1 Research and instrumental development fro the construction of the stimoceiver was supported by the United States Air Force, 6571st Aeromedical Research Laboratory F 29600-67-C- 0058. Additional support for our research was provided by the United States Public Health Service, M-2004, and the Office of Naval Research, 609 (48). The circuit for EEG recording is a modified version of the unit described by Meehan (1965), and his help in providing us with the information and one of his units is gratefully acknowledged. The help of Mr. Per Ha...[unreadable] developing telestimulation is also gratefully acknowledged. During the last few years, methodology has been developed to stimulate and record the electrical activity of the brain in completely unrestrained monkeys and chimpanzees (Delgado, 1967; Delgado and Mir, in press). This procedure should be of considerable clinical interest because it permits exploration of the brain for unlimited periods without disturbing their rest or normal spontaneous activities. [EW: Dr. Delgado, you are all heart!] This paper reports instrumentation used and clinical application in four patients with psychomotor epilepsy in whom electrodes had been implanted in the temporal lobes. To our knowledge, this is the first use of intercereb- ral radio stimulation and recording in man. METHODS page 185 Implantation of electrodes Electrodes were constructed and stereotaxically implanted according to methods previously described (Mark & Ervin, 1969). The electrode assemblies which were connected to a McPherson skull plug, consisted of a plastic stylet, 1.2 mm in diameter, with 15 stainless steel ? mm wide contacts at 3 mm intervals, plus one thermistor and three other contacts at the tip. Using a McPherson Type 2 stereotaxic machine (Mark & Ervin, 1969), electrode assemblies were implanted ???laterally into the anterior medical amygdala of each patient. Radio Stimulation This system consists of two instruments: (1) the RF transmitter that measures 30 cm x 25 cm x 15 cm and includes the circuitry for controlling repetition rate, duration, and amplitude (intensity) of the stimulating pulse. The repetition rate may be varied in steps between 10 and ?? Hz and the duration between 0.1 and 1.5 millisec. Single pulses may also be generated. -131-