Behavioral effects of microwave reinforcement schedules and variations in microwave intensity on albino rats

Behavioral and cognitive effects of microwave exposure

This paper presents an overview of the recent behavioral literature concerning microwave exposure and discusses behavioral effects that have supported past exposure standards. Other effects, which are based on lower levels of exposure, are discussed as well, relative to setting exposure standards. The paper begins with a brief discussion of the ways in which behavioral end points are investigated in the laboratory, together with some of the methodological considerations pertinent to such studies when radio frequency (RF) exposure is involved. It has been pointed out by several sources that exposure to RF radiation can lead to changes in the behavior of humans and laboratory animals that can range from the perceptions of warmth and sound to lethal body temperatures. Behavior of laboratory animals can be perturbed and, under certain other conditions, animals will escape and subsequently avoid RF fields; but they will also work to obtain a burst of RF energy when they are cold. Reports of change of cognitive function (memory and learning) in humans and laboratory animals are in the scientific literature. Mostly, these are thermally mediated effects, but other low level effects are not so easily explained by thermal mechanisms. The phenomenon of behavioral disruption by microwave exposure, an operationally defined rate decrease (or rate increase), has served as the basis for human exposure guidelines since the early 1980s and still appears to be a very sensitive RF bioeffect. Nearly all evidence relates this phenomenon to the generation of heat in the tissues and reinforces the conclusion that behavioral changes observed in RF exposed animals are thermally mediated. Such behavioral alteration has been demonstrated in a variety of animal species and under several different conditions of RF exposure. Thermally based effects can clearly be hazardous to the organism and continue to be the best predictor of hazard for homosapiens. Nevertheless, similar research with man has not been conducted. Although some studies on human perception of RF exist, these should be expanded to include a variety of RF parameters.

Acetaminophen effects on behavioral thermoregulation in albino rats

Acetaminophen (N-Acetyl-p-aminophenol) was administered intraperitoneally to 15 Sprague-Dawley rats partitioned into 3 studies (5 rats per study) using a within subjects, repeated-measures reversal design. Behavioral thermoregulation was assessed in a cold Skinner Box using 5-sec. exposures of microwave radiation [Specific Absorption Rate = 0.34 Watts/kg/(mW/cm2)] as reinforcing stimuli under a fixed-interval 2-min. schedule of positive reinforcement. Doses of 10, 20, 30, 40, and 50 mg/kg (in solutions of 1%, 2%, 3%, 4%, and 5%) acetaminophen showed stable rates of operant responding for heat compared with significant changes in rates for comparable doses of aspirin in a 1993 study by Vitulli, et al. Weight reductions and temperature increases varied significantly with before-session and after-session measures, respectively. 1994-95 biochemical data of Murphy, et al. from humans following aspirin or acetaminophen ingestion which affect thermoregulation and sleep patterns are discussed in conjunction with behavioral data from rats.

Aspirin (acetylsalicylic acid) effects on behavioral thermoregulation with microwave radiation

Aspirin is a widely used over-the-counter drug in our society which has wide therapeutic value, yet not all of the behavioral side effects have been studied. Different doses of aspirin solutions were administered (ip) prior to fixed-interval 2-min. schedules of microwave reinforcement in rats tested in a cold environment. Four Sprague-Dawley rats were conditioned to regulate their thermal environment with 5-sec. exposures of MW reinforcement. Friedman's nonparametric test showed significant differences among aspirin and saline-control doses. Post hoc sign tests showed that a moderate dose of aspirin increased operant behavior reinforced by MW radiation, yet lower and higher doses decreased and then increased the rate of responding which resulted in an inverted U-shaped trend. Possible multiple effects of aspirin in terms of its thermoregulatory as well as its pain-tolerance properties, and implications for hypothalamic "set point" are discussed.

Alcohol effects on behavioral thermoregulation with microwave radiation

Ethanol may play an active role in modifying "set point" levels in conjunction with behavioral thermoregulation. A geometric series of doses of ethanol solutions was administered (ip) prior to fixed-interval 2-min. schedules of microwave reinforcement in rats tested in a cold environment. Four Sprague-Dawley rats were conditioned to regulate their thermal environment with 5-sec. exposures of MW reinforcement. Friedman's nonparametric test showed significant differences between ethanol doses, and Sign tests showed that moderate and high doses of ethanol suppressed operant behavior reinforced by MW radiation. Interactions between changes in "set-point" and discriminative properties of ethanol are discussed.

Caffeine effects on behavioral thermoregulation

Caffeine has a wide range of behaviorally active properties. Varying doses of caffeine solutions were administered (ip) prior to fixed-interval 2-min. schedules of microwave reinforcement in rats tested in a cold environment. Four Sprague-Dawley rats were conditioned to regulate their thermal environment with 5-sec. exposures of microwave reinforcement. Graphic descriptions showed that small doses of caffeine produced higher response rates for microwave heat than high doses of caffeine and saline controls, yet Friedman's nonparametric test showed no significant differences between dose levels. Synergism between thermogenic and discriminative properties of caffeine is proposed.

Insulin and dextrose effects on fixed-interval behavioral thermoregulation in albino rats

This study is a systematic replication of the effects of insulin doses on operant behavior reinforced (in an earlier study) by fixed-ratio schedules of microwave (MW) reinforcement. In this study, insulin and dextrose doses were administered (ip) prior to fixed-interval 2-min. schedules of MW reinforcement in rats tested in a cold environment. Six Sprague-Dawley rats were conditioned to regulate their thermal environment with 5-sec. exposures of MW radiation (SAR = 0.34 Watts/kg/(mW/cm2) under the FI-2' schedules. Humulin-regular insulin and 50% solutions of dextrose were administered (ip) alternately with saline control sessions for 8-hr. durations. A within-subjects, repeated-measures 4 x 8 x 3 factorial analysis of variance design showed that insulin doses suppressed operant responding for heat, which confirmed the results of the earlier study under a different schedule. In addition, high doses of dextrose had similar suppressing effects on operant responding for heat. The data are interpreted in terms of the discriminative properties of increased thermogenesis produced by the insulin and dextrose doses. The suppressing effects were more pronounced for the first two hours, yet they persisted for approximately six hours of the 8-hr. sessions.

Insulin, exercise, and dietary effects upon behavioral thermoregulation in albino rats

The objectives of this exploratory research were to assess the effects of insulin preparations (Humulin-regular and NPH) on operant behavior reinforced by schedules of microwave radiation in a cold environment and to measure changes in this thermoregulatory behavior as a function of exercise and food deprivation. Eight albino rats were conditioned to regulate their thermal environment with 6-sec. exposures of microwave (MW) radiation (SAR = 0.34 Watts/kg/(mW/cm2) under FR-1 and FR-10 schedules. Regular-insulin and NPH-insulin sessions were administered alternately with saline-control sessions for 8-hr. durations. Exercise in an activity wheel and 48 hr. of food deprivation (diet) were additional independent variables used to alter thermoregulation. Three randomized-block analysis of variance designs with repeated measures showed that insulin preparations resulted in a suppression of operant responding for heat, yet food deprivation increased rates of microwave responding. These data are interpreted in terms of functional relationships between ambient temperature changes, core body temperature, blood glucose fluctuations, and operant behavior.