scholarly journals Effect of Therapy on Motor Cortical Excitability in Parkinson’s Disease

2008 ◽  
Vol 35 (2) ◽  
pp. 166-172 ◽  
Author(s):  
Aysun Soysal ◽  
Ismail Sobe ◽  
Turan Atay ◽  
Aysu Sen ◽  
Baki Arpaci
Keyword(s):  
Parkinson’S Disease ◽  
Late Stage ◽  
Evoked Potential ◽  
Cortical Excitability ◽  
Early Stage ◽  
Motor Evoked Potential ◽  
Motor Threshold ◽  
Potential Amplitude ◽  
Motor Cortical Excitability ◽  
Motor Cortical

Objective:To assess the impact of the disease stage and therapy on motor cortical excitability in Parkinson’s disease (PD).Methods:Twenty newly diagnosed and medication-free, early stage patients, 20 late stage patients under antiparkinsonian therapy and 20 normal healthy controls were included. Motor threshold (MT), amplitudes of motor evoked potential (MEP), motor evoked potential amplitude/compound muscle action potential amplitude (MEP/CMAP) ratio, central motor conduction time (CMCT) and cortical silent period (CSP) were measured by stimulation of the motor cortex using a 13.5 cm circular coil and recordings from abductor digiti minimi muscle. Following the first study protocol, early stage patients were given therapy and the same protocol was repeated three months later.Results:Motor threshold was lower; and the MEP/CMAP ratio was higher in early and late stage patients than normals. In early stage patients after proper therapy, the MTs became higher than before therapy, but still remained lower than normals. In late stage patients, the CMCTs were shorter than the early stage patients before therapy and normals, but there was no difference between the early stage patients and normals. In early stage patients after therapy, the CMCT became longer than before therapy and this difference was significant in both late stage patients and normals. Although more prominent in late stage patients, the CSP duration in both PD groups was found shorter than normals. In early stage patients, after therapy, the CSP durations became significantly longer compared with before therapy.Conclusion:These findings suggest that the motor cortical excitability increases in PD because of the impairment of the corticomotoneuronal inhibitory system.

Low-intensity repetitive transcranial magnetic stimulation decreases motor cortical excitability in humans

2006 ◽  
Vol 101 (2) ◽  
pp. 500-505 ◽  
Author(s):  
Gabrielle Todd ◽  
Stanley C. Flavel ◽  
Michael C. Ridding
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Threshold ◽  
Sham Stimulation ◽  
Motor Cortical Excitability ◽  
Resting Motor Threshold ◽  
Active Motor ◽  
Motor Cortical

Repetitive transcranial magnetic stimulation of the motor cortex (rTMS) can be used to modify motor cortical excitability in human subjects. At stimulus intensities near to or above resting motor threshold, low-frequency rTMS (∼1 Hz) decreases motor cortical excitability, whereas high-frequency rTMS (5–20 Hz) can increase excitability. We investigated the effect of 10 min of intermittent rTMS on motor cortical excitability in normal subjects at two frequencies (2 or 6 Hz). Three low intensities of stimulation (70, 80, and 90% of active motor threshold) and sham stimulation were used. The number of stimuli were matched between conditions. Motor cortical excitability was investigated by measurement of the motor-evoked potential (MEP) evoked by single magnetic stimuli in the relaxed first dorsal interosseus muscle. The intensity of the single stimuli was set to evoke baseline MEPs of ∼1 mV in amplitude. Both 2- and 6-Hz stimulation, at 80% of active motor threshold, reduced the magnitude of MEPs for ∼30 min ( P < 0.05). MEPs returned to baseline values after a weak voluntary contraction. Stimulation at 70 and 90% of active motor threshold and sham stimulation did not induce a significant group effect on MEP magnitude. However, the intersubject response to rTMS at 90% of active motor threshold was highly variable, with some subjects showing significant MEP facilitation and others inhibition. These results suggest that, at low stimulus intensities, the intensity of stimulation may be as important as frequency in determining the effect of rTMS on motor cortical excitability.

Paired-pulse measures

2012 ◽  
Author(s):  
Ritsuko Hanajima ◽  
Yoshikazu Ugawa
Keyword(s):  
Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potential ◽  
Paired Pulse ◽  
Motor Cortical Excitability ◽  
Interhemispheric Connectivity ◽  
Conditioned Motor ◽  
Human Motor ◽  
Motor Cortical ◽  
Insight Into

This article reviews the physiology and application of the currently available paired-pulse protocols. Paired-pulse transcranial magnetic stimulation (TMS) techniques study the modulation of human motor cortical excitability. Paired-pulse experiments are designed to give insight into the nature of the cortical circuitry activated by TMS. Changes in motor cortical excitability produced by the conditioning pulse are estimated by changes in the size of the conditioned motor-evoked potential (MEP). It is possible to identify specific abnormalities in the balance between inhibitory and facilitatory processes, even if the pathology lies in abnormal afferent signalling to the motor cortex rather than in the motor cortex itself. The conclusion that emerges from the studies on interhemispheric interactions is that it is now possible by means of TMS protocols to chart long-range functional interhemispheric connectivity of remote areas of the human brain.

Interhemispheric asymmetry of motor cortical excitability in major depression as measured by transcranial magnetic stimulation

2000 ◽  
Vol 177 (2) ◽  
pp. 169-173 ◽  
Author(s):  
Fumiko Maeda ◽  
Julian P. Keenan ◽  
Alvaro Pascual-Leone
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Motor Threshold ◽  
Major Depressive ◽  
Paired Pulse ◽  
Prefrontal Cortical ◽  
Motor Cortical Excitability ◽  
Motor Cortical ◽  
Normal Controls

BackgroundNeuroimaging studies of major depressive disorder (MDD) indicate interhemispheric differences in prefrontal cortical activity (right greater than left).AimsTo investigate whether there are any interhemispheric differences of motor cortical excitability in MDD.MethodEight patients with treatment-refractory MDD off medication were assessed for the severity of their depression, and transcranial magnetic stimulation studies (bilateral motor threshold and paired-pulse studies) were conducted. Eight normal controls were also studied.ResultsMDD patients showed significant interhemispheric differences in motor threshold and paired-pulse curves, both of which showed lower excitability on the left hemisphere. Such differences were absent in controls.ConclusionsOur findings may aid the further understanding of the neurophysiology underlying MDD.

scholarly journals Air-puff-induced facilitation of motor cortical excitability studied in patients with discrete brain lesions

Brain ◽  
1999 ◽  
Vol 122 (12) ◽  
pp. 2259-2277 ◽  
Author(s):  
Yasuo Terao ◽  
Yoshikazu Ugawa ◽  
Ritsuko Hanajima ◽  
Toshiaki Furubayashi ◽  
Katsuyuki Machii ◽  
...  
Keyword(s):  
Cortical Excitability ◽  
Brain Lesions ◽  
Motor Cortical Excitability ◽  
Motor Cortical

scholarly journals A Short Bout of High-intensity Exercise Alters Ipsilesional Motor Cortical Excitability Post-stroke

2019 ◽  
Author(s):  
Xin Li ◽  
Charalambos C. Charalambous ◽  
Darcy S. Reisman ◽  
Susanne M. Morton
Keyword(s):  
High Intensity ◽  
Acute Exercise ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
High Intensity Exercise ◽  
Exercise Protocol ◽  
Post Stroke ◽  
Motor Cortical Excitability ◽  
Motor Cortical ◽  
Lactate Levels

AbstractBackgroundAcute exercise can increase motor cortical excitability and enhance motor learning in healthy individuals, an effect known as exercise priming. Whether it has the same effects in people with stroke is unclear.ObjectivesThe objective of this study was to investigate whether a short, clinically-feasible high-intensity exercise protocol can increase motor cortical excitability in non-exercised muscles of chronic stroke survivors.MethodsThirteen participants with chronic, unilateral stroke participated in two sessions, at least one week apart, in a crossover design. In each session, they underwent either high-intensity lower extremity exercise or quiet rest. Motor cortical excitability of the extensor carpi radialis muscles was measured bilaterally with transcranial magnetic stimulation before and immediately after either exercise or rest. Motor cortical excitability changes (post-exercise or rest measures normalized to pre-test measures) were compared between exercise vs. rest conditions.ResultsAll participants were able to reach the target high-intensity exercise level. Blood lactate levels increased significantly after exercise (p < 0.001, d = 2.85). Resting motor evoked potentials from the lesioned hemisphere increased after exercise compared to the rest condition (p = 0.046, d = 2.76), but this was not the case for the non-lesioned hemisphere (p = 0.406, d = 0.25).ConclusionsHigh-intensity exercise can increase lesioned hemisphere motor cortical excitability in a non-exercised muscle post-stroke. Our short and clinically-feasible exercise protocol shows promise as a potential priming method in stroke rehabilitation.

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