Effects of pontine reticular formation lesions on optokinetic head nystagmus in rats.

Electrolytic lesions were produced in the pontine reticular formation (PRF) of adult hooded rats. Unilateral lesions abolished quick phases of optokinetic head nystagmus to the side of the lesion. Some lesions also had temporary effects on slow phases of optokinetic head nystagmus. Effects of bilateral lesions were similar, except that they affected head movements in both directions. A class of "fast" head movements abolished by PRF lesions thus emerges that is analogous to the class of rapid eye movements abolished by similar lesions in other species, a finding that can be related to the coupling which has been observed between "fast" head and eye movements.