In our own studies we have been impressed by the similarity between the thresholds we have measured for individual responses of heat production and heat loss. Figure 12 summarizes experimentally determined microwave thresholds 5-10-min exposures for the alteration of four types of thermoregulatory responses in terms of both power density mWsq cm and specific absorption rate Wkg. A power density of 6-8 mWsq cm will initiate criterion vasodilation of the tail veins in monkeys restrained in a 26 C environment, an ambient temperature just below the LCT. A slightly lower power density 4-6 mWsq cm wil reliably lower the metabolic heat production of monkeys equilibrated to 15 and 20 C environments, while a power density of 6-8 mWsq cm will initiate thermoregulatory sweating from the foot of monkeys restrained in a 35 C environment, an ambient temperature just below the UCT. Although not discussed in this report, we have also demonstrated that the same power density 6-8 mWsq cm will reliably stimulate squirrel monkeys to select behaviorally an environmental temperature cooler than that normally preferred. The remarkable similarity of these thresholds suggests strongly that the same configuration of deep-body thermosensors is being stimulated by absorbed microwaves to provide the neural impetus for response change.