Understanding the link between somatosensory temporal discrimination and movement execution in healthy subjects

• Published in: Physiological reports Vol. 4; no. 18; pp. np - n/a
• Main Authors: Conte, Antonella, Belvisi, Daniele, Manzo, Nicoletta, Bologna, Matteo, Barone, Francesca, Tartaglia, Matteo, Upadhyay, Neeraj, Berardelli, Alfredo
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.09.2016; John Wiley and Sons Inc
• Subjects: Achievement tests; Adult; Biomechanical Phenomena; Cortex (somatosensory); Cortex (temporal); Electrical stimuli; Excitability; Female; Finger; Hand - physiology; Healthy Volunteers; Humans; Kinematics; Magnetic fields; Male; Mental task performance; Motor Control; Movement; Movement execution; Original Research; Physiology; sensory gating; Sensory Neuroscience; sensory temporal discrimination; Somatosensory Cortex - physiology; Temporal discrimination; Temporal perception; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - methods; Italy; Movement execution; sensory gating; sensory temporal discrimination
• DOI: 10.14814/phy2.12899
• ISSN: 2051-817X

The somatosensory temporal discrimination threshold (STDT) is the shortest interval at which an individual recognizes paired stimuli as separate in time. We investigated whether and how voluntary movement modulates STDT in healthy subjects. In 17 healthy participants, we tested STDT during voluntary index‐finger abductions at several time‐points after movement onset and during motor preparation. We then tested whether voluntary movement‐induced STDT changes were specific for the body segment moved, depended on movement kinematics, on the type of movement or on the intensity for delivering paired electrical stimuli for STDT. To understand the mechanisms underlying STDT modulation, we also tested STDT during motor imagery and after delivering repetitive transcranial magnetic stimulation to elicit excitability changes in the primary somatosensory cortex (S1). When tested on the moving hand at movement onset and up to 200 msec thereafter, STDT values increased from baseline, but during motor preparation remained unchanged. STDT values changed significantly during fast and slow index‐finger movements and also, though less, during passive index‐finger abductions, whereas during tonic index‐finger abductions they remained unchanged. STDT also remained unchanged when tested in body parts other than those engaged in movement and during imagined movement. Nor did testing STDT at increased intensity influence movement‐induced STDT changes. The cTBS‐induced S1 cortical changes left movement‐induced STDT changes unaffected. Our findings suggest that movement execution in healthy subjects may alter STDT processing. The human brain relies fundamentally on interdependent sensory and motor networks. Sensory‐motor interplay depends essentially on temporal sensory information processing. Temporal sensory processing is impaired in patients with basal ganglia disorders (Parkinson's disease and dystonia). Precisely what these altered somatosensory temporal discrimination threshold (STDT) values imply in movement disorders remains unclear. In healthy subjects movement execution gates STDT processing at movement onset and up to 200 msec thereafter possibly through subcortical sensory gating mechanisms.