Notes of the course part 2

Pagina 1

1 Computational Neuroscience Motor control and learning The general brain objective is to generate the movement. Movement is our only instrument for active interaction with the external world. Obvious examples range from expression of complex thoughts (writing, reading, talking, communicating…) to artistic production, sportive tasks, interpersonal relationships… Movement is a complex task for several reasons: - Delays: there are delays both in the transduction of motor command from the Central Nervous System (CNS) to the muscular system and in the conduction processes of sensorial signals to the CNS. Sensorial delays, moreover, combine with delays associated with movement itself. This delay makes the sensorial information unusable to guide at leas t the initial part of the movement. Skilled performances need open loop control: PREDICTION! There are intrinsic delays. And these are even higher than the execution of the movement. When we dive, we took some time before because we need to make predictions and planning. - Noise: besides delays, both sensorial inputs and motor control signals are subject to intrinsic neural noise that limits the motor system ability to simultaneously execute FAST and ACCURATE movements. To overcome this noise, the motor syst em has to combine actual sensorial data with a direct model: PLANNING. Planning allows, thanks to experience, the ability to induct the correct information from a noisy signal. - Not stationary: the relation between motor commands and movement (dynamic) changes with time by two different points of view. First, there is an ontogenetic factor, i.e. living subjects grow up and second, our motor task actuation changes with respect to different objects and different environments. Training as well as pathologies continuously…