Moving at a self-selected pace: vigor, inter-individual differences and the cost of time theory
Lieu : salle de réunion de l’INCIA
(Université Paris-Sud, http://hebergement.u-psud.fr/berret/ )
Invitant : Aymar de Rugy
Abstract: In daily life we often move at a self-selected pace, thereby choosing certain relationships between amplitude, speed or duration, i.e. movement vigor. Yet, the principles underlying the formation of movement vigor remain unclear. If basal ganglia dysfunction clearly affects movement vigor, as exemplified by bradykinesia in Parkinson’s patients, relatively large inter-individual differences have also been reported among healthy participants performing various motor tasks such as saccades, walking or reaching. Biomechanics (e.g. anthropometry) likely contributes to inter-individual differences but recently a “cost of time” theory has been proposed to be the cornerstone of such differences in movement invigoration. It assumes that the brain puts a cost on time during the neural control of movement. In this talk, I will review earlier theories that have been proposed to account for the vigor of human movement and motivate the cost of time theory as a normative means to predict the vigor of self-paced arm movements. The proposed theory can account for the formation of movement vigor as well as for inter-individual differences beyond simple biomechanical discrepancies. The consistency of the cost of time across modeling choices, tasks or repeated measurements will then be explored, and future works will be discussed. Overall, the formation of vigor is a central (yet still intriguing) aspect of human motor behavior that seems to require a multidisciplinary approach lying at the interface of mathematics, biomechanics, neurophysiology and psychology, to be better understood.