Thesis title: Reward Size and Motor Effort Modulate the Activity of Phasically Active Neurons in the Monkey Striatum
Motivation underlies human behavior. Over the years, motivation has been studied under many aspects, both from a psychological and neurophysiological point of view. Several brain areas have been involved in the motivational process, but it seems that the striatum plays a fundamental role given its implication in the reward system. To investigate the role of the striatum in motivation, and the role that force and reward play in the modulation of the phasically active neurons of the striatum, two monkeys were used in a task in which the monkeys had to modulate the force exerted on a lever (high or low) to receive two different amounts of rewards (high or low) at the end of the trial. Behavioral results showed that monkeys preferred the high reward condition over the low reward condition. At the neural level, we have identified three different subpopulations of phasically active neurons that had a peak of activation centred on three different period of the task. The neural analyses showed how all three populations were modulated by both force and reward, thus showing the involvement of the striatum in the motivational process. Analysis with the decoding algorithm also showed that these neurons were modulated by force and reward even outside their peak of maximum activity.