We know little about the role of serotonin and dopamine in decision making and motivation. Using dietary amino-acid depletion, Jan Gläscher and I showed that dopamine and serotonin can play different roles in these processes. We know that the presence of appetitive stimuli (e.g. food when you are hungry) can increase the energy with which you carry out your responses, and the presence of aversive stimuli can reduce this energy. Using a paradigm called Pavlovian-to-instrumental transfer we showed that this motivating effect of appetitive stimuli can be eliminated when reducing dopamine, and that this demotivating effect of aversive stimuli can become even stronger when reducing serotonin. Interestingly, another motivational component - that to avoid aversive stimuli by inhibiting behavior - can show the opposite effect when serotonin is reduced.

Currently, I am investigating the representational format of multi-step value-based decisions (more to come soon...)