Motor-evoked potentials (MEPs) after transcranial magnetic stimulation (TMS) show a trial-to-trial variation in size at rest that is positively correlated for muscles of the same, and opposite, upper limbs. To investigate the mechanisms responsible for this we have examined the effect of voluntary activation on the correlated fluctuations of MEP size. In 8 subjects TMS was concurrently applied ...

It is conventionally considered that because of their fiber orientations, the external intercostal muscles elevate the ribs, whereas the internal interosseous intercostals lower the ribs. The mechanical action of the intercostal muscles, however, has never been studied directly, and the electromyographic observations supporting this conventional thinking must be interpreted with caution. In the...

Long train (50) electrical pulses were applied to the ulnar, median, and deep peroneal nerves. The probability of firing, or firing index, of the first motor units (MU) recorded by surface and needle electrodes in the first dorsal interosseous, thenar, and extensor digitorum brevis muscles varied from 0-100% as the stimulus was increased from a minimum threshold voltage (V) to V + delta V (delt...

Blind intramuscular injection might cause severe neurovascular injury if it would be performed with insufficient knowledge of anatomy around the injection area. We report a case of pseudo-anterior interosseous syndrome caused by multiple intramuscular steroid injections around the antecubital area. The patient had weakness of the 1st to 3rd digits flexion with typical OK sign. Muscle atrophy wa...

During effortful unilateral contractions, muscle activation is not limited to the target muscles but activity is also observed in contralateral muscles. The amount of this associated activity is depressed in a fatigued muscle, even after correction for fatigue-related changes in maximal force. In the present experiments, we aimed to compare fatigue-related changes in associated activity vs. par...

The neuromuscular strategies employed to compensate for fatigue-induced muscle force deficits are not clearly understood. This study utilizes surface electromyography (sEMG) together with recordings of a population of individual motor unit action potentials (MUAPs) to investigate potential compensatory alterations in motor unit (MU) behavior immediately following a sustained fatiguing contracti...