Evidence for independent feedback control of horizontal and vertical saccades from Niemann-Pick type C disease (original) (raw)
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Frontal eye field signals that may trigger the brainstem saccade generator
Progress in brain research, 2008
Saccades are rapid shifts of gaze that normally place the line of sight on a desired target with a single smooth movement. A number of disease states have been shown to result in saccadic movements that are fragmented, but still end near target position after a multi-step sequence of saccades. Among these disorders are Parkinson's disease and late-onset Tay-Sachs disease (LOTS). We have recently shown that normal human subjects and monkeys also make some two-step saccadic responses in cognitively difficult, choice response tasks. In monkeys we have been able to record neuronal responses as the animals performed a visually guided, choice saccade task. We compared the activity of neurons in the superior colliculus (SC) and the cortical frontal eye field (FEF) during the majority of trials that were accomplished with single-step saccades with those completed with two-step saccades. Several differences in discharge pattern aligned on the first saccade were uncovered. Neurons in the ...
Journal of Neurophysiology, 2021
The caudal fastigial nuclei (cFN) are the output nuclei by which the medio-posterior cerebellum influences the production of saccades toward a visual target. On the basis of the organization of their efferences to the premotor burst neurons and the bilateral control of saccades, the hypothesis was proposed that the same unbalanced activity accounts for the dysmetria of all saccades during cFN unilateral inactivation, regardless of whether the saccade is horizontal, oblique, or vertical. We further tested this hypothesis by studying, in two head-restrained macaques, the effects of unilaterally inactivating the caudal fastigial nucleus on saccades toward a target moving vertically with a constant, increasing or decreasing speed. After local muscimol injection, vertical saccades were deviated horizontally toward the injected side with a magnitude that increased with saccade size. The ipsipulsion indeed depended upon the tested target speed, but not its instantaneous value because it di...