An experimental analysis regarding neural bases of hand synergies during reach-to-grasp movements

Sammanfattning: Traumatic brain injury and diseases causing cortical damage is a global problem. Despite their vast extent, their pathophysiology is poorly understood. It is however known that the loss of motor functions can be regained thanks to adaptive properties of the neuronal system. Early task specific motor training is proven to be critical for rehabilitation. We set out to better understand how the CNS controls hand movement to in the future be able to access optimal diagnosis and motor training succeeding cortical damage. The approach, being to reach experimental support to the theory that muscle synergies during reach-to-grasp type movements are mirrored by synergies in cortical activity, was put into effect with the use of a tracking device for hand movement called Leap Motion, and an EEG system. Simultaneous recordings from these two systems were made on subjects to document angles of the hand as well as EEG signals in the cortex during approximately 100 repeats of four different types of carefully designed reach-to-grasp movements. Correlations between specific angles of the hand during the movements were calculated and plotted, as well as correlations between all electrodes. PCA was performed on both data sets to evaluate the possibility of dimensionality reduction. The results revealed groups with similar correlation patterns in both angular and EEG data, as well as primary principal components with high eigenvalues for both data sets, supporting the documented notion of muscular synergies as well as the theory of synergistic behaviour in the CNS.