Contribution of oculomotor signals to the behavior of rabbit floccular Purkinje cells during reflex eye movements.
Alert pigmented rabbits were stimulated in 3 ways: (1) weak repetitive electrical stimulation (10-30 Hz) of an optic tract which induced nystagmic and after-nystagmic eye movements; (2) sinusoidal whole-body oscillation (5 degrees peak-to-peak, 0.1 Hz) which induced the horizontal vestibulo-ocular reflex (HVOR); (3) sinusoidal oscillation (2.5 degrees, 0.33 Hz) of a screen with a dot pattern which drove the horizontal optokinetic eye movement response (HOKR). Single units were recorded from Purkinje cells in the floccular H-zone where local stimulation caused a horizontal shift of the eyes. During slow phases of optic-tract-induced nystagmus and after-nystagmus, most of the H-zone Purkinje cells tested exhibited changes in discharges of simple spikes, an increase at a mean rate of 1.74 for ipsilaterally directed and 1.17 [spikes/s]/[deg/s] for contralaterally directed eye velocity. One-third of the H-zone Purkinje cells changed simple spike discharges depending on the eye position. During HVOR, most of the H-zone Purkinje cells exhibited a modulation of simple spike discharges 180 degrees out of phase to head velocity, the mean amplitude of modulation being 9.3% of the mean discharge rate. During HOKR, these cells also exhibited modulation by 13.8% in phase to screen velocity. No specific localization was found as to the relative intensities of these responses. It is estimated that an eye velocity component accounts for 18-20% and an eye position component for 5-14% of the responses of floccular H-zone Purkinje cells during HVOR and HOKR.
Nagao
S
S
Department of Physiology, Faculty of Medicine, University of Tokyo, Japan.
D000818:Animals; D002531:Cerebellum / Q000033:anatomy & histology / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials; D007839:Functional Laterality; D009760:Nystagmus, Physiologic; D009802:Oculomotor Nerve / Q000502:physiology; D011689:Purkinje Cells / Q000502:physiology*; D011817:Rabbits; D012027:Reflex, Vestibulo-Ocular; D014795:Visual Pathways / Q000502:physiology*