Glutamatergic contributions to nicotine-induced cognitive enhancement

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The neuroscience of social interaction rapidly grows in importance. Key among the neural substrates of emotion processing in social interaction is the amygdala. The amygdala is known to orchestrate aversive and appetitive reinforcement learning through the monitoring of environmental signals of positive and negative emotional value. The most prototypical such signal is the human face, and both fearful and happy faces act as reinforcers in that they enable the observer to rapidly learn which behaviors or objects to approach or avoid. Accumulating evidence suggests that reinforcement learning is dysfunctional in drug addiction. Central to the proposed fMRI project is the assumption that if (1) amygdala function is critical for reinforcement learning, and if (2) nicotine addiction is associated with dysregulated reinforcement learning, then nicotineaddicted subjects should present with amygdala dysfunction. Specifically, we hypothesize that functional, volumetric, and topological abnormalities may exist in the amygdala of nicotine-dependent subjects that may either represent a predisposition to nicotine addiction or a nicotine-induced neuroadaptation. The proposed fMRI project specifically addresses the effects of nicotine dependence on amygdala-dependent emotion pocessing in social stimuli. Given the observation of higher rates of nicotine dependence among female than male smokers, we hypothesize that the amygdala s functional, volumetric, and topological abnormalities may be more pronounced in women than in men.