Vestibulo-oculomotor Relations: Static Responses

It is generally agreed that the otolith organs, the utricle, and saccule perceive linear acceleration and gravity. Because of their role in sensing the position of the head in relation to gravity, Breuer designated the otolith organs as the organs of the Statischer Sinn (static sense). The semicircular canals are generally considered to respond only to angular movement of the head, not to gravity, although this is disputed by several authors. In this chapter, eye movements induced by stimulation of the utricular nerve is described, and effects of the semicircular canals on a “static” vestibulo-ocular reflex, positional alcohol nystagmus, is demonstrated. The data indicate that the function of the semicircular canals and otolith organs may not be as separate as has been previously assumed. Eye deviations are produced in cats and rabbits in side down positions before and after alcohol intoxication. After alcohol, horizontal deviations become dominant and rotatory movements are less prominent. In intoxicated cats, it is shown that intact lateral canals are necessary to produce the horizontal components of positional alcohol nystagmus in side down positions. There is some indication that the labyrinth on the opposite side induced the rotatory components of this nystagmus.