Finisguerra, A. | bioRxiv Science

bioRxiv2024

Investigating the effects of transcutaneous Vagus Nerve Stimulation on motor cortex excitability and inhibition through paired-pulse Transcranial Magnetic Stimulation

Transcutaneous Vagus Nerve stimulation (tVNS) has been proposed as a prospective treatment for clinical conditions with altered GABAergic transmission. While possible effects of tVNS on behavioral performance in inhibitory control tasks have been previously reported, neurophysiological evidence showing its effects on GABA-mediated inhibition in the motor cortex is limited. Concurrently, the possible influence of participants gender and state conditions remains unexplored. Here, we applied, single- and paired-pulse TMS to the right or the left primary motor in two different groups of participants. We measured corticospinal excitability (CSE), short and long intracortical inhibition (SICI and LICI), cortical silent period (cSP) and intracortical facilitation (ICF) indexes. The measures were taken, in separated sessions of a within-subject design, at baseline prior to tVNS and after delivering active and sham tVNS in the Cymba conchae of the left ear. To exploit state dependent effects and assess the role of tVNS in motor learning, tVNS was applied, during the execution of a computerized visuomotor task. In the left TMS group, we observed better visuomotor performance during active than sham tVNS, regardless of participants gender. Interestingly, in both groups, we found a specific increase of SICI, which is mediated by GABAa activity, after active compared to sham-tVNS and baseline evaluations, which was specifically limited to female participants. No effects on CSE, ICF or GABAb-mediated intracortical inhibition indexes were observed. The results show specific effects of tVNS on motor learning and GABAa-mediated motor inhibition, providing supportive evidence for the application of tVNS as an alternative and coadjuvant treatment for disorders featured by altered inhibition mechanisms.

neuroscience↗

bioRxiv2021

Neuropsychological assessment and virtual reality training of social prediction in patients with cerebellar malformation

It has been proposed that impairments of the predictive function exerted by the cerebellum may account for social cognition deficits. Here, we integrated cerebellar functions in a predictive coding framework to elucidate how cerebellar alterations could affect the predictive processing of others behavior. Experiment 1 demonstrated that cerebellar patients were impaired in relying on contextual information during action prediction, and this impairment was significantly associated with social cognition abilities. Experiment 2 indicated that patients with cerebellar malformation showed a domain-general deficit in using contextual information to predict both social and physical events. Experiment 3 provided first evidence that a social-prediction training in virtual reality could boost the ability to use context-based predictions to understand others intentions. These findings shed new light on the predictive role of the cerebellum and its contribution to social cognition, paving the way for new approaches to the rehabilitation of the Cerebellar Cognitive Affective Syndrome.

neuroscience↗