Derosiere et al., Neuroimage 2016
Zénon et al., Brain stimulation 2015
In these recent experiments, we used repetitive TMS (continuous theta burst stimulation) to disrupt activity in the primary motor cortex (M1) while participants performed a value-based choice reaction time task. The data provide evidence for a distinct contribution of M1 to value-based reinforcement learning and value-based motor decision making.
Wilhelm et al., Frontiers in Human Neuroscience 2016
Many studies have investigated corticospinal (CS) excitability changes associated with various aspects of action preparation. To date, these studies have used a "Single-Coil" Method whereby motor-evoked potential (MEP) are elicited in a single hand muscle following TMS over the contralateral primary motor cortex (M1). In the future, it would be really convenient to obtain measures of CS excitability in both hands by using a “Double-Coil” Method with TMS applied over both M1 at the same time. The first tests are encouraging but further experiments are required to determine the best parameters to be used when applying this new method.
Zénon et al., Brain 2016
The subthalamic nucleus (STN) is a region of the basal ganglia which is centrally involved in the pathophysiology of Parkinson disease and which is thought to be important for adjusting behaviour during conflict situations. In this study, we show that the neural activity recorded in the subthalamic nucleus of implanted Parkinson patients signals the subjective value of effortful tasks rather than decision conflict. This points to the possible role of this region in controlling motivation and task engagement.
Zénon et al. The Journal of Neuroscience (in press)
Tonic dopamine has been proposed to signal the average value of all the actions that one could perform at any given time. This value of time could then be used to estimate the opportunity cost of a decision. If true, dopamine should affect response vigor only in situations in which it impacts on action duration. However, we found the opposite, suggesting that instead of signalling opportunity cost, dopamine influences the ratio between the effort cost linked to action execution, and its expected value.