My research focuses on the neuroscience of movement control and decision making with a special interest for the brain mechanisms underlying the integration of cognition into action planning.

One focus of this research is to understand how motor decisions are made in the brain. At every moment, the world presents us with many opportunities for action. In the presence of such a continuous flow of external information, we have to make decisions in order to select actions that will provide us with the largest satisfaction. Choices may involve deciding which restaurant to frequent on a Friday evening or the best route to take to avoid holiday traffic. There are also many simple actions that require a choice to be made. For example, we often have to decide to pick up an object such as a cup of coffee with the left or right hand. The fluid and flexible manner with which we make such decisions indicates the operation of a selection process that takes into account multiple factors such as the relative position of the hand with respect to the object, handedness, contextual rules and anticipated consequences based on previous experience. A number of current projects are concerned with the study of how these cognitive factors are integrated to form motor decisions. In a series of experiments, we test the hypothesis that decisions are the product of an integrative process involving the concurrent activation of multiple action plans competing for selection within the motor cortex.

I am also interested in understanding the role played by inhibitory mechanisms in action planning. Converging lines of evidence suggest that inhibition is an important aspect of movement control. For example, the two hemispheres exert mutual inhibitory influences and an alteration of these interactions contributes to the motor deficits observed in stroke patients. Besides, the importance of inhibition has also been highlighted in the context of response selection and impulse control. I am interested in characterizing these functions of inhibition and in evaluating the possibility that impaired decision making in elderly subjects is, at least in part, due to a deficit in inhibitory control, resulting in suboptimal selective attention and response selection processes.

In order to address these research questions, we use behavioral tasks combined with different forms of non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS), electroencephalography (EEG) and functional magnetic resonance imaging (fMRI).

We use transcranial magnetic stimulation (TMS) to assess corticospinal excitability during the preparation of motor responses. This allows investigating the involvement of excitatory and inhibitory influences targeted at the motor cortex during hand selection.

 

We also use TMS to induce "virtual lesions" of trageted brain regions. This allows us to assess their functional contribution to specific behaviours.

 

We use electroencephalography (EEG) to assess the interactions between selective attention in visual cortical areas and response selection in motor-related areas.

To evaluate visual attention we use the steady-state visual evoked technique (SSVEP).

We can study response selection by measuring lateralized evoked potentials (LRPs) or by applying TMS over the primary motor cortex (M1).

 

In a recent collaboration involving researchers from the Institute of Neuroscience at the UCL (Jean-Louis Thonnard) and the University of Montreal (Ignasi Cos), we assessed the neural substrates of affordances in the context of response selection. To do so, we used a task which required subjects (Jean-Louis Thonnard on this picture) to grasp a beer mug with a commensurate or incommensurate grip.

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