A Remote Control Brain Telestimulator with Solar Cell Power Supply

A brain telestimulator system is described which can be used with primates weighing 3.0 kg or more. The 3×6×7 cm, 200 gm head-mounted receiver employs solar cells to maintain the charge on its battery, thereby permitting experiments to continue undisturbed for many months. The head unit develops across its output a cathodal, monophasic pulse whose duration, rate, and constant current are remotely controlled from the transmitter. Subject to a duty cycle of 0.1, these parameters are continuously and remotely variable: pulse repetition rate, 0-200 pulses per second; pulse duration, 0.1-3.0 ms; pulse current intensity, 0-1.0 mA with less than ± 3 percent variance for loads between 2500-10 000 ohms. Output pulse rise time is 30 , ¿s. Any one of 12 electrode channels can be selected for stimulation by remote control activation of an electro-mechanical stepping switch in the head unit. Utilization of crystal control in the frequency modulated transmitter and head units permits multi-animal operation by providing separate bands in the 138 MHz region for independent stimulation of up to four animals. The sensitivity of the receiver has purposely been designed low (-35 dBm). Thus, with the present transmitter the system has a range of about 0.2 mile, which extends beyond the normal visual limits of observation of primate groups.