Background: The ability to perceive two tactile stimuli as asynchronous can be measured using the somatosensory temporal discrimination threshold (STDT). In healthy humans, the execution of a voluntary movement determines an increase in STDT values, while the integration of STDT and movement execution is abnormal in patients with basal ganglia disorders. Sensorimotor integration can be modulated using focal muscle vibration (fMV), a neurophysiological approach that selectively activates proprioceptive afferents from the vibrated muscle. Method: In this study, we investigated whether fMV was able to modulate STDT or STDT-movement integration in healthy subjects by measuring them before, during and after fMV applied over the first dorsalis interosseous, abductor pollicis brevis and flexor radialis carpi muscles. Results: The results showed that fMV modulated STDT-movement integration only when applied over the first dorsalis interosseous, namely, the muscle performing the motor task involved in STDT-movement integration. These changes occurred during and up to 10 min after fMV. Differently, fMV did not influence STDT at rest. We suggest that that fMV interferes with the STDT-movement task processing, possibly disrupting the physiological processing of sensory information. Conclusions: This study showed that FMV is able to modulate STDT-movement integration when applied over the muscle involved in the motor task. This result provides further information on the mechanisms underlying fMV, and has potential future implications in basal ganglia disorders characterized by altered sensorimotor integration.
Keywords: focal muscle vibration; neuromodulation; sensorimotor integration.