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.
|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.|
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.