Comparative effects of pulsed and continuous-wave 2.8-GHz microwaves on temporally defined behavior.

The effects of pulsed-(PW) and continuous-wave (CW) 2.8-GHz microwaves were compared on the performance of rodents maintained by a temporally defined schedule of positive reinforcement. The schedule involved food-pellet reinforcement of behavior according to a differential-reinforcement-of-low-rate (DRL) contingency. The rats were independently exposed to PW and to CW fields at power densities ranging from 1 to 15 mW/cm2. Alterations of normal performance were more pronounced after a 30-minute exposure to the PW field than to the CW field. The rate of emission of appropriately timed responses declined after exposure to PW at 10 and 15 mW/cm2, whereas exposure at the same power levels to the CW field did not consistently affect the rate of responding. Change in performance associated with microwave exposure was not necessarily related to a general decline in responding; in some instances, increases in overall rates of responding were observed.

Modification of the repeated acquisition of response sequences in rats by low-level microwave exposure.

The acute effects of microwave exposure on a repeated acquisition baseline were investigated in three rats. Each session the animals acquired a different four-member response sequence. Each of the first three correct responses advanced the sequence to the next member, and the fourth correct response produced food reinforcement. Incorrect responses produced a three-second timeout. Baseline and control sessions were characterized by a decrease in errors within each session. The animals were acutely exposed to a 2.8 GHz pulsed-microwave field prior to test sessions, with average power densities ranging from 0.25 to to 10 mW/cm2. In comparison to control sessions, 1/2 hour of exposure to microwave radiation at power densities of 5 and 10 mW/cm2 increased errors and altered the pattern of within-session acquisition. Exposure to the 10 mW/cm2 power density decreased the rate of sequence completion in all animals. The results of exposures at 0.25, 0.5, and 1 mW/cm2 power densities were generally within the control range. The results are interpreted as indicating a disruption in the discriminative stimulus control of the repeated acquisition behavior.

Behavioral effects of chlorpromazine and diazepam combined with low-level microwaves.

Previous research findings on the interaction between drugs and microwave radiation were extended to chlorpromazine and to diazepam. The drugs were combined with a 1 mW/cm2 pulsed microwave field (2.8 GHz) and effects were measured on a fixed interval (FI 1) schedule of food reinforcement with rats. Dose-effect functions with and without sham irradiation were established for each drug. At effective doses chlorpromazine consistently decreased rate of responding and reduced with-interval response patterning. Low to moderate doses of diazepam produced little change or increases in response rate, and higher doses produced a decline in response rate. Response patterning within intervals was reduced by increasing doses of diazepam. The animals were exposed to the microwave field alone before test sessions combining the drugs with microwave radiation. Microwave exposure alone did not affect FI performance. Microwave radiation in combination with either drug did not produce any alterations in the dose-effect functions.

Interaction of hyperbaric nitrogen and oxygen effects on behavior.

Breathing elevated environmental pressures of nitrogen and oxygen produced changes in behavior of rats that evidenced an interaction between the two gases. Rates of responding generated by a fixed-interval schedule of reinforcement systematically changed as partial pressures of nitrogen were elevated from 0.8 to 10.4 ATA. Response rates increased above baseline followed by a decline in rates as a function of increasing nitrogen pressure. Concurrent increases in partial pressures of oxygen from 0.2 to 2.2 ATA potentiated the rate-increasing effects of nitrogen at low to moderate nitrogen pressures and enhanced rate-decreasing effects at higher nitrogen pressures. Raised oxygen pressures modulated and interacted with the narcotic effects of nitrogen on behavior.