Modeling the role of the interstitial nucleus of Cajal in otolithic control of static eye position.

Previous models of ocular counterroll assumed that static eye position was controlled by direct brainstem pathways from the vestibular nuclei via the ocular motor nuclei to the extraocular eye muscles. However, recent experimental evidence has shown that the interstitial nucleus of Cajal (INC), known as the vertical-torsional velocity-to-position integrator, plays a crucial role in torsional otolith-dependent eye position, i.e. for the modification of Listing's plane by static head tilts. To evaluate possible mechanisms by which otolithic input may influence eye position via the INC, we constructed a 3D mathematical model of saccade and nystagmus generation. The model includes the burst generators located in the rostral interstitial nucleus of the medial longitudinal fasciculus (MLF) and paramedian pontine reticular formation and the velocity-to-position integrators located in the INC and prepositus hypoglossi. The model simulations suggest that otolith pathways to the neural integrator that adjust Listing's plane may involve the cerebellum.