Clinical Investigation of the Efferent Inhibition of the Vestibular Function

We have investigated the modulation of nystagmus in homo by rotating dizzy patients with constantly increasing acceleration according to a certain computerized scheme or by oscillation with a triangular waveform. We found that the modulation varied greatly in different patients. We saw all variations between hyperreflexive patients, completely lacking inhibition and areflexive patients with a hyperactive inhibition which, however, could be broken by asking the patient to count backwards simultaneously. Habituation of hyperreflexive patients completely lacking their inhibition allowed a normal capacity to habituate. This indicates that there are two different inhibition systems, one fast, appearing during intensive nystagmus and showing a short duration, short time constant (STC), high gain and high reaction readiness, and another type, which is slow and habituating and coming first after iterated stimuli, having a long duration, long time constant (LTC), low initial gain and low reaction readiness. The fi...