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Disruption of a putative working memory task and selective expression of brain c-fos following microwave-induced hyperthermia

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Mickley GA, Cobb BL, Mason PA, Farrell S · 1994

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Microwave radiation disrupted memory in rats at SAR levels of 1-10 W/kg, comparable to intensive cell phone use.

Plain English Summary

Summary written for general audiences

Researchers exposed rats to microwave radiation at different power levels and tested their ability to recognize familiar objects versus new ones. Rats exposed to higher levels (above 5 W/kg) showed memory problems and couldn't distinguish between familiar and new objects, while unexposed rats could. The study also found that microwave exposure activated stress response genes in key brain regions including the hypothalamus and amygdala.

Why This Matters

This 1994 study provides important evidence that microwave radiation can disrupt working memory through thermal effects on the brain. What makes this research particularly significant is that it identified specific brain regions affected by microwave exposure, including the hypothalamus and amygdala - areas critical for memory formation and emotional processing. The exposure levels that caused memory disruption (1-10 W/kg SAR) are within the range of what modern devices can produce during heavy use. While this study focused on thermal effects from high-intensity exposure, it demonstrates that microwave radiation can indeed alter brain function and memory performance. The researchers' use of c-fos protein expression as a biomarker also revealed that even when behavioral changes weren't obvious, the brain was still responding to the radiation exposure at a cellular level.

Exposure Details

SAR
0.1 , > 5 , 1, 5, 8.5, 9.3, 10 W/kg

Where This Falls on the Concern Scale

Study Exposure Level in ContextStudy Exposure Level in ContextThis study: 0.1 , > 5 , 1, 5, 8.5, 9.3, 10 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern rangeFCC limit is 16x higher than this level

Study Details

To study the disruption of a putative working memory task and selective expression of brain c-fos following microwave-induced hyperthermia

To discern the effects of hyperthermia on working memory, we recorded the ability of rats to discrim...

Rats exposed to > 5 W/kg exhibited hyperthermia when compared to nonirradiated controls. Normothermi...

These data suggest that performance on a putative working memory task may be disrupted by a sufficiently intense microwave-induced hyperthermia. The pattern of expression of the early proto-oncogene c-fos may suggest candidate brain nuclei that mediate the behavioral changes we observed.

Cite This Study
Mickley GA, Cobb BL, Mason PA, Farrell S (1994). Disruption of a putative working memory task and selective expression of brain c-fos following microwave-induced hyperthermia Physiol Behav 55(6):1029-1038, 1994.
Show BibTeX
@article{ga_1994_disruption_of_a_putative_1202,
  author = {Mickley GA and Cobb BL and Mason PA and Farrell S},
  title = {Disruption of a putative working memory task and selective expression of brain c-fos following microwave-induced hyperthermia},
  year = {1994},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/8047568/},
}
PubMed: 8047568

Cited By (42 papers)

Quick Questions About This Study

Yes, a 1994 study found that rats exposed to microwave radiation above 5 W/kg could not distinguish between familiar and new objects, indicating working memory disruption. Lower exposures (0.1 W/kg) did not affect memory performance, suggesting a threshold effect for cognitive impairment.
Research shows microwave-induced hyperthermia triggers prominent c-fos gene expression in critical brain regions including the hypothalamus, amygdala, and cortex. This stress response gene activation may explain the observed behavioral and memory changes from microwave exposure.
Studies demonstrate that microwave radiation exposure above 5 W/kg causes hyperthermia (elevated body temperature) in rats. Lower power levels of 0.1 W/kg and 1 W/kg did not produce significant temperature increases compared to unexposed control animals.
Microwave hyperthermia specifically activates c-fos expression in periventricular areas, hypothalamic nuclei, amygdala, and multiple cortical regions. These brain areas are involved in stress response, memory formation, and emotional processing, explaining the observed cognitive effects.
Microwave radiation at power levels of 5 W/kg and above disrupts object recognition memory in rats. While control animals could distinguish familiar from novel objects, microwave-exposed rats lost this ability, indicating impaired working memory function.