The mechanism of one of the most striking clinical phenomena, the rhythmic ocular movements appearing on stimulation of the labyrinth, is still a controversial subject. For many years clinicians have tried to localize a "center" of the fast component of nystagmus. It is perhaps appropriate to state the problem in another way, that is to ask on the intactness of which parts of the central nervous system the genesis of rhythmic reaction of the ocular muscles to labyrinthine stimulation depends. The theories put forth in an attempt to answer this question may be divided as follows (Spiegel1 and Spiegel and Sommer2):
The cerebral theory, which attributes the function to the parts of the central nervous system above the midbrain.
Theories assuming that the origin of the rhythm is in parts of the vestibulo-ocular reflex arc.
The various theories of group II may be enumerated as follows:
The proprioceptor theory,