[Somatosensory-visual-vestibular interaction in a case of vermis agenesis].

It is well known that the somatosensory input is important for keep a balance as well as the visual and the vestibular inputs. However the knowledge of somatosensory-visual-vestibular interaction is incomplete at now. We have already made a mathematical model of these interactions by extension of the Raphan-Cohen model (Raphan et al, 1979) for visual-vestibular interaction with a direct and an indirect somatosensory pathway. This indirect somatosensory pathway has access to the common visual-vestibular velocity storage integrative mechanism. So the purpose of the present experiment was to verify whether such an extended model (Fig. 4) can be used to describe the nystagmus due to stimulation of the sensory system apart or in combination in case of vermis agenesis with Dandy-Walker's cyst. It was checked, on the other hand, where the lesion are extended. And moreover it was suspected that each parts of the mathematical model are compared with any central neural regions. As a result, the indirect pathways of visual, vestibular and somatosensory inputs and the direct pathways of visual and somatosensory inputs were disturbed completely. The disturbance of the indirect pathways was caused by lesion in the velocity storage integrator which was though to be included in the vestibular nuclei in monkey. The lesion in epsilon 3-h2 was suspected to explain a blockage of the direct visual pathway, and a disturbance of the direct somatosensory pathway was suspected the lesion in gs. We could explain this cause by a mathematical model for somatosensory-visual-vestibular interaction, so we could conclude that this model was useful for human beings as well as monkey.(ABSTRACT TRUNCATED AT 250 WORDS)