Study type: Medical/biological study (experimental study)

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

Published in: Physiol Behav 1994; 55 (6): 1029-1038

Aim of study (acc. to author)

To study the effects of hyperthermia on working memory, the ability of rats to discriminate between objects following microwave exposure was recorded. Furthermore, the expression of the early proto-oncogene c-fos in the brain was used as a tool to indicate which brain regions were activated or possibly damaged by microwave exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 600 MHz
Modulation type: CW
Exposure duration: 20 min
  • SAR: 10 mW/g mean (whole body) (9.3 W/kg, 8.5 W/kg, 5 W/kg, 1 W/kg and 0.1 W/kg)

Exposure 1

Main characteristics
Frequency 600 MHz
Type
Charakteristic
Polarization
Exposure duration 20 min
Modulation
Modulation type CW
Exposure setup
Exposure source
  • 90? corner reflector
Distance between exposed object and exposure source 1 m
Chamber Anechoic chamber maintained at 24?C
Setup rats were irradiated individually in 3 mm thick plastic restraint holders
Additional info The rats remained for 20 min in their home cages (cage control). Electric field was parallel to the long axis of the rats.
Parameters
Measurand Value Type Method Mass Remarks
SAR 10 mW/g mean determined by power loss whole body 9.3 W/kg, 8.5 W/kg, 5 W/kg, 1 W/kg and 0.1 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Animals irradiated by more than 5 W/kg exhibited hyperthermia when compared to nonirradiated control animals. Normothermic control rats (sham-irradiated rats and rats exposed to 0.1 W/kg) showed a distinct preference for the new object although other microwave-irradiated animals with brain hyperthermia (1, 5, 8.5, 9.3, 10 W/kg) did not. These findings suggest a disruption of the memory of the previously explored object.
Microwave hyperthermia evoked significant expression of the early proto-oncogene c-fos in periventricular strata, hypothalamic nuclei, amygdala, and several areas of the cortex. The pattern of c-fos expression may suggest candidate brain nuclei that mediate the behavioral changes observed.
These results indicate that performance on a putative working memory task may be disrupted by a sufficiently intense microwave-induced hyperthermia.

Study character:

Study funded by