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Frédéric Ambroggi

Integrative properties of the Nucleus Accumbens : which information is conveyed by ventral tegmental area, basolateral amygdala and prefrontal inputs ?

University of California, San Francisco.

The nucleus accumbens (NAc) is critical for the control of reward-related behaviors. This brain region seems particularly implicated in linking exteroceptive and interoceptive stimuli to rewarded actions. NAc neurons are activated or inhibited by reward predictive stimuli. I have recent evidence that this firing pattern is both necessary and sufficient for operant responding controlled by incentive stimuli. My previous work focused on which input regions controlled the firing of NAc neurons, using freely moving electrophysiology. Inactivation of ventral tegmental area, basolateral amygdala and prelimbic cortex reduced operant responding to reward predictive stimuli as well as NAc neuronal responses to such stimuli. On the contrary, infralimbic cortex inactivation had no effect on reward predictive stimulus responding. Instead it increased unrewarded actions. Strong evidence suggests that this effect depends on an opposite modulation and excited and inhibited NAc neurons. My current work focuses on understanding which information is conveyed to the NAc via these inputs. Responding to incentive stimuli necessitate to (1) know what the stimulus predicts (e.g. reward value) and (2) use this knowledge to perform, if desired, the required actions to obtain the reward (e.g. motivation). I have evidence that both reward value and motivation may be encoded by ventral tegmental area neurons while basolateral amygdala neurons carry the former but not the latter.