PhD Defence Dr. Inge Tuitert

On November 6, Inge Tuitert defended her thesis entitled "Synergies and end-effector kinematics in upper limb movements”.

Her research took place at the UMCG’s Department of Movement Sciences in collaboration with Aix-Marseille University. In her thesis, Dr. Tuitert investigates the problem concerning degrees of freedom. Motor tasks are never executed in the exact same fashion when performed repeatedly, because many degrees of freedom, such as joints and muscles, are involved. This results in many different solutions to perform the same motor task.

To coordinate the redundant degrees of freedom, synergies are introduced. A synergy is defined as the temporary link of degrees of freedom into task specific units. Kay (1988) described a synergy as the first step in a two-step process resulting from the interactions between environment, organism and task factors. In the second step, factors interact with the synergy, resulting in specific behaviour.

Most importantly, this thesis shows that some task factors are involved mainly in the first step of the two-step process, while other task factors typically influence the second step. This suggests two-step process plays a role in the coordination of redundant degrees of freedom.