Cortical Effects of Peripheral Proprioceptive Stimulation on the Motor Evoked Potentials of the Limbs

Overview

Through motor muscle potentials, we will observe how a peripheral somatosensory mechanical stimulus on key limb musculature communicates signals via afferent sensory fibers that encode proprioceptive signals from muscle spindles (particularly type Ia fibers) to the somatosensory cortex at rest, confirming the integrative hypothesis of movement. These results would support interventions aimed at addressing sensory deafferentation present in multiple health conditions related to movement disorders, where disuse or immobilization lead to changes in movement patterns and a decrease in neuronal activation in somatosensory cortex areas involved in constructing voluntary movement.

Objective: To evaluate whether a proprioceptive stimulus applied to the limb of healthy subjects activates the corticospinal pathway, compared to a condition without stimulation, through the analysis of motor evoked potentials (MEPs). Methods: Experimental and crossover. Each participant will serve as their own control and will be assessed under both stimulation (experimental) and no-stimulation (control) conditions.The stimulus will consist of intermittent mechanical pressure on the skin located at the neuromuscular motor points (NMPs) of the upper limb (biceps muscle (B) and wrist extensors (WE)) and the lower limb (rectus femoris of the quadriceps (RFQ) and tibialis anterior (TA).Motor evoked potentials (MEPs) will be recorded from the B, WE, RFQ, and TA muscles using transcranial magnetic stimulation (TMS).The optimal stimulation point (hotspot-the area where TMS generates the highest MEP) will be identified individually for the B, WE, RFQ, and TA muscles.Participants will be recruited at the facilities of the Faculty of Physiotherapy and Nursing of Castilla-La Mancha University (UCLM), in collaboration with the Toledo Physiotherapy Research Group (GIFTO) and the Faculty of Health Sciences, Blanquerna - Ramon Llull University.