Sensitivity of lateral cerebellar nucleus to macular stimulation in the rabbit

Experiments were performed in decerebrate rabbits to determine the sensitivity of the lateral cerebellar nucleus (LCN) to macular stimulation. Twenty-three percent of the neurons recorded extracellularly in the LCN showed steady changes in their discharge rate during 20 degrees tilt in both directions of the medial plane. Most of these neurons exhibited an alpha- and beta-type of response. A few gamma-types, but no delta-types were observed. The units sensitive to tilt were restricted to the caudal half of the LCN. Some of these positionally sensitive neurons responded monosynaptically to ipsilateral labyrinthine stimulation, but many received a polysynaptic input. These units could be activated antidromically by stimulation of the oculomotor nucleus but at a very high intensity suggesting current spread to the nearby brachium conjunctivum fibers. These results exclude a role of the LCN in the disynaptic otolith-ocular reflex.