Coutureau, & Marchand, ; Killcross & Coutureau, ; Ostlund & Balleine, ; Shipman, Trask, Bouton, & Green, ; Swanson, DePoy, & Gourley, ; Tran‐Tu‐Yen, Marchand, Pape, Scala, & Coutureau, ). In instrumental reversal tasks (i.e., reversal tasks in which rodents must modify learned response strategies, rather than stimulus–outcome associations), PL inactivation can also delay response acquisition (de Bruin et al, ; but see Dalton, Wang, Phillips, & Floresco, ; Gourley, Lee, Howell, Pittenger, & Taylor, ), consistent with the notion that the PL is necessary for flexibly directing actions toward valued outcomes by encoding action–outcome associations.…”