Squirrel monkeys and space motion sickness.

Studies of the vestibular system in squirrel monkeys in consideration of space motion sickness (SMS) or space adaptation syndrome (SAS) were reviewed. First, the phylogenetic position of the squirrel monkey was considered. Then the anatomico-physiological studies of both the peripheral and the central vestibular systems were described, because the vestibular system is crucially important in the genesis of SMS (SAS). In this connection, the ablation studies of labyrinth, semicircular canals, and other SAS-related areas were referred to, and consideration was made for experiments about caloric irrigation of the ear. A hypothetic model was then proposed for the genesis of SAS.