Effect of NMDA lesion on habitual behavior (2012)

Undergraduates: Katie Joa, none none Dr. Tatiana Shnitko

Faculty Advisor: Donita Robinson
Department: Psychology & Neuroscience

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Habit formation contributes to drug and alcohol addiction, which is why investigation of habitual behavior is especially interesting. Previous research has shown the ventral prefrontal cortex plays a role in the development and maintenance of habitual behavior; however the role of the dorsomedial prefrontal cortex is still not widely understood. The present study served to investigate the effect of NMDA lesion in the dorsomedial prefrontal cortex (dmPFC) on habitual reward-seeking behaviors. Male Long-Evans rats were trained to self-administer a sucrose solution (10%) on a VI30s schedule of reinforcement in operant chambers, which has been shown to produce habitual behavior. Once rats developed habit, determined based on a specific satiety devaluation procedure, stereotaxic surgery was performed in order to insert a double guide cannula into the dmPFC (AP 2.7mm; ML 0.5mm). Rats were trained to re-establish self-administration behavior. Then animals were separated into experimental and control groups. To cause lesion in dmPFC, NMDA was infused in experimental group and PBS 7.4 was infused as a sham control. The specific satiety devaluation procedure was performed again in order to determine effect of lesion on habitual behavior. The results of specific satiety devaluation procedures revealed that all animals developed habitual self-administration behavior prior to the lesion. Post lesion devaluation procedures revealed that the habitual behavior of the rats was destroyed and became goal-directed in both the experimental and sham lesion control groups. Based on these results, it is unclear whether the NMDA lesion in dmPFC or surgery affected the animal’s behavior.