Brain research
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The prefrontal cortex plays an important role in shaping cognition and behavior. Many studies have shown that medial prefrontal cortex (mPFC) plays a key role in seeking, extinction, and reinstatement of cocaine seeking in rodent models of relapse. Subregions of mPFC appear to play distinct roles in these behaviors, such that the prelimbic cortex (PL) is proposed to drive cocaine seeking and the infralimbic cortex (IL) is proposed to suppress cocaine seeking after extinction. ⋯ We also present recent results calling the absolute nature of a PL vs. IL dichotomy into question. Finally, we consider alternate functions for mPFC that correspond less to response execution and inhibition and instead incorporate the complex cognitive behavior for which the mPFC is broadly appreciated.
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Drug addiction is a chronic, relapsing brain disorder characterized by compulsive drug use. Contemporary addiction theories state that loss of control over drug use is mediated by a combination of several processes, including a transition from goal-directed to habitual forms of drug seeking and taking, and a breakdown of the prefrontally-mediated cognitive control over drug intake. In recent years, substantial progress has been made in the modelling of loss of control over drug use in animal models, but the neural substrates of compulsive drug use remain largely unknown. ⋯ Pharmacological inactivation of the PrL, using the GABA receptor agonists baclofen and muscimol, reduced conditioned suppression of cocaine and sucrose seeking in animals with limited self-administration experience. Inactivation of the OFC did not influence conditioned suppression, however. These data indicate that reduced neural activity in the PrL promotes persistent seeking behaviour, which may underlie compulsive aspects of drug use in addiction.