anisomycin and maltodextrin

The evidence for a role of the striatum in the acquisition of uncued instrumental responding is ambiguous. It has been shown that post-session infusions of anisomycin into the core of the nucleus accumbens (NAcc) impaired instrumental acquisition, but pre-training lesions of the NAcc suggest that it is not necessary. Recently, we demonstrated that the infusion of anisomycin into the anterior cingulate cortex impaired instrumental acquisition indirectly through a taste aversion. Thus, we hypothesized that post-session anisomycin infusions into the NAcc affected instrumental acquisition through an effect on reinforcer valuation. For the dorsal striatum, both post-session infusions of anisomycin and pre-training lesion studies suggest that neither the dorsolateral nor the dorsomedial striatum is necessary for the acquisition of instrumental responding. However, it has not been attempted to block plasticity in both regions concurrently, and we hypothesized that both regions independently contribute to acquisition through goal-directed and habitual learning. In the current experiments, we first replicated the effect of unprotected post-session anisomycin infusions into the NAcc on instrumental acquisition. Subsequently, we investigated the effect of protein synthesis inhibition in the NAcc and dorsomedial and dorsolateral striatum concurrently on instrumental acquisition, critically controlling for effects on reinforcer valuation. The anisomycin infusions induced an aversive state, but did not affect instrumental acquisition.

Topics: Analysis of Variance; Animals; Anisomycin; Conditioning, Operant; Corpus Striatum; Male; Nucleus Accumbens; Polysaccharides; Protein Synthesis Inhibitors; Rats; Reinforcement, Psychology; Time Factors

The integrity of the rodent anterior cingulate cortex (ACC) is essential for various aspects of instrumental behavior, but it is not clear if the ACC is important for the acquisition of a simple instrumental response. Here, it was demonstrated that post-session infusions of anisomycin into the rat ACC completely prevented the acquisition of instrumental responding. The experimental use of post-session intracranial infusions of plasticity inhibitors is assumed to affect local consolidation of plasticity, but not behavioral task performance. However, in associative appetitive conditioning, post-session intracranial infusion of pharmaco-active compounds could actually interfere with subsequent task performance indirectly through retrospective effects on the valuation of ingested rewards. Thus, it was subsequently demonstrated that the intracranial infusion of anisomycin into the ACC after sucrose pellet consumption significantly reduced subsequent pellet consumption, suggesting that the infusion of anisomycin into the ACC produced conditioned taste avoidance. In the third experiment, an innovative procedure was introduced that dissociated the effects of intracranial infusions after conditioning sessions on task-learning and unconditioned stimulus valuation. With this procedure, the infusion of anisomycin into the ACC after instrumental sessions did not affect instrumental reinforcer valuation or the acquisition of instrumental responding, suggesting that plasticity in the ACC is not necessary for the acquisition of instrumental behavior.

Topics: Analysis of Variance; Animals; Anisomycin; Conditioning, Operant; Food Preferences; Gyrus Cinguli; Learning Disabilities; Male; Polysaccharides; Protein Synthesis Inhibitors; Rats; Reinforcement Schedule; Reinforcement, Psychology; Sucrose; Sweetening Agents; Time Factors