A nystagmus strategy to linearize the vestibulo-ocular reflex

Two important aspects of the vestibulo-ocular reflex (VOR) are addressed. First, the linear range of ocular responses is much more extensive than expected from the characteristics of central pathways (CNS), and this is shown to result directly from early convergence of fast and slow premotor signals in the central processes, associated with significant and intermittent changes in functional connectivity (effective structural modulation). Second, the presence of such structural modulation implies that responses must be analyzed using transient analysis techniques, rather than previous steady state approaches, in order to properly evaluate reflex dynamics. Simulation results with a recent model of the VOR are used to illustrate the arguments. Relying on known interconnections between saccadic burst circuits in the brainstem, and the ocular premotor areas of the vestibular nuclei, a viable strategy for the timing of nystagmus events is proposed. The strategy easily reproduces the characteristic changes in vestibular nystagmus with the amplitude of head velocities, and with the frequency of passive head oscillation.