Interazione tra cTBS cerebellare e movimenti volontari semplici e complessi dell'arto superiore : nuove acquisizioni sui processi di plasticità omeostati e di formazione della memoria motoria

The aim of the present study was to investigate in healthy subjects whether continuous theta-burst stimulation (cTBS) applied over the lateral cerebellum alters motor learning (acquisition and retention phases) during ipsilateral simple and complex movements. Eighteen healthy subjects participated in the study. We delivered cTBS over the lateral cerebellum immediately before a motor learning task involving repeated simple (i.e. index finger-abductions) and complex (i.e. reaching) movements. As motor learning measures we evaluated kinematic variables for simple and complex movements during the task. To see whether cerebellar cTBS-induced changes in motor learning take place through changes in primary motor cortex (M1) activity we used single-pulse transcranial magnetic stimulation (TMS) and evaluated changes in motor evoked potential (MEP) amplitude throughout the experiment. Cerebellar cTBS left the practice-related increase in peak acceleration unchanged but decreased peak acceleration for index finger and reaching movements during motor retention. The smoothness and straightness for trajectories related to reaching movements remained unchanged. When subjects repeated simple and complex movements performed alone, M1 excitability, as measured by the TMS-induced MEP facilitation, increased and MEP amplitudes increased more during simple movements than during complex movements. Cerebellar cTBS given before simple and complex movement tasks decreased the MEP facilitation induced by simple movements, whereas it increased the MEP facilitation induced by complex movements. During simple and complex movement tasks testing motor learning, no matter how complicated the motor task, cerebellar cTBS interferes with motor memory formation. cTBS induces changes in cerebellar activity thus altering motor-learning-related synaptic activity in M1

Interazione tra cTBS cerebellare e movimenti volontari semplici e complessi dell'arto superiore : nuove acquisizioni sui processi di plasticità omeostati e di formazione della memoria motoria

The aim of the present study was to investigate in healthy subjects whether continuous theta-burst stimulation (cTBS) applied over the lateral cerebellum alters motor learning (acquisition and retention phases) during ipsilateral simple and complex movements. Eighteen healthy subjects participated in the study. We delivered cTBS over the lateral cerebellum immediately before a motor learning task involving repeated simple (i.e. index finger-abductions) and complex (i.e. reaching) movements. As motor learning measures we evaluated kinematic variables for simple and complex movements during the task. To see whether cerebellar cTBS-induced changes in motor learning take place through changes in primary motor cortex (M1) activity we used single-pulse transcranial magnetic stimulation (TMS) and evaluated changes in motor evoked potential (MEP) amplitude throughout the experiment. Cerebellar cTBS left the practice-related increase in peak acceleration unchanged but decreased peak acceleration for index finger and reaching movements during motor retention. The smoothness and straightness for trajectories related to reaching movements remained unchanged. When subjects repeated simple and complex movements performed alone, M1 excitability, as measured by the TMS-induced MEP facilitation, increased and MEP amplitudes increased more during simple movements than during complex movements. Cerebellar cTBS given before simple and complex movement tasks decreased the MEP facilitation induced by simple movements, whereas it increased the MEP facilitation induced by complex movements. During simple and complex movement tasks testing motor learning, no matter how complicated the motor task, cerebellar cTBS interferes with motor memory formation. cTBS induces changes in cerebellar activity thus altering motor-learning-related synaptic activity in M1

Voluntary movement takes shape. the link between movement focusing and sensory input gating

The aim of the study was to investigate the relationship between motor surround inhibition (mSI) and the modulation of somatosensory temporal discrimination threshold (STDT) induced by voluntary movement. Seventeen healthy volunteers participated in the study. To assess mSI, we delivered transcranial magnetic stimulation (TMS) single pulses to record motor evoked potentials (MEPs) from the right abductor digiti minimi (ADM; “surround muscle”) during brief right little finger flexion. mSI was expressed as the ratio of ADM MEP amplitude during movement to MEP amplitude at rest. We preliminarily measured STDT values by assessing the shortest interval at which subjects were able to recognize a pair of electric stimuli, delivered over the volar surface of the right little finger, as separate in time. We then evaluated the STDT by using the same motor task used for mSI. mSI and STDT modulation were evaluated at the same time points during movement. mSI and STDT modulation displayed similar time-dependent changes during index finger movement. In both cases, the modulation was maximally present at the onset of the movement and gradually vanished over about 200 ms. Our study provides the first neurophysiological evidence about the relationship between mSI and tactile-motor integration during movement execution

Voluntary Movement Takes Shape: The Link Between Movement Focusing and Sensory Input Gating

The aim of the study was to investigate the relationship between motor surround inhibition (mSI) and the modulation of somatosensory temporal discrimination threshold (STDT) induced by voluntary movement. Seventeen healthy volunteers participated in the study. To assess mSI, we delivered transcranial magnetic stimulation (TMS) single pulses to record motor evoked potentials (MEPs) from the right abductor digiti minimi (ADM; “surround muscle”) during brief right little finger flexion. mSI was expressed as the ratio of ADM MEP amplitude during movement to MEP amplitude at rest. We preliminarily measured STDT values by assessing the shortest interval at which subjects were able to recognize a pair of electric stimuli, delivered over the volar surface of the right little finger, as separate in time. We then evaluated the STDT by using the same motor task used for mSI. mSI and STDT modulation were evaluated at the same time points during movement. mSI and STDT modulation displayed similar time-dependent changes during index finger movement. In both cases, the modulation was maximally present at the onset of the movement and gradually vanished over about 200 ms. Our study provides the first neurophysiological evidence about the relationship between mSI and tactile-motor integration during movement execution

Towards a Muon Collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work.Comment: 118 pages, 103 figure

Towards a muon collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work

Erratum: Towards a muon collider

The original online version of this article was revised: The additional reference [139] has been added. Tao Han’s ORICD ID has been incorrectly assigned to Chengcheng Han and Chengcheng Han’s ORCID ID to Tao Han. Yang Ma’s ORCID ID has been incorrectly assigned to Lianliang Ma, and Lianliang Ma’s ORCID ID to Yang Ma. The original article has been corrected

Towards a muon collider

A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work

Early visuomotor integration processes induce LTP/LTD-like plasticity in the human motor cortex

To investigate whether visuomotor integration processes induce long-term potentiation (LTP) and depression (LTD)-like plasticity in the primary motor cortex (M1), we designed a new paired associative stimulation (PAS) protocol coupling left primary visual area (V1) activation achieved by hemifield visual evoked potentials (VEPs) and transcranial magnetic stimulation (TMS) over the left M1, at specific interstimulus intervals (ISIs), delivered at 1 Hz (V-PAS). Before and after V-PAS, we measured motor evoked potentials (MEPs). To clarify the mechanisms underlying V-PAS, we tested the effect of 1-Hz repetitive TMS (rTMS), 0.25-Hz V-PAS and rTMS, and a shorter 0.25-Hz V-PAS protocol. To examine V-PAS with contralateral V1 activation, we delivered V-PAS activating the right V1. To clarify whether V-PAS increases V1 activity or parieto- and premotor-to-M1 connectivity, before and after V-PAS, we examined VEPs and MEPs evoked by paired-pulse techniques. V-PAS increased, decreased, or left MEPs unchanged according to the ISI used. After 1-Hz rTMS MEPs decreased. Although 0.25-Hz rTMS elicited no aftereffect, 0.25-Hz V-PAS modulated MEPs according to the ISI used. The short 0.25-Hz V-PAS protocol left MEPs unchanged. Contralateral V-PAS inhibited MEPs. After V-PAS, VEPs remained unchanged and the premotor-to-M1 inhibitory connections decreased. V-PAS induces M1 LTP/LTD-like plasticity by activating premotor-to-motor connections