Search results for " Motor Cortex"

Effects of low-gamma tACS on primary motor cortex in implicit motor learning

2019

Abstract In the primary motor cortex (M1), rhythmic activity in the gamma frequency band has been found during movement planning, onset and execution. Although the role of high-gamma oscillatory activity in M1 is well established, the contribution of low-gamma activity is still unexplored. In this study, transcranial alternating current stimulation (tACS) was used with the aim to specifically modulate low-gamma frequency band in M1, during an implicit motor learning task. A 40 Hz-tACS was applied over the left M1 while participants performed a serial reaction time task (SRTT) using their right hand. The task required the repetitive execution of sequential movements in response to sequences …

Functional Role of Cerebellar Gamma Frequency in Motor Sequences Learning: a tACS Study

2021

Although the role of the cerebellum in motor sequences learning is widely established, the specific function of its gamma oscillatory activity still remains unclear. In the present study, gamma (50 Hz)—or delta (1 Hz)—transcranial alternating current stimulation (tACS) was applied to the right cerebellar cortex while participants performed an implicit serial reaction time task (SRTT) with their right hand. The task required the execution of motor sequences simultaneously with the presentation of a series of visual stimuli. The same sequence was repeated across multiple task blocks (from blocks 2 to 5 and from blocks 7 to 8), whereas in other blocks, new/pseudorandom sequences were reproduce…

SHORT-TERM SYNAPTIC PLASTICITY IN MIGRAINE MOTOR CORTEX: EVIDENCE BY PRECONDITIONING OF HIGH-FREQUENCY REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION (…

2011

Background: Brief 5Hz repetitive transcranial magnetic stimulation (rTMS) trains at 120% of the resting- motorthreshold (RMT) intensity determine in healthy subjects a potentiation of motor evoked potentials (MEPs), likely due to short-term presynaptic plasticity facilitation. We recently showed paradoxical intensity-dependent MEP changes to 5Hz rTMS in migraine with MEP facilitation at 110% and inhibition at 130% RMT. This provides evidence of both hyper-responsivity and self-limiting hyperexcitability capacity in migraine, likely due to earlier activation of inhibitory homeostatic plasticity mechanisms. To explore this, we applied in migraineurs cathodal transcranial Direct Current Stimul…

Prismatic Adaptation as a new tool for non-invasive brain modulation: evidence from different neurophysiological techniques.

Neuromodulation of chronic headaches: position statement from the European Headache Federation

2013

The medical treatment of patients with chronic primary headache syndromes (chronic migraine, chronic tension-type headache, chronic cluster headache, hemicrania continua) is challenging as serious side effects frequently complicate the course of medical treatment and some patients may be even medically intractable. When a definitive lack of responsiveness to conservative treatments is ascertained and medication overuse headache is excluded, neuromodulation options can be considered in selected cases.Here, the various invasive and non-invasive approaches, such as hypothalamic deep brain stimulation, occipital nerve stimulation, stimulation of sphenopalatine ganglion, cervical spinal cord sti…

P 56 tDCS shows no effects on motor cortex excitability at rest

2017

Introduction Transcranial direct current stimulation (tDCS) is a widely used technique in research and clinics. However, the underlying physiological mechanisms are not yet clear. Modeling studies suggest that the electric field during tDCS is dominated by a tangential component which predominantly modifies active synaptic connections ( Radman et al., 2007 ). We have previously shown that tDCS with an increased tangential compared to the conventional montage introduced by Nitsche and Paulus (2000) , suppresses the effects of paired associative stimulation of the supplementary motor area and the primary motor cortex (PASSMA-M1) independent of tDCS polarity (Faber et al., under submission). H…

Modulation of cortical motor outputs by the symbolic meaning of visual stimuli

2010

The observation of an action modulates motor cortical outputs in specific ways, in part through mediation of the mirror neuron system. Sometimes we infer a meaning to an observed action based on integration of the actual percept with memories. Here, we conducted a series of experiments in healthy adults to investigate whether such inferred meanings can also modulate motor cortical outputs in specific ways. We show that brief observation of a neutral stimulus mimicking a hand does not significantly modulate motor cortical excitability (Study 1) although, after prolonged exposure, it can lead to a relatively nonspecific modulation (Study 2). However, when such a neutral stimulus is preceded b…

Suppression of extinction with TMS in humans: from healthy controls to patients.

2006

We review a series of studies exemplifying some applications of single-pulse and paired-transcranial magnetic stimulation (TMS) in the study of spatial attention and of its deficits. We will focus primarily on sensory extinction, the failure to consciously perceive a contralesional sensory stimulus only during bilateral stimulation of homologous surfaces. TMS studies in healthy controls show that it is possible either to interfere or modulate the excitability of the parietal cortex during sensory (i.e. tactile and visual) attentional tasks, thus reproducing a condition of virtual extinction. TMS studies in patients with unilateral (mainly right) brain damage show that the modulation of the …

Adaptive Whisking in Mice

2021

Rodents generate rhythmic whisking movements to explore their environment. Whisking trajectories, for one, appear as a fixed pattern of whisk cycles at 5-10 Hz driven by a brain stem central pattern generator. In contrast, whisking behavior is thought to be versatile and adaptable to behavioral goals. To begin to systematically investigate such behavioral adaptation, we established a whisking task, in which mice altered the trajectories of whisking in a goal-oriented fashion to gain rewards. Mice were trained to set the whisker to a defined starting position and generate a protraction movement across a virtual target (no touch-related tactile feedback). By ramping up target distance based o…

Transcranial direct current stimulation for treatment of freezing of gait: A cross-over study

2014

Background and objective Progression of Parkinson's disease (PD) is frequently characterized by the occurrence of freezing of gait (FOG) representing a disabling motor complication. We aim to investigate safety and efficacy of transcranial direct current stimulation of the primary motor cortex of PD patients with FOG. Methods In this cross-over, double-blind, sham-controlled study, 10 PD patients with FOG persisting in “on” state underwent anodal and sham direct current stimulation for 5 consecutive days. Clinical assessment over a 1-month period was performed. Results A significant improvement of gait, as assessed by the Stand Walk Sit test, with reduction in number and duration of FOG epi…