Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation (original) (raw)
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Corticomotor excitability of wrist flexor and extensor muscles during active and passive movement
Human Movement Science, 2010
The excitability of the corticospinal projection to upper and lower limbs is constantly modulated during voluntary and passive movement; however a direct comparison during a comparable movement has not been reported. In the present study we used transcranial magnetic stimulation (TMS) to compare corticomotor excitability to the extensor and flexor carpi radialis (ECR/FCR) muscles of the forearm during voluntary rhythmic wrist movement (through 45°of range), during a matched (for range and rhythm) passive movement of the wrist, and while the wrist was stationary (in mid-range). TMS was delivered when the wrist was in the neutral position. With passive and active movement, and for both FCR and ECR, corticomotor excitability was reduced during lengthening relative to shortening phases of movement. With active movement, this pattern was maintained and superimposed on an overall increase in excitability to both muscles that was greater for the ECR. The results favor a common pattern of excitability changes shared by extensor and flexor muscles as they undergo lengthening and shortening, which may be mediated by afferent input during both passive and active movement. This is combined with an overall increase in excitability associated with active movement that is greater for extensor muscles perhaps due to differences in the strength of the corticomotor projection to these muscles.
Journal of Clinical Neurophysiology, 2008
The purpose of this study was to evaluate the delayed effects of repetitive sensory stimulation with passive wrist movement on corticospinal excitability of the forearm and hand musculature. Motor evoked potential responses to single and double pulse transcranial magnetic stimulation were recorded from the flexor carpi radialis, extensor carpi radialis, and the first dorsal interosseous muscles of the right limb. Data were collected before and after a 1 hour session of passive wrist movement (intervention group, n ϭ 11) or after a same period of rest (control group, n ϭ 9). Motor evoked potential size and area were analyzed to evaluate corticospinal excitability and short interval intracortical inhibition and facilitation. Training with passive movement resulted in a prolonged increase in corticospinal excitability in the flexor carpi radialis and extensor carpi radialis (until at least 1 hour postintervention), but did not evoke significant changes in the levels of short interval intracortical inhibition and facilitation. No such effects were noted in the control group or first dorsal interosseous muscle. Prolonged proprioceptive stimulation with passive wrist movement induces a delayed increase in corticospinal excitability of the forearm muscles. Accordingly, this intervention may promote motor cortical reorganization in the targeted muscles. Results show induced effects from passive movement training that may prove useful for neurorehabilitation therapies.
Neuroscience Letters, 2001
The purpose of this study was to characterize the neuromuscular control during shortening (SHO) and lengthening (LEN) contractions by investigating the input-output (I/O) property in the corticospinal tract. To this end, the relation between various stimulus intensities applied via transcranial magnetic stimulation and the size of motor evoked potentials was investigated in six healthy subjects during elbow flexion and extension. The measured I/O property demonstrates a sigmoidal shape, and is characterized by a plateau value, maximum slope and threshold. The results demonstrated that both the plateau value and maximum slope were significantly lower during LEN contraction than during SHO contraction (P , 0:05), whereas the threshold was found not to be significantly different. These results suggest that both the maximum excitation level and the gain of the corticospinal tract are reduced during LEN contractions.
Brazilian Journal of Motor Behavior, 2020
Background: Although previous studies targeted S1 by TMS to investigate its effect on the corticospinal pathway, there is no evidence if such stimuli produced by TMS would distinctly be restricted to it and not reach M1 interneurons adjacent to S1.Aim: We hypothesized that S1 vs. M1 stimulation-induced MEPs would be similar but smaller and less variable due to the focality of the magnetic pulse, considering that even if TMS is neuronavigated, the magnetic field is not selective enough and reaches M1 interneurons.Method: Healthy volunteers (n = 8, 2 females, age: 29.9 ± 5.49y) received single-pulse TMS over each hemisphere at each intensity of 90, 100, 110, and 120% of rMT in a randomized order. MEPs from the contralateral FCR were recorded.Results: We found no interhemispheric differences, but larger peak-to-peak amplitudes and variability of MEPs after M1 as compared to S1 stimulation. However, latency and waveforms of MEPs did not differ between S1 vs. M1 stimulation supporting th...
Experimental Brain Research, 2010
Unilateral isometric muscle contractions increase motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation not only in the contracting muscle but also in the resting contralateral homologous muscle. Corticospinal excitability in the M1 contralateral to the contracting muscle changes depending on the type of muscle contraction. Here, we investigated the possibility that corticospinal excitability in M1 ipsilateral to the contracting muscle is modulated in a contraction-type-dependent manner. To this end, we evaluated MEPs in the resting left flexor carpi radialis (FCR) during unilateral shortening, lengthening, and isometric muscle contractions of the right wrist flexors at 10, 20, and 30% of maximal isometric contraction force. To compare the effects of different unilateral contractions on MEPs between the contracting and resting sides, MEPs in the right FCR were recorded on two separate days. In a separate experiment, we investigated the contraction specificity of the crossed effect at the spinal level by recording H-reflexes from the resting left FCR during contraction of the right wrist flexors. The results showed that MEPs in the contracting right FCR were the smallest during lengthening contraction. By contrast, MEPs in the resting left FCR were the largest during lengthening contraction, whereas the H-reflex was similar in the resting left FCR during the three types of muscle contraction. These results suggest that different types of unilateral muscle contraction asymmetrically modulate MEP size in the resting contralateral homologous muscle and in the contracting muscle and that this regulation occurs at the supraspinal level.
Effectiveness of muscle vibration in modulating corticospinal excitability
Journal of rehabilitation research and development
This study explored the effect of vibration of the forearm extensors on motor cortical excitability and the influence of stimulus duration. Sixteen healthy volunteers between 23 and 42 years old participated in one or two studies. We applied 15 or 30 min of 100 Hz, 0.5 mm-amplitude vibration to the extensor carpi radialis longus (ECRL) muscle. Cortical excitability was measured as the magnitude of the motor-evoked potentials (MEPs), and the size of the representation area associated with ECRL and flexor carpi ulnaris muscles was determined with the use of transcranial magnetic stimulation. A 33% increase in MEP size and enlarged area of cortical excitability was detected 5 min after 15 min of vibration in the ECRL only. No changes were associated with 30 min of vibration in either muscle. These findings indicate that the facilitatory effects of vibration in healthy subjects depend on stimulus duration and provide impetus for testing the extent to which short-duration vibration augme...
Journal of neuroengineering and rehabilitation, 2014
The combination of voluntary effort and functional electrical stimulation (ES) appears to have a greater potential to induce plasticity in the motor cortex than either electrical stimulation or voluntary training alone. However, it is not clear whether the motor commands from the central nervous system, the afferent input from peripheral organs, or both, are indispensable to induce the facilitative effects on cortical excitability. To clarify whether voluntary motor commands enhance corticospinal tract (CoST) excitability during neuromuscular ES, without producing voluntary muscular contraction (VMC), we examined the effect of a combination of motor imagery (MI) and electrical muscular stimulation on CoST excitability using transcranial magnetic stimulation (TMS). Eight neurologically healthy male subjects participated in this study. Five conditions (resting, MI, ES, ES + MI [ESMI], and VMC) were established. In the ES condition, a 50-Hz stimulus was applied for 3 to 5 s to the firs...
Corticospinal excitability changes following prolonged muscle tendon vibration
NeuroReport, 2003
The present experiment addressed the time course of corticospinal excitability changes following interventional muscle tendon vibration. Using transcranial magnetic stimulation, motor evoked potentials of the £exor carpi radialis and extensor carpi radialis brevis muscle were recorded for a period of 60 min after cessation of vibration (80 Hz, 0.5 mm, 30 min) to the distal wrist £exor tendons. A delayed corticospinal excitability increase in both the vibrated and non-vibrated antagonistic muscle was observed, with lasting levels of facilitation for the latter. No changes were observed following interventional cutaneous vibration. These results underscore a facilitatory in£uence of prolonged Ia-a¡erent activation on corticospinal excitability. Findings are discussed in light of recent advances in promoting motor recovery after brain injury by somatosensory stimulation. NeuroReport14 :1901^1905
Changes in corticomotor excitability following prolonged muscle tendon vibration
Behavioural Brain Research, 2008
The present experiment addressed whether increases in corticospinal excitability following sensory stimulation with muscle tendon vibration are accompanied by reorganization of the forearm musculature representation within the primary motor cortex. Using transcranial magnetic stimulation, we mapped the corticomotor projection to the dominant flexor carpi radialis (FCR) and extensor carpi radialis brevis (ECR) muscle before and after interventional sensory stimulation obtained via muscle tendon vibration (80Hz, 60 min) to the dominant distal wrist flexor tendons. Following vibration, MEP amplitude at the optimal stimulation position, motor output area, as well as map volume, increased significantly for the ECR. None of these effects reached significance for the FCR. These results suggest that the antagonistic vibratory response (AVR), which is considered to be of cortical origin, induces a delayed facilitation of musculature that is antagonistic to the site of the directly activated Ia afferent pathways. This example demonstrates that peripheral sensory stimulation can induce lasting increases in corticospinal excitability in the absence of actual movements.