In this study, we investigated corticospinal excitability during mental simulation of a leg extension movement with the technique of transcranial magnetic stimulation. Motor evoked potentials were recorded in both knee extensors (quadriceps) and flexors (biceps femoris) in 19 trained participants (healthy volunteers). The amplitude and latency of motor evoked potentials were compared in three c...

OBJECTIVES To identify the clinical, electrophysiological, and genetic characteristics of a family with an unusual form of hereditary motor neuron disease. METHODS Surviving members of a pedigree in which affected members presented with weakness and atrophy of distal musculature in the upper limbs were examined clinically and electrophysiologically, and had genetic testing. RESULTS The dise...

    Motor units (MUs) reflect the function of the central nervous motor system. Thus, the estimated MU number is a good option to investigate the functional movement disorder in the Parkinson’s disease (PD). The purpose of this study was to compare the estimated MUs number in the medial gastrocnemius (MG) muscle of the normal rats and those with the Parkinsonism. The MG muscle of two age-matche...

The electrical signals produced by the muscles and nerves are analyzed to assess the state of neuromuscular function in subjects with suspected neuromuscular disorders. The repetitive activation of several individual motor units (MUs) results in a superposed pulse train and constitutes the electromyogram (EMG) signal. The analysis of the EMG is based on its basic constituent i.e. motor-unit act...

Intramuscular electromyographic (EMG) signals are detected with needles or wires inserted into muscles. With respect to non-invasive techniques, intramuscular electromyography has high selectivity for individual motor unit action potentials and is thus used to measure motor unit activity. Decomposition of intramuscular signals into individual motor unit action potentials consists in detection a...

The extracellular potential field of isolated frog muscle fibres immersed in a volume conductor was studied at radial distances up to 3 mm during excitation. The shape of the field distant from both the point of the origin of the excitation and the end of the fibre as well as changes in the field when depolarization wave approached the fibre end were described. Different amplitude decrease rate...

A linear relation between surface electromyogram (EMG) amplitude and muscle force is often assumed and used to estimate the contributions of selected muscles to various tasks. In the presence of muscle fatigue, however, changes in the properties of muscle fibre action potentials and motor unit twitch forces can alter the relation between surface EMG amplitude and force. A novel integrative mode...

A sporadic Japanese case of myotonia congenita with painful muscle cramps is reported. Electromyographic examinations disclosed myotonic discharge with dive bomber sounds at insertion, and high-amplitude, high-frequency motor unit potentials during the muscle cramps. Biopsied muscle specimens and EMGfindings showednon-specific mild myopathic changes. There was no abnormal expansion of CTGrepeat...