Carsten Mehring (Institute of Biology III, Freiburg & Bernstein Center Freiburg) | Human motor control: structures, skills and movement decisions

Abstract

The only way we can interact with the world is through movement: be it by using tools, speaking or walking. The human motor system is capable of learning a seemingly infinite amount of movement skills, surpassing such abilities of any man-made robot. The computational and neuronal mechanisms of human dexterity and adaptation abilities remain elusive. In this presentation I will discuss a few recent advances we have made to improve our understanding of human motor control and learning:

(i) After extensive practice with motor tasks sharing structural similarities (e.g., different dancing movements), new tasks of the same type can be learned faster. According to our “structure learning” hypothesis, such rapid generalization relies on learning the dynamic and kinematic relationships shared by a set of tasks. As a consequence, adaptation becomes constrained, effectively leading to a dimensionality reduction of the learning problem. I will present experimental evidence for the “structure learning’’ hypothesis from various kinds of motor tasks.

(ii) While recent research on motor learning has been mostly focused on motor adaptation following visuomotor or force perturbations, acquisition of motor skill is a difficult and controversial topic that remains poorly understood. Even though there is no universally accepted definition of motor skill, it is clear that skill acquisition is very different from adaptation. I will present a novel experimental paradigm, which allows us to study motor learning in the absence of external perturbations and also any repeated movement sequences. In this experimental condition subjects demonstrate genuine skill acquisition and I will discuss possible changes in the motor system accompanying this learning.

(iii) The influence of the phase of transcranial alternating current stimulation has been previously shown to influence behavior by modifying the expression of tremor in patients with Parkinson’s disease, additionally it has also been shown to influence perception of near threshold sounds. Here, I will present our finding that tACS can also influence the timing of decision making in a phase specific way, without the conscious knowledge of the subject.