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Paired associative stimulation (PAS) has been shown to increase corticospinal excitability (CSE) providing a promising adjuvant therapeutic approach for stroke. Combining PAS with movement of the stimulated limb may further increase enhancement of CSE, however, individuals with moderate to severe stroke may not be able to engage in the necessary repetitive voluntary movements of the paretic limb. The objective of this study was to investigate the feasibility of contralaterally coordinated PAS (ccPAS) applied to the resting hand extensors during fast extension of the contralateral hand. A potential dependency of CSE modulation on the phase of the movement of the opposite hand was evaluated. Eleven participants each completed three session: PAS applied to the resting right hand during the preparation phase of the extension of the contralateral (left) hand; PAS applied during the execution phase of the left hand extension; and PAS applied with both hands at rest. Motor evoked potentials (MEPs) were evoked from the right extensor digitorum communis (EDC) and flexor digitorum superficialis (FDS) muscles prior and immediately after each session. PAS delivered during the muscle contraction of the left hand and PAS delivered at rest both increased the MEP amplitude in the right EDC. PAS delivered before the left hand movement onset led to a decrease in the MEP amplitude measured in the right EDC muscle. We conclude that PAS induced bidirectional changes in the amplitude of MEPs that were dependent on the phase of the movement of the opposite hand.

Wearable electrodes made of silver nanowires (AgNWs) have demonstrated great potential for sensing a variety of physical and physiological signals. This paper aimed to study the feasibility of AgNWs electrodes for measuring surface electromyographic (sEMG) signals. One human subject was recruited and instructed to perform wrist extension repetitively or to produce no movement in the experiment. sEMG signals were collected from the right extensor digitorum communis of the human subject by an AgNWs electrode and a commercially available Ag/AgCl wet sEMG electrode, separately. The quality of recorded sEMG in time and frequency domains was compared between the two types of electrodes. The results showed that the sEMG signals recorded by the AgNW electrode were comparable with that by the Ag/AgCl electrode. Since the dry AgNWs electrodes are flexible, wearable, and potentially robust for daily use, novel AgNW-based EMG electrodes are promising for many biomedical applications, such as myoelectric control of artificial limbs.

Motor unit action potential (MUAP) measurement parameters are reported to be affected by the type of needle electrode. MUAP amplitude measured with monopolar electrodes has been reported to be up to twice the amplitude recorded with concentric electrodes. We hypothesized that with current technology the difference in recordings from the two needles should be minimal and of little clinical significance. The right extensor digitorum communis muscle was examined in 15 healthy volunteers with first a concentric and then a monopolar needle. The filter band-pass of the electromyograph was 20 Hz to 10 kHz. Four first-recruited MUAPs were isolated by using each electrode. A separate muscle insertion was performed to locate each potential. Amplitudes were maximized. Consecutive MUAPs were averaged and measured. The mean (+/- SD) values of the measurements were as follows: amplitude: monopolar, 1038 (+/- 369) microV; concentric, 912 (+/- 315) microV; duration: monopolar, 10.8 (+/- 2.0) ms; concentric, 9.7 (+/- 1.7) ms. No statistically or clinically significant differences exist between these measurement values.