Characterizing the Neural Bases of Motivational Disorders After Stroke

Disorders of motivation, such as apathy, are among the most prevalent symptoms in neuropsychiatric disorders and during chronic diseases. They have a major impact on patients' physical activity and lifestyle, and on their involvement in their own care. They affect a wide range of morbidity outcomes, alter functional recovery in rehabilitation, impair long-term disability, and prevent patients from returning to an active and independent life. Yet, the neural bases of motivational deficits remain largely unknown. Current diagnostic tools are sparse and cannot distinguish between distinct mechanisms responsible for apathetic syndromes. Besides, current treatments remain extremely limited. However, recent advances in the field of neuroeconomics - the science of decision-making - have provided concept and tools to study the neurobiological bases of elementary cognitive processes underlying motivated behaviors. These theories suggest that the brain implements optimization processes that determine our behaviors by minimizing the cost of our actions while maximizing their expected benefits. The adaptation of tools developed for basic research now enables the assessment of these cognitive mechanisms.

Elementary deficits of motivation will be assessed with a phenotyping battery of motivation tests in 20 healthy subjects (up to 10 healthy subjects can be replaced), 20 patients (up to 10 patients can be replaced) with a stroke in the medial prefrontal cortex, and 20 patients (up to 10 patients can be replaced) with a stroke in the insula. This battery will allow us to characterize, at the patient's level, elementary processes such as the encoding of goal values or effort costs, the modulation of cost with fatigue, and the resolution of cost-benefit trade-offs. Symptom-Lesion mapping studies and voxel-based morphometry studies will be performed using whole brain MRI measures of structural integrity.