Thermal tolerance reduces hyperthermia-induced disruption of working memory: a role for endogenous opiates?
Mickley GA, Cobb BL · 1998
View Original AbstractMicrowave radiation at 9.3 W/kg disrupted rats' working memory through heating effects, though prior exposure created protective tolerance.
Plain English Summary
Researchers exposed rats to microwave radiation at levels that caused significant body heating and found it disrupted their ability to distinguish between familiar and new objects - a key indicator of working memory function. However, rats that had been previously exposed to the heating developed a tolerance that protected them from both the temperature increase and memory problems. The study suggests that microwave-induced heating can impair cognitive function, but the brain may adapt to protect itself from repeated exposures.
Why This Matters
This research provides important insights into how radiofrequency radiation affects cognitive function through heating mechanisms. The 9.3 W/kg exposure level used here is nearly five times higher than the current SAR limit for cell phones (2 W/kg), representing extreme heating conditions. What makes this study particularly significant is its demonstration that even brief microwave exposures can disrupt working memory - the cognitive system we rely on for processing new information and making decisions. The finding that prior exposure creates tolerance raises complex questions about whether adaptation protects us or potentially masks ongoing harm. While the extreme exposure levels make direct comparisons to everyday device use challenging, the study reinforces that heating effects from EMF exposure can have measurable impacts on brain function. The research adds to a growing body of evidence suggesting that our cognitive abilities may be more vulnerable to electromagnetic fields than previously understood.
Exposure Details
- SAR
- 9.3 W/kg
- Source/Device
- 600-MHz
- Exposure Duration
- 5 successive days, 20-min
Exposure Context
This study used 9.3 W/kg for SAR (device absorption):
- 23.3x above the Building Biology guideline of 0.4 W/kg
Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.
Where This Falls on the Concern Scale
Study Details
Previous reports indicate that microwave-induced hyperthermia can impair learning and memory. Here, we report that preexposure to a single 20-min period of hyperthermia can produce thermal tolerance and, thereby, attenuate future physiological and behavioral reactions to heating. Because endogenous opioids have been implicated in thermoregulation and reactions to microwave exposure, we also determined how opioid receptor antagonism might modulate these effects.
In an initial experiment, rats were exposed daily, over 5 successive days, to 600-MHz microwaves (at...
Microwave exposure produced a reliable hyperthermia which was significantly lower (on Day 2) in rats...
Taken together, these data are consistent with the conclusions that 1) microwave-induced hyperthermia can cause a dose-dependent disruption of the normal discrimination between new and familiar objects, 2) physiological reactions to a single hyperthermic episode can produce a thermotolerance that expresses itself in both reduced levels of hyperthermia and attenuated behavioral disruptions following microwave exposure, and 3) opioid antagonism can partially reverse some of the behavioral effects of microwave-induced hyperthermia.
Show BibTeX
@article{ga_1998_thermal_tolerance_reduces_hyperthermiainduced_1203,
author = {Mickley GA and Cobb BL},
title = {Thermal tolerance reduces hyperthermia-induced disruption of working memory: a role for endogenous opiates?},
year = {1998},
url = {https://pubmed.ncbi.nlm.nih.gov/9618009/},
}