Cerebral potentials evoked by muscle stretch in man.
The cerebral potentials evoked by passive plantar flexion movements of the ankle were recorded by scalp electrodes in normal human subjects. The potential consisted of a biphasic positive wave (P45, P65), a prominent negative wave (N90), and a subsequent positive-negative-positive complex (P120, N145, P190). The components of the potential were of largest amplitude at the vertex, small displacements of the active recording electrode resulting in a marked decrease in amplitudes. The amplitudes of the components were also profoundly affected by changes in the repetition rate of the stimulus and by changes in the acceleration of the stretching movements; they were little affected by changes in the extent or peak velocity of stretch provided that acceleration remained constant. Potentials of similar morphology but of slightly shorter latency could be evoked by percussion of the tendon of tibialis anterior and by electrical simuli delivered through a microelectrode inserted into a pure muscle nerve fascicle of the peroneal nerve innervating one of the pretibial flexor muscles. The results of nerve block experiments (ischaemic/pressure block above the ankle; pressure block and local anaesthetic block of the peroneal nerve at the fibular head) suggest that the afferents responsible for evoking the cerebral potential arose from muscle mechanoreceptors. It is concluded that information about muscle stretch arising from muscle mechanoreceptors (probably muscle spindle endings) reaches the cerebral hemispheres of man at short latency and that the resulting potentials can be readily detected using scalp electrodes.
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D000842:Ankle / Q000502:physiology; D001921:Brain / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D009407:Nerve Block; D011930:Reaction Time; D013710:Tendons / Q000502:physiology