Vestibulo-ocular responses in man during sleep

Abstract

The vestibulo-ocular response of human subjects to prolonged oscillatory rotational stimulation has been investigated during various stages of sleep and arousal. Five stages of oculomotor response are described as follows: Stage I: Awake and alert but with eyes shut yields normal compensatory nystagmus. Stage II: Drowsy or light sleep radically changes the response to one which is devoid of sharp saccades and is 90–180° phase shifted relative to that required for compensation. Stage III: A deeper level of sleep abolishes any correlated response, leaving only large, uncorrelated wandering eye movements. Stage IV: Subsequently the original correlated response, but without saccades, returns, superimposed on wandering eye movements. Stage V: In deep sleep all responses virtually disappear. It is proposed that these effects could be accounted for first by desynchronization of saccadic hurst activity in oculomotor neurons and then by preferential suppression of the resulting degraded, or smoothed “saccadic” signal relative to the primary compensatory one. Eventually in deep sleep suppression of both signals would lead to Stage V. It is shown that appropriate modification of a previously described model of the vestibulo-ocular system of the cat can simulate the major findings on this basis. Rapid eye movement phase of sleep was not observed during the continuous oscillatory stimulus.