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.

Background: Understanding the neural organization underlying motor function is essential for explaining individual differences in motor performance and the impact of aging. Methods: We examined 87 healthy older adults who underwent, in different sessions, resting state electroencephalography (EEG) recordings and Transcranial Magnetic Stimulation (TMS) applied to the hand muscles representation area in the primary motor cortex to elicit Motor Evoked Potentials (MEPs). Furthermore, Mini‐Mental State Examination (MMSE) and handgrip strength evaluations were carried out on subjects. Subjects were split into two groups, Low MEP (L‐MEP) and High MEP (H‐MEP) groups, based on individual MEP amplitude, and age, sex, and education matched. Functional connectivity was analyzed through Magnitude‐Squared Coherence (MSCoh) and Total Coherence (TotCoh) in different frequency bands and brain regions of interest. Findings: The L‐MEP presented decreased MSCoh in the Alpha 2 and Beta 1 bands, and decreased TotCoh in the Alpha 2 band within the Temporal region as well as in the Beta 1 band across Parietal, Occipital, and Temporal regions. No significant difference in grip strength was found while the MMSE score of L‐MEP group was significantly lower compared to the H‐MEP one. These findings indicate that reduced motor cortex excitability reflects decreased network integration, particularly in regions associated with cognitive and sensorimotor processing. These findings may reflect early neurophysiological vulnerability. Conclusions: These results underscore the resting state EEG as a non‐invasive, highly sensitive tool monitoring subtle alterations in brain functional networks that may precede clinical symptoms, offering a powerful tool for monitoring and individualized intervention.

Cerebellar paired associative stimulation (cPAS) is a non-invasive neuromodulation protocol that combines peripheral nerve stimulation with cerebellar transcranial magnetic stimulation to induce plasticity in the cerebellar-cortical pathway. Previous evidence suggested that cPAS delivered at a 25ms interstimulus interval (cPAS25) can modulate cerebellar-primary motor cortex connectivity, as reflected by changes in cerebellar–brain inhibition (CBI). However, its behavioural relevance remains unclear. To investigate this issue, we conducted two experiments in young healthy adults using a within-subject crossover design to compare the effects of cPAS25 and a temporally mismatched control (cPAS10). In Experiment 1, participants received cPAS followed by a visuomotor sequence learning task, with motor performance assessed via movement time, error rate, and a composite skill index. CBI and motor evoked potentials (MEPs) were recorded at baseline, post-stimulation, and after task completion. In Experiment 2, a subset of participants received cPAS without the task to isolate its neurophysiological effects. cPAS25 significantly improved motor learning compared to cPAS10, as shown by a greater increase in skill index. It also reduced CBI, but this effect was observed only when cPAS was not followed by motor practice, suggesting a task-sensitive interaction. MEP amplitudes remained unchanged, indicating selective modulation of cerebellar output. These results support a timing-dependent, context-sensitive mechanism of cerebellar plasticity. cPAS25 can enhance motor learning and modulate cerebellar–cortical connectivity, although effects may not summate when paired with motor practice. These findings highlight the translational potential of cPAS25 as a precision neuromodulatory approach to enhance motor learning and rehabilitation by targeting cerebellar circuits.

The present work investigated how aging influences the different stages of face expressions processing: fixation patterns, early perception, face motor response and recognition. Thirty-four participants (17 young, 17 senior) were subjected to i) recording of fixation patterns, ii) recording of the P100 and the N170 components of event-related potentials, iii) excitability of short intracortical inhibition (SICI) and intracortical facilitation (ICF) of the face primary motor cortex (face M1) , and iv) recognition task during the passive viewing of neutral, happy and sad faces expressions. senior subjects mostly looked at the mouth, had reduced pupil size and delayed N170 latency, regardless of expression, compared to young ones; and a reduced P100 amplitude when viewing sad faces. Senior subjects’ excitability of face M1 (was enhanced compared to the young group; both groups had a reduced SICI when viewing happy faces, but only senior subjects exhibited reduced SICI for sad faces. Young subjects had better recognition accuracy and response times than senior ones, particularly for sad expressions. When viewing sad expressions, SICI was negatively correlated with pupil size and recognition accuracy, and positively correlated with N170 latency. Data suggested that aging reduces visual attention for sad faces which appears to be connected to an increased excitability of face M1, which in turn is linked to their impaired recognition skills, especially when processing negative face expressions. These findings prove new insights in the comprehension of how aging affects cognitive functions and the process of face expressions recognition.