Recovery of arm and hand function after stroke is essential for self-independence. It is unknown why some individuals recover hand function and others do not. One determining factor is whether the cortico-spinal tract is damaged. A factor which might indicate early recovery of hand function is the neural coupling mechanism that coordinates bilateral hand movements in daily life activities. An early prediction of recovery is essential for the planning of appropriate rehabilitation procedures. The newly discovered neural coupling mechanism is reflected in the appearance of compensatory reflex reactions to unilateral displacements in the forearm muscles not only of the disturbed but also of the contralateral side during daily life cooperative hand movements. In post-stroke subjects impaired hand function was shown to be associated with a defective neural coupling of upper limbs. This was suggested to be due to an impaired processing of sensory input from the affected side.

We plan an observational study to investigate the reorganizational process of neural coupling underlying cooperative hand movements in acute post-stroke patients and during the course of recovery. The study is designed to test the overall hypothesis that following a stroke there is a window of enhanced neuroplasticity, leading to reorganization of the neural connectivity between the hemispheres that affects neural coupling. This again seems to be associated with the recovery of hand function.

The significance of the project is based on the assumption that the presence of neural coupling is related i) to the clinical impairment of hand function and, ii) to the site and size of affected brain areas reflected in magnetic resonance measurements. This allows us to use the neural coupling as an early marker to predict outcome of hand function. By such an approach rehabilitation goals can be defined together with the patients and his/her priorities in activities of daily living (ADL).

The significance and novelty of this project lies in the function and behavior of neural coupling early after a stroke. This mechanism coordinates hand movements in an optimal way and its presence is associated with the outcome of function. The recovery of hand function after stroke determines whether a patient will become able to perform bilateral hand movements for ADL. Therefore, its presence, plays an essential role in the prediction whether post-stroke subjects can remain self-independent.