O.G. Debowy, J.C. Beck, J.G. McElligott, R. Baker.
No. 266.12. 2002 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2002.
In vertebrates, horizontal eye motions are predominately conjugate; however accumulating evidence indicates that pre-motor neuronal signaling is correlated with movement of one eye. We utilized monocular visual stimuli to elicit visuomotor performance as well as motor learning that included changes in eye position holding. Monocular eye movements were induced by two independent, servo-controlled planetariums (150 visual field, 30 nasal null), each of which also could be controlled by eye position feedback. Sinusoidal monocular visual stimuli (10-20/s at 1/8 Hz vs. 0/s) produced OKR gains of ~ 0.3 vs ~ 0.0, respectively. The horizontal oculomotor integrator time constant also could be altered monocularly to either leak or instability using temporal to nasal visual drift; however, when nasal to temporal drift was employed, time constants were modified in both eyes analogous to our previous observation of VOR gain adaptation. Unidirectional velocity steps produced a monocular direct and indirect component without eye velocity build-up and storage (<2s). OKR stimuli presented out-of-phase (180) to each eye produced oppositely directed eye velocities with gains of ~.2 that elicited conjugate OKR fast phases of differing amplitudes. During all behaviors, the firing rate of hindbrain neurons encoding eye position (Area I) and eye velocity (Area II) were distinctly correlated with ipsilateral eye movement. We conclude that the premotor circuitry in the hindbrain is fundamentally monocular since key hindbrain neurons processing eye position and velocity signals are related to only ipsilateral eye motion.
Supported by: NIH