Integrator function in the oculomotor system is dependent on sensory context.
The oculomotor integrator is usually defined by the characteristics of decay in gaze after saccades to flashed targets or after spontaneous gaze shifts in the dark. This property is then presumed fixed and accessed by other ocular reflexes, such as the vestibuloocular reflex (VOR) or pursuit, to shape motoneural signals. An alternate view of this integrator proposes that it relies on a distributed network, which should change its properties with sensory-motor context. Here we demonstrate in 10 normal subjects that the function of integration can vary in an individual with the imposed test. The value of the time constant for the decay of gaze holding in the dark can be significantly different from the effective integration time constant estimated from VOR responses. Hence analytical tools for the study of dynamics in ocular reflexes must allow for nonideal and labile integrator function. The mechanisms underlying such labile integration remain to be explored and may be different in various ocular reflexes (e.g., visual versus vestibular).
Chan
W W P
WW
Dept. Biomedical Engineering, McGill University, 3775 University St., Rm 308, Montreal, Quebec H3A 2B4, Canada.
Galiana
H L
HL
D000465:Algorithms; D016001:Confidence Intervals; D004585:Electrooculography / Q000379:methods; D005133:Eye Movements / Q000502:physiology*; D019416:Head Movements / Q000502:physiology; D006801:Humans; D008959:Models, Neurological; D017120:Nystagmus, Optokinetic; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*