The purpose of this study is to investigate the effects of transcranial magnetic stimulation (TMS) on motor cortex excitability in individuals who have suffered stroke and to study the influence of the phase of the oscillatory rhythm (mu frequency) on motor excitability in stroke individuals.
Neurological disorders, including stroke, are associated with impaired movement leading to significant negative effects on quality of life. Transcranial magnetic stimulation (TMS) is increasingly being explored as a rehabilitation strategy to enhance plasticity in motor regions. However, it is not yet fully understood how TMS acts on motor circuits and what optimal stimulation parameters are. TMS is a noninvasive neuromodulation method which enables in vivo perturbation of neural activity in humans through the application of electromagnetic fields to the brain. TMS has an established safety profile and has been explored extensively in clinical trials for a range of neurological and psychiatric disorders. Particularly, in potential positive effects of TMS have been identified for stroke rehabilitation. However, significant variability in treatment outcomes across patients has been found, making it necessary to improve current stimulation protocols and to investigate basic mechanism of action . The investigators plan to study the effects of TMS to the motor cortex in individuals who suffered stroke for movement rehabilitation. The investigators plan to measure motor evoked potentials (MEPs) at different phases of the motor mu-rhythm measured with EEG. Mu rhythms are related to healthy movement execution. By this, the investigators characterize phase-dependent cortical excitability differences in stroke.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
24
TMS will be administrated with a Magstim 70mm figure-8 coil allowing for focal stimulation. Single-pulse TMS will be applied at different phases, (0, 90, 180, 270 degrees - 4 stimulation conditions), of the ongoing mu-rhythm. Positioning of the TMS coil will be neuronavigated based on individual MRI scans. Stimulation will be applied in a closed-loop fashion while the participant is at rest and their EEG activity is recorded.
University of Minnesota
Minneapolis, Minnesota, United States
Normalized Motor Evoked Potential Amplitude by Mu-Rhythm Phase(MEPs)
Motor evoked potential amplitude was recorded from the first dorsal interosseous muscle by electromyography during EEG-guided phase-targeted single-pulse transcranial magnetic stimulation. Motor evoked potentials were measured at four phases of the ongoing mu rhythm: peak, falling phase, trough, and rising phase. Values are reported as normalized millivolts, with higher values indicating greater motor cortex excitability.
Time frame: During the second experimental TMS-EEG session, up to 3 hours
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