Search results for "motor cortex"
showing 10 items of 244 documents
Treatment of pemphigus vulgaris with mycophenolate mofetil
1997
different pattern of diffusion changes in a 51-year-old woman with chronic epilepsy and recurrent episodes of focal status epilepticus, for whom no aetiology could be established. Status consisted of clonic jerking of the right leg, which continued for 22 days and was followed by transient paresis. DWI during status showed decreased diffusion in the motor cortex of the right leg (relative decrease in ADC of 27%, see figure). Surprisingly, the diffusion was increased in the subcortical white matter (relative increase in ADC of 31%). On the T2-weighted image (not shown), both cortex and subcortical white matter of the corresponding region returned a high signal similar to previously reported …
TMS activation of interhemispheric pathways between the posterior parietal cortex and the contralateral motor cortex
2009
Using a twin coil transcranial magnetic stimulation (tc-TMS) approach we have previously demonstrated that facilitation may be detected in the primary motor cortex (M1) following stimulation over the ipsilateral caudal intraparietal sulcus (cIPS). Here we tested the interhemispheric interactions between the IPS and the contralateral motor cortex (M1). We found that conditioning the right cIPS facilitated contralateral M1 when the conditioning stimulus had an intensity of 90% resting motor threshold (RMT) but not at 70% or 110% RMT. Facilitation was maximal when the interstimulus interval (ISI) between cIPS and M1 was 6 or 12 ms. These facilitatory effects were mediated by interactions with …
Grasp-specific motor resonance is influenced by the visibility of the observed actor
2016
AbstractMotor resonance is the modulation of M1 corticospinal excitability induced by observation of others' actions. Recent brain imaging studies have revealed that viewing videos of grasping actions led to a differential activation of the ventral premotor cortex depending on whether the entire person is viewed versus only their disembodied hand. Here we used transcranial magnetic stimulation (TMS) to examine motor evoked potentials (MEPs) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) during observation of videos or static images in which a whole person or merely the hand was seen reaching and grasping a peanut (precision grip) or an apple (whole hand grasp). Part…
Relationship between physiological excitatory and inhibitory measures of excitability in the left vs. right human motor cortex and peripheral electro…
2017
Abstract The current study was aimed at investigating the relationships of excitatory and inhibitory circuits of the left vs. right primary motor cortex with peripheral electrodermal activity (EDA). Ten healthy subjects participated in two experimental sessions. In each session, EDA was recorded for 10 min from the palmar surface of the left hand. Immediately after EDA recording, Transcranial Magnetic Stimulation (TMS) was used to probe excitatory and inhibitory circuits of the left or right primary motor cortex using two protocols of stimulation: the input-output curve for recording of motor evoked potentials, for testing excitatory circuits; the long-interval cortical inhibition (LICI) pr…
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 …
The role of the dorsolateral prefrontal cortex in implicit procedural learning.
1996
We studied the role of the dorsolateral prefrontal cortex in procedural learning. Normal subjects completed several blocks of a serial reaction time task using only one hand without or with concurrent non-invasive repetitive transcranial magnetic stimulation. To disrupt their function transiently, stimulation was applied at low intensity over the supplementary motor area or over the dorsolateral prefrontal cortex contralateral or ipsilateral to the hand used for the test. Stimulation to the contralateral dorsolateral prefrontal cortex markedly impaired procedural implicit learning, as documented by the lack of significant change in response times during the task. Stimulation over the other …
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…
Transcranial magnetic stimulation and neuroplasticity
1998
We review past results and present novel data to illustrate different ways in which TMS can be used to study neural plasticity. Procedural learning during the serial reaction time task (SRTT) is used as a model of neural plasticity to illustrate the applications of TMS. These different applications of TMS represent principles of use that we believe are applicable to studies of cognitive neuroscience in general and exemplify the great potential of TMS in the study of brain and behavior. We review the use of TMS for (1) cortical output mapping using focal, single-pulse TMS; (2) identification of the mechanisms underlying neuroplasticity using paired-pulse TMS techniques; (3) enhancement of th…
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…