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Multiple dopamine systems

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Tuesday, May 02, 2017
12:00 pm - 1:00 pm
Nao Uchida; Hosted by Rebecca Yang
Neurobiology Invited Seminar Series

Dopamine is a neuromodulator that plays important roles in reward-based learning, motivation and movement. However, the nature of dopamine signals remains debated. It has been postulated that dopamine signals reward prediction error or the discrepancy between actual and predicted reward. However, increasing evidence suggests that dopamine neurons projecting to different targets encode different information. For instance, it has been shown that different parts of the striatum receive distinct dopamine signals. In a recent study (Menegas et al., 2017), we have compared dopamine axon signals in the ventral striatum ("VS dopamine") and the "tail" of the striatum ("TS dopamine") using fiber fluorometry (photometry). TS dopamine showed strong excitation to novel odor cues, whereas VS dopamine showed no responses to novel odor cues. Additionally, TS dopamine showed excitation to several types of stimuli including rewarding, aversive, and neutral stimuli whereas VS dopamine showed excitation only to reward or reward-predicting cues. Together, these results demonstrated that there are distinct populations of dopamine neurons, one signaling reward prediction error (VS dopamine) and another signaling salience (TS dopamine). These results suggest that we need a better theory to account for the nature of dopamine signals as well as the function of dopamine.

Contact: Rebecca Yang