Search results for "MAGNETIC STIMULATION"
showing 10 items of 293 documents
Which direction should I go? A quest for understanding the effect of TMS stimulus orientation on evoked responses
2023
The orientation of the electric field (E-field) induced by transcranial magnetic stimulation (TMS) plays a significant role in determining the magnitude of motor evoked potentials (MEP) and TMS-evoked potentials (TEP). However, fundamental mechanisms explaining the interaction of the induced E-field and the underlying neuronal populations are still largely unknown. We recently entered a quest to understand and describe neurophysiological and physical factors affecting the effect of the E-field orientation on the MEP and TEP. We developed a dual-coil TMS transducer capable of fast and accurate electronic control of the induced E-field orientation. With this transducer, we could scan the effe…
Beta Rebound as an Index of Temporal Integration of Somatosensory and Motor Signals
2020
Modulation of cortical beta rhythm (15-30 Hz) is present during preparation for and execution of voluntary movements as well as during somatosensory stimulation. A rebound in beta synchronization is observed after the end of voluntary movements as well as after somatosensory stimulation and is believed to describe the return to baseline of sensorimotor networks. However, the contribution of efferent and afferent signals to the beta rebound remains poorly understood. Here, we applied electrical median nerve stimulation (MNS) to the right side followed by transcranial magnetic stimulation (TMS) on the left primary motor cortex after either 15 or 25 ms. Because the afferent volley reaches the …
Intracranial measurement of current densities induced by transcranial magnetic stimulation in the human brain
2003
Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses the principle of electromagnetic induction to generate currents in the brain via pulsed magnetic fields. The magnitude of such induced currents is unknown. In this study we measured the TMS induced current densities in a patient with implanted depth electrodes for epilepsy monitoring. A maximum current density of 12 microA/cm2 was recorded at a depth of 1 cm from scalp surface with the optimum stimulation orientation used in the experiment and an intensity of 7% of the maximal stimulator output. During TMS we recorded relative current variations under different stimulating coil orientations and at different points…
Progression of adverse effects over consecutive sessions of transcranial direct current stimulation
2017
final draft
Motor and linguistic linking of space and time in the cerebellum
2009
Background: Recent literature documented the presence of spatial-temporal interactions in the human brain. The aim of the present study was to verify whether representation of past and future is also mapped onto spatial representations and whether the cerebellum may be a neural substrate for linking space and time in the linguistic domain. We asked whether processing of the tense of a verb is influenced by the space where response takes place and by the semantics of the verb. Principal Findings: Responses to past tense were facilitated in the left space while responses to future tense were facilitated in the right space. Repetitive transcranial magnetic stimulation (rTMS) of the right cereb…
Neurophysiological mechanisms of motor imagery : effects of associated somatosensory stimulation
2018
Mental training, which involves mentally simulating an action without motor output, is an effective stimulus to improve the maximal voluntary contraction. If only the motor pathway is activated, an activation of the somatosensory cortex is observed despite the lack of afferent feedback. Indeed, the motor imagery task efficiency is based in part on an interaction between motor and sensory pathway. Thus, it’s seems reasonable to think that the addition of sensory afferent feedback during motor imagery could potentiate the motor imagery effects and thus improve motor performance. In our first study, we showed that the addition of somatosensory stimulation of Ia-afferents during a motor imagery…
Concurrent TMS-fMRI for causal network perturbation and proof of target engagement
2021
The experimental manipulation of neural activity by neurostimulation techniques overcomes the inherent limitations of correlative recordings, enabling the researcher to investigate causal brain-behavior relationships. But only when stimulation and recordings are combined, the direct impact of the stimulation on neural activity can be evaluated. In humans, this can be achieved non-invasively through the concurrent combination of transcranial magnetic stimulation (TMS) with functional magnetic resonance imaging (fMRI). Concurrent TMS-fMRI allows the assessment of the neurovascular responses evoked by TMS with excellent spatial resolution and full-brain coverage. This enables the functional ma…
Measuring network disruption in neurodegenerative diseases: New approaches using signal analysis
2019
Advanced neuroimaging has increased understanding of the pathogenesis and spread of disease, and offered new therapeutic targets. MRI and positron emission tomography have shown that neurodegenerative diseases including Alzheimer’s disease (AD), Lewy body dementia (LBD), Parkinson’s disease (PD), frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) are associated with changes in brain networks. However, the underlying neurophysiological pathways driving pathological processes are poorly defined. The gap between what imaging can discern and underlying pathophysiology can now be addressed by advanced techniques that explore the cortical neural synchro…
Insights About the Neuroplasticity State on the Effect of Intramuscular Electrical Stimulation in Pain and Disability Associated With Chronic Myofasc…
2018
Background: There is limited evidence concerning the effect of intramuscular electrical stimulation (EIMS) on the neural mechanisms of pain and disability associated with chronic Myofascial Pain Syndrome (MPS). Objectives: To provide new insights into the EIMS long-term effect on pain and disability related to chronic MPS (primary outcomes). To assess if the neuroplasticity state at baseline could predict the long-term impact of EIMS on disability due to MPS we examined the relationship between the serum brain-derived-neurotrophic-factor (BDNF) and by motor evoked potential (MEP). Also, we evaluated if the EIMS could improve the descending pain modulatory system (DPMS) and the cortical exci…
Study of molecular mechanism involved in neuronal plasticity induced by magnetic stimulation in cultured hippocampal neurons
2014
Although a large number of investigations have shown that transcranial magnetic stimulation, a non-invasive method of brain stimulation with minimal side effects, is able to induce neuronal synaptic plastic change, very few studies have examined the molecular mechanisms of magnetic stimulation involved in synaptic plasticity. Since it is well known that neurotrophins and their receptors regulate synaptic strength and thereby mediate plasticity, in this study we have investigated the effects of low-frequency (1 Hz) magnetic stimulation, at different intensities, on the activation of neurotrophic factors receptors and relative intracellular pathways in primary cultures of hippocampal neurons.…