[Role of optokinetic stimulation in realizing vestibulospinal reflexes]

This paper presents data about the effect of optokinetic stimulation (OKS) on vestibulospinal reflexes and discusses mechanisms of interaction of the vestibular, optic and proprioceptive sensors during their combined stimulation. The vestibulospinal reflexes were investigated using a 2-minute step test and simultaneous OKS that was produced by a portable optokinetic drum mounted on the head of the test subject. During the tests optokinetic nystagmus was recorded and the angle of body rotation relative to the initial position was measured. It was found that during the step test the body turned along the OKS direction, i. e. towards the slow component of optokinetic nystagmus. During leftward OKS the angle of rotation was larger than during rightward OKS: 406.4 +/- 75.9 deg and 207.5 +/- 40.7 deg, respectively. During leftward OKS loss of equilibrium was recorded 4.5 times more often than during rightward OKS. It has been demonstrated that the capacity to track stimuli moving to the left is lower than that to pursue stimuli moving to the right. It has been shown that there is a correlation between the rate of the optokinetic nystagmus slow phase and the angle of body rotation during the step test. It has been concluded that optokinetic nystagmus can be used as an informative parameter when measuring statokinetic stability in response to multisensory stimulation.