Chemistor: a reusable telestimulation device for direct chemical stimulation of the nonhuman primate brain in freely moving animals.

A reusable telemetric multi-injector unit (chemistor) suitable for injections into the brain of primates has been developed and tested in chronic experiments with rhesus monkeys freely moving and interacting with other monkeys. The chemistor unit, which measures 15.0 by 15.0 by 7.5 mm and weight 5.8 g, consists of a microinjector, equipped with an internal mechanical power source, and an electronic circuit connected with a receiving coil; a total volume of 27.0 mul to be injected in quanta of 0.9 mul at freely chosen time intervals makes this unit suitable for 30 injections. The desirable protection against possible damage is provided by a circular, head-mounted container (dia. 43.0 mm and 10.3 mm high) which leaves place for two complete chemistors. The device is small, light in weight, reliable and resistant to physical damage.