Reorganization of effective connectivity in the motor system after stroke

Background: Functional neuroimaging studies frequently demonstrated that stroke patients show bilateral activity in motor and premotor areas during movements of the paretic hand rather than the contralateral pattern seen in healthy subjects (1). A recent study applying effective connectivity analyses by dynamic causal modelling (DCM) to fMRI data of patients with chronic impairments found reduced connectivity within the ipsilesional motor network as well as a disturbed interhemispheric communication. Furthermore, there was an enhanced inhibition from contralesional to ipsilesional primary motor cortex (M1) (2).…