ROLE OF THE NEURONAL-ACTIVITY OF NUCLEUS PREPOSITUS-HYPOGLOSSI IN OPTOKINETIC STIMULATION IN THE CAT

The role of the neuronal activity of nucleus prepositus hypoglossi (NP H) in optokinetic stimulation (OKS) and the changes of the activity be tween OKS and off-OKS (resting condition) were investigated in 5 adult cats. In order to make OKS velocity equal to retinal slip velocity, t he cars' eyes were immobilized. The directions of the OKS were clockwi se (CW) and counterclockwise (CCW), and 3 types of velocities, 2 degre es/s, 5 degrees/s and 10 degrees/s, were used. The numbers of spikes o f 37 NPH neurons to OKS did not increase compared with those to off-OK S, also there were no significant differences between those to CW-OKS and CCW-OKS, and between those of the rostral and caudal parts of NPH. The NPH neurons did not react to the retinal slip, and we suppose the result is due to the immobilized eye condition.