The Role of Hemispheric Sensory Shifts: Impacts on Stretch Reflex and Motor Plasticity Post-Stroke.

Previous studies have found that post-stroke motor impairments are associated with damage to the lesioned corticospinal tract and the hyperexcitability of the cortico-reticulospinal tract at the hemisphere opposite to the lesion side, i.e., the contralesional hemisphere. While motor deficits and recovery mechanisms have been extensively studied, the role of sensory feedback in motor control has received less attention. We hypothesize that sensory-motor reorganization influences the stretch reflex and contributes to post-stroke spasticity. Effective motor function depends on the sensorimotor network, which integrates proprioceptive, tactile, and vibratory sensory inputs to guide movement and facilitate sensorimotor plasticity. Following stroke, these sensory pathways may undergo significant reorganization, leading to disrupted feedback loops and maladaptive changes in motor pathways. Recent studies have reported a hemispheric shift of somatosensory processing following a stroke. We propose to test our hypothesis by quantitatively analyzing the extent to which reorganization of sensory feedback pathways affects the stretch reflex. Testing our hypothesis will provide novel insights into the pathophysiological mechanisms underlying post-stroke spasticity. This will facilitate the development of customized rehabilitation strategies tailored to individual patient needs including improving their sensory feedback during movement exercise and other therapeutical intervention.