Horizontal Nystagmus of Rhesus Monkeys

Horizontal optokinetic nystagmus (OKN), caloric nystagmus, and positional alcohol nystagmus (PAN) of the rhesus monkey (Macaca mulatto) were surveyed using electrooculography. OKN of the monkey appears to be similar in most respects to that of man although optokinetic after-nystagmus is more prominent in the monkey. of the parameters of OKN which were measured, slow phase velocity was most closely related to the optokinetic stimulus. Caloric nystagmus is easily induced in the monkey and parameters of caloric nystagmus declined exponentially on repeated testing. The first phase of positional alcohol nystagmus was present in all animals tested and the secondary phase in some. The data indicate that oculomotor findings in the monkey can probably be applied to man with few reservations.