Identification of vestibular sense organs responsible for maculo-ocular reflexes in the frog.

Eye movements evoked by longitudinal and transverse sinusoidal linear accelerations in the horizontal plane were studied in frogs after selective bilateral section of the anterior division (including the utricular, but not the saccular branch), the utricular branch, the posterior division, the lagenar branch or the saccular branch of the VIIIth nerve and compared to responses obtained from intact animals. In frogs with bilateral section of the anterior division of the VIIIth nerve or its utricular branch no eye movements could be evoked in the dark. The maculo-ocular response dynamics in terms of frequency response in animals with selective bilateral saccular or lagenar deafferentation was within the limits of control animals. Our lesion experiments suggest that the utricule and not the lagena or the saccule is mainly responsible for the generation of maculo-ocular eye movements.