Contents I. Introduction
The sensorimotor system in the brain is an integrated system where the sensory and motor circuits interact with each other during movement control. The sensorimotor system can undergo reorganization following an injury to the brain, during the recovery process. Previous studies focused on the pathological motor control in hemiparetic stroke have revealed functional and structural changes to motor pathways from the brain to the muscles, showing an increased reliance on contralesional cortico–bulbospinal pathways (which is ipsilateral to the paretic limb) [1]–[5]. However, it is unknown whether a similar hemispheric shift occurs in the sensory system to adapt to this motor pathway change and how sensory feedback would shift to the contralesional hemisphere to support such the use of contralesional motor pathways in hemiparetic stroke [1], [2], [6]. Recent studies in our group have shown increased recruitment of contralesional sensory cortical regions when stroke participants were passively receiving tactile stimulations to their fingers of the paretic arm [7], [8]. Similarly, enhanced resting-state interhemispheric connectivity of the primary sensory cortex has been previously reported to be associated with motor impairment after stroke [9]. Since no movement task was involved in these previous studies (either only passively receiving sensory input or at rest), it is still not clear whether the reported increase of sensory cortical activity at the contralesional hemisphere of the brain is associated with pathological motor control post-stroke.
