Effects of round window stimulation on unit discharges in the visual cortex and superior colliculus.

Abstract

1. The effect of labyrinthine polarization on single cells in the cat visual system was studied in 106 visual cortex and 137 superior colliculus neurons. The principal influence observed in cortex was an increase in unit firing rate above spontaneous activity and a facilitation of the unit's response to light; the dominant effect in colliculus was a decrease in spontaneous firing rate and/or a depression of the unit's response to light. 2. Suppressive effects in colliculus were not mediated by visual cortex, since such suppressive effects were present in cats with visual cortex lesions. 3. Round window stimulation effects were compared to the effects of stimulation calculated to induce general arousal; similar effects were sometimes observed, but different responses were often elicited from the same unit by round window and forepaw or reticular formation stimulation. 4. In cats in which the VIIth–VIIIth nerve complex had been sectioned, round window polarization still had a definite influence on visual neurons. 5. The use of labyrinthine polarization as a method for activating specific vestibular pathways was discussed; experimental evidence suggested that multiple pathways, including non-specific ones, may be activated by round window stimulation.