A head enclosure for exposing monkeys to selected gas mixtures.

An acrylic head enclosure, permitting rapid exchanges of atmospheric gases, was developed for investigations of physiologic and performance responses of small nonhuman primates to graded hypoxic hypoxia and hypercapnia. The total system included a neck yoke plate which served both as a physical barrier to arm and hand movements in the head area and as a base on which to rest the head enclosure. The transparent, airtight, head enclosure permitted rapid exchanges of controlled gas mixtures and the execution of performance tasks in an apparently comfortable experimental environment.