Rats were repeatedly presented an opportunity to escape from an intense 918 MHz field (60 mW/g) to a field of lower intensity (40, 30, 20, or 2 mW/g) by performing a simple locomotor response. Other rats could escape 800 µA faradic shock to the feet and tail by performing the same response in the same milieu.
|Chamber||cavity 44.0 x 58.0 x 39.0 cm|
|Additional info||22 parallel, equidistant 5 mm stripes of conductive silver paint used for 800 µA faradic shock|
None of 20 exposed rats learned to associate entry into a visually well-demarcated area of the cavity with immediate reduction of dose rate, in spite of field-induced increases of body temperature to levels that exceeded 41°C. In contrast, all of ten animals motivated by faradic shock learned to escape. The failure of escape learning by exposed rats probably arose from deficiencies of motivation and, especially, sensory feedback. Whole-body hyperthermia may lack the painful or directional sensory properties that optimally promote the motive to escape. Moreover, a decrease of body temperature after an escape-response-contingent reduction of field strength will be relatively slow because of the large thermal time constants of mammalian tissues, so that the animals seem to fail assigning cause and effect.