Eye hyperdeviation in mouse cerebellar mutants is comparable to the gravity-dependent component of human downbeat nystagmus.

摘要: Humans with cerebellar degeneration commonly exhibit downbeat nystagmus (DBN). DBN has gravity-independent and -dependent components, the latter been proposed to reflect hyperactive tilt maculo-ocular reflexes (tilt-MOR). Mice genetically determined ataxia do not DBN, but they tonic hyperdeviation of eyes, which we have be equivalent. As such, tilt-MOR might predicted in these mutant mice. We measured 10 normal C57BL/6 mice 6 tottering, a exhibiting ocular motor abnormalities due mutation P/Q calcium channel. Awake were placed body orientations spanning 360 degrees about pitch axis. The absolute, equilibrium vertical angular deviations one eye using infrared videooculography. In both strains, elevation varied quasi-sinusoidally angle range 90 nose-up nose-down. Beyond this returned neutral position. Deviation over +/-30 was an approximately linear function projection gravity vector into animal's horizontal plane, can thus summarized by its slope (sensitivity). Sensitivity 14.9 degrees/g for 20.3 statistically significant difference. Thus otolithic reflex ataxic mutants is relative controls could explain consistent idea that analogous DBN.