Photic cuing of escape by rats from an intense microwave field

A total of 16 female hooded rats was first observed for baseline behaviors and then they received 25 2-min trials of training, five trials per day, under one of four stimulus conditions (all ns = 4): exposure to a highly intense 918-MHz field (dose rate, 60 mW/g); exposure to photic stimulation (approximately 350 1x); exposure to the field in synchrony with photic stimulation; or exposure to faradic shock (approximately 800 micro A rms). During conditioning trials, which were separated by 2-min intertrial intervals, entry by a rat into a safe area of a multimode cavity resulted in immediate and complete cessation of stimulation; exit, in resumption. Acquisition of the escape response was rapid and highly efficient for shocked animals and was less rapid and efficient but was reliably demonstrated by irradiated animals that were also signaled by light. In the absence of microwave irradiation, cessation of light did not reliably motivate escape behavior. Although there was weak evidence of escape learning by rats subjected only to microwave irradiation, their performance failed to differ reliably from those of rats in the light-only condition. These data confirm and extend those of Carroll et al, which indicate that potentially lethal, deeply penetrating, nonpulsed microwaves in a multipath field lack the sensory quality to motivate efficient aversive behavior by the rat.