Timing of bilateral cerebellar output evoked by unilateral vestibular stimulation in the frog.

Electrical stimulation of one VIIIth nerve evoked simple spike activity in Purkinje cells located on either side of the cerebellum. This cellebullar output was delayed by ca. 10 ms with respect to its mossy fiber-parallel fiber input. The onset of the cerebellar output occurs on the average simultaneously on either side of the corpus cerebelli. The delay is explained by slowly rising EPSPs in PC induced by primary afferent and by second and higher order vestibular fibers. The latter inputs are stronger and terminate ipsi- and contralaterally in the granular layer.