[Torsional movements of the human eye. II. Slow phase of torsion].

At different experimental conditions quantitative characteristics of the slow phase of the torsional eye movements were investigated. We found the torsional drift to increase when the head tilted faster and its velocity was bigger in the dark than in the light. Asymmetry of the drift velocity was found on moving the head to and backward. It was shown that the sign of the asymmetry did not depend on rotatory movements of the cup (the suction device for eye movement registration). At the same time electric stimulation of the labyrinth changed the sign of asymmetry and without head tilting led to the torsional eye movements (nistagmus). Some subjects were able to decline the number of the torsional saccades at will, and as a result the eye made a drift up to tens of degrees long. Possible causes of imperfect vestibular and optokinetic compensation in the eye trosion were discussed.