//Behavioral alteration was characterized by decrements in response rate but not by changes in reaction time, yellow light errors, and postreinforcement pause time. There are two distinct explanations for the singular effect of microwave pulses on response rate. First, the reduction of response rate may be due to an auditory sensation during microwave exposure and subsequent distraction of the animal from producing the normally consistent rates of responding during the red light. People have reported a hearing effect produced by pulsed microwaves. An early report described the effect as "clicks" or "hissing" located behind the head (10), that required pulsed energy for its occurrence. Several important studies have verified the hearing sensation (11) and measured cochlea microphonics produced by pulsed microwaves (12). Foster and Finch (13) suggested that the hearing effect was due to a thermoelastic expansion of tissue during absorption of a microwave pulse with a subsequent thermoacoustic pressure wave propagating through tissue producing the hearing effect by stimulating receptor cells located within the cochlea of the ear. It is reasonable to assume that the energy delivered to the head of our monkeys was well above the threshold for the hearing effect (14).//
//From this study, we can say that the threshold for exposure of the head to pulsed microwaves lies between 16 and 26 W/kg. The threshold for changes in behavioral performance during whole-body exposure to microwaves has been reported to be near 4 W/kg. The safety standards (1,2) employ a safety factor of 10 placing the maximum permissible SAR at 0.4 W/kg. The safety standards also employ a localized maximum SAR [specific absorption ratio] in any 1 g of tissue at 8 W/kg. The threshold range determined in this study for a localized exposure to the head to produce a behavioral effect of 16 to 26 W/kg suggests that the 8 W/kg safety standard does not provide a safety factor of 10.//
My favorite interlude:
//DOSIMETRY: The rhesus monkey carcass was mounted in the Plexiglas chair and positioned in the anechoic chamber to simulate behavioral test sessions. Four temperature probes were inserted into the carcass at various depths followed by microwave exposure at 9 pps for 180 s. Small holes were drilled in the back and top of the skull and small plastic cannulae inserted into the brain. Two locations along the vertical central axis and one along the horizontal central axis of the cranial cavity in the head were sampled at 10, 16, and 26 mm as measured from the surface of the brain. The fourth sample site was the center of the neck. Tissue temperatures were recorded every 10 s before, during, and after exposure to microwaves. Identical measurements were made after two different microwave exposures. The local SAR was calculated using the following formula: SAR (W/kg) = 4.186cT/t where T is the temperature change in degrees Celsius, c is the specific heat for brain tissue in cal/g/°C, and t is the exposure time in seconds. Average SAR of the whole head was estimated with the saline-filled balloon by measuring the temperature of the saline and quickly placing it on the Plexiglas restraint chair in the location of the monkey's head and irradiating it for 180 s. The balloon was then quickly agitated to provide mixing, the temperature was remeasured, and the SAR was calculated using the formula given above.//
//BEHAVIORAL: The monkeys were placed on restricted food rations and then trained by successive approximation to operate two levers for food pellet reward. This task, diagramed in Fig. 2, required the monkey to respond on one lever in the presence of a red light. The first response on this lever at the end of a variable time interval (30 s average, 2-140 s range) turned off the red fight and turned on either a green light (75% of the trials) or turned on a yellow light (25% of the trials). The green and yellow lights were illuminated for 1 s. A response on a second Iler while the green light was illuminated resulted in a food pellet reward. A response on the second lever in the presence of an illuminated yellow light was followed by a 30-s time out with the anechoic chamber lights and the stimulus panel lights (red, green, yellow) turned off. The sequence of red light responding followed by either a yellow or green light was typically repeated 100-120 times in a single behavioral test session. The behavioral session lasted 77 min and consisted of three 25-min components separated by 1-min extinction periods. During the extinction periods, the levers were ineffective, and all lights were turned off. Microwave exposures were always given during the middle 25-min component allowing three distinct behavioral evaluations: premicrowave, microwave, and postmicrowave.//
Suggested thought experiment: If you believe AIs are at least as sentient as rhesus monkeys consider the discipline and ethics implications of this typical monkey study when handling the AI for testing and applications.
