Masakazu Taira, Serotonergic Effects on Motor Actions for Future Rewards in Mice

Speaker: Masakazu Taira, Neural Computation (Doya) Unit

Title: Serotonergic effects on motor actions for future rewards in mice

Abstract: 

Serotonin (5-HT) is an important neuromodulator on behavioral, affective, and cognitive functions. Recent studies showed that the optogenetic activation of 5-HT neurons promotes patience to wait for future rewards. However, it remains unclear through which process 5-HT prolonged waiting through increased action persistence/behavioral activation or behavioural inhibition. To solve this question, we trained Tph2- ChR2 transgenic mice to perform an operant conditioning task of variable numbers of lever-presses, in which action persistence and behavioural inhibition can be behaviourally separated, and tested the effect of optogenetic activation of 5-HT neurons in the dorsal raphe nucleus (DRN). In this task mice could obtain the reward by pressing a lever at required ratio and reward is omitted in 20% of trials in a session (reward omission trial). In the reward omission trials, optogenetic activation neither inhibited nor promoted action persistence which were mainly indicated by the number of lever-presses and the time from the first lever-press to the last lever-press. The inter-press intervals (IPIs), the duration between two neighboring presses, showed a tendency to increase toward the end of a trial, but 5-HT neuron activation did not affect IPIs, suggesting no effect of the ontogenetic activation on response vigors of motor actions. These results suggest that serotonergic effect on motor action differs from that on stationary waiting. In addition to the results I have gained so far, I am going to talk next question to be solved and future experiment with some preliminary results.

After the seminar (17:00-17:30), join us for discussion with free pizza and soft drinks!