[Evidence and meaning of monophasic potentials in the electromyogram of extraocular muscles of rabbits and cats (author's transl)].

The EMG of extraocular muscles of rabbits and cats was recorded by a concentric-needle electrode provided for clinical use. The EMG showed spike activity (at least biphasic, fast waves of 1 to 2 msec duration) and characteristic long-duration monophasic waves (decline for up to 7 msec). The monophasic potentials are interpreted as local depolarizations arising at the nerve-muscle junctions of multiply innervated muscle fibers. Spike- and monophasic potentials are discharged in independent rhythms whose frequency changes when the head position is altered. The frequency of spike- and monophasic potentials are changed in the same direction by labyrinthine reflexes. Spontaneous monophasic potentials recruit at a lower threshold.