Flash induced nystagmus (FIN) in the rabbit: input-output relations.

Flash-induced nystagmus (FIN) was elicited by monocular flicker-stimulation at 20-40 Hz. It was found more often in albino than in pigmented rabbits. Slow phase velocity (SPV) showed a gradual increase, then a steady-state level in most animals and an after-response after cessation of stimulation. incremental and decremental phase mainly showed an exponential change in SPV. Apparent time constants were in the range of 5-40 sec. Simultaneous recording of both eyes revealed greater velocity and amplitude of both phases of FIN in the stimulated eye. FIN can be specified as a type of nystagmus that is evoked by monocular essentially open-loop stimulation of the crossed ("subcortical") visual pathway. Direction-selective elements in the retina may play a specific role and their predominant orientation gives rise to nystagmus in adducting direction in the flicker-stimulated eye as if it were exposed to optokinetic stimulation in the temporonasal direction.