Search results for " Motor Cortex"

The effect of paired associative stimulation on fatigue resistance

2015

Paired associative stimulation (PAS) is a non-invasive stimulation method developed to induce bidirectional changes in the excitability of the cortical projections to the target muscles. However, very few studies have shown an association between changes in motor evoked potentials (MEP) after PAS and behavioral changes in healthy subjects. In the present study we hypothesized that the functional relevance of PAS can be seen during fatiguing exercise, since there is always a central contribution to the development of fatigue. Transcranial magnetic stimulation was applied over the motor cortex to measure changes in the MEPs of the soleus muscle before and after PAS. Furthermore, fatigue resis…

Functional MRI of human primary somatosensory and motor cortex during median nerve stimulation.

1999

Abstract Objectives: Somatosensory evoked potential (SEP) studies suggested that some early cortical SEP components may be generated in the primary motor cortex (M1) rather than the primary somatosensory cortex (S1). Methods: We now used functional magnetic resonance imaging (fMRI) to study activation of S1 and M1 by electrical median nerve stimulation in healthy volunteers. Results: The hand areas of both S1 and M1 showed significant activation (correlation coefficients >0.45) in 7 of 9 subjects (activated volume S1>M1). For comparison, a sequential finger opposition task significantly activated S1 in 7 and M1 in all 9 subjects (activated volume M1>S1). Conclusions: These data show that th…

Sympathetic activity at rest and motor brain areas: FDG-PET study.

2008

Although recent studies identified brain areas which are involved in short term activation of the sympathetic nervous system, little is known about brain mechanisms which generate the individual variability of basal autonomic activity. In this fluorodeoxyglucose positron emission tomography study (FDG-PET), we aimed to identify brain regions, which covary with function parameters of the autonomic nervous system at rest. Therefore, FDG-PET (Siemens, Germany) was performed twice in 14 healthy resting subjects (7 m, 7 f; mean age 29.5 years) while different parameters of autonomic function were assessed simultaneously: Blood pressure, heart rate, power spectra of heart rate variability (HF/LF …

Cerebellar magnetic stimulation decreases levodopa-induced dyskinesias in Parkinson disease

2009

BACKGROUND: The neural mechanisms and the circuitry involved in levodopa-induced dyskinesia (LID) are still partially obscure. LID can be considered the consequence of an abnormal pattern or code of activity that originates and is conveyed from the basal ganglia to the thalamus and the cortical motor areas. However, not only striatothalamocortical motor circuits but also other interconnected pathways could be implicated in its pathogenesis. METHODS: In a series of experiments, we applied repetitive transcranial magnetic stimulation (rTMS) over the lateral cerebellum in a group of patients with advanced Parkinson disease, to investigate whether modulation of cerebellothalamocortical circuits…

2021

Dystonia, a debilitating neurological movement disorder, is characterized by involuntary muscle contractions and develops from a complex pathophysiology. Graph theoretical analysis approaches have been employed to investigate functional network changes in patients with different forms of dystonia. In this study, we aimed to characterize the abnormal brain connectivity underlying writer's cramp, a focal hand dystonia. To this end, we examined functional magnetic resonance scans of 20 writer's cramp patients (11 females/nine males) and 26 healthy controls (10 females/16 males) performing a sequential finger tapping task with their non-dominant (and for patients non-dystonic) hand. Functional …

Functional electrical therapy for hemiparesis alleviates disability and enhances neuroplasticity

2011

Impaired motor and sensory function is common in the upper limb in humans after cerebrovascular stroke and it often remains as a permanent disability. Functional electrical stimulation therapy is known to enhance the motor function of the paretic hand; however, the mechanism of this enhancement is not known. We studied whether neural plasticity has a role in this therapy-induced enhancement of the hand motor function in 20 hemiparetic subjects with chronic stroke (age 53 ± 6 years; 7 females and 13 males; 10 with cerebral infarction and 10 with cerebral haemorrhage; and time since incident 2.4 ± 2.0 years). These subjects were randomized to functional electrical therapy or conventional phys…

Changes in intracortical circuits of the human motor cortex following theta burst stimulation of the lateral cerebellum

2008

Objective: The cerebellum takes part in several motor functions through its influence on the motor cortex (M1). Here, we applied the theta burst stimulation (TBS) protocol, a novel form of repetitive Transcranial Magnetic Stimulation (rTMS) over the lateral cerebellum. The aim of this study was to test whether TBS of the lateral cerebellum could be able to modulate the excitability of the contralateral M1 in healthy subjects. Methods: Motor-evoked potentials (MEPs) amplitude, short intracortical inhibition (SICI), long intracortical inhibition (LICI) and short intracortical facilitation (SICF) were tested in the M1 before and after cerebellar continuous TBS (cTBS) or intermittent TBS (iTBS)…

Transient topographical amnesia and cingulate cortex damage: A case report

1996

Transient topographical amnesia (TTA) is the temporary inability to find one's way in familiar or unfamiliar surroundings due to the inability to use well known environmental landmarks for route finding. The syndrome has not been described as having any obvious aetiology and has been thought to be caused by a vascular deficit in right hemispheric structures which are crucial for topographic recognition, i.e. parietal association and parahippocampal cortex. The patient described in the present study complained of several critical episodes of TTA and tonic rigidity of the left limbs. Neuropsychological assessment was normal except for a deficit in spatial memory tasks. Magnetic resonance (MR)…

rTMS of supplementary motor area modulates therapy-induced dyskinesias in Parkinson disease

2005

The neural mechanisms and circuitry involved in levodopa-induced dyskinesia are unclear. Using repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA) in a group of patients with advanced Parkinson disease, the authors investigated whether modulation of SMA excitability may result in a modification of a dyskinetic state induced by continuous apomorphine infusion. rTMS at 1 Hz was observed to markedly reduce drug-induced dyskinesias, whereas 5-Hz rTMS induced a slight but not significant increase.

Comparing MEG and EEG in detecting the ~20-Hz rhythm modulation to tactile and proprioceptive stimulation

2020

Abstract Modulation of the ~20-Hz brain rhythm has been used to evaluate the functional state of the sensorimotor cortex both in healthy subjects and patients, such as stroke patients. The ~20-Hz brain rhythm can be detected by both magnetoencephalography (MEG) and electroencephalography (EEG), but the comparability of these methods has not been evaluated. Here, we compare these two methods in the evaluating of ~20-Hz activity modulation to somatosensory stimuli. Rhythmic ~20-Hz activity during separate tactile and proprioceptive stimulation of the right and left index finger was recorded simultaneously with MEG and EEG in twenty-four healthy participants. Both tactile and proprioceptive st…