Mickley G A, Cobb B L, Mason P A, Farrell S
Radiofrequency Radiation Division (AL/OER), Armstrong Laboratory, Brooks AFB, TX 78235-5324.
Physiol Behav. 1994 Jun;55(6):1029-38. doi: 10.1016/0031-9384(94)90384-0.
To discern the effects of hyperthermia on working memory, we recorded the ability of rats to discriminate between objects following microwave radiation exposure. Memory changes were evaluated by measuring relative exploration time of a familiar vs. a new stimulus object. A subject that extensively reexplores a stimulus with which it has previous experience is presumed to exhibit memory loss associated with that object. Between training and testing, rats were exposed to various doses of microwave radiation, were sham irradiated, or remained in their home cage. Brain (dural) and rectal temperatures were recorded. To discern brain regions activated or possibly damaged by microwave exposure, we also used immunocytochemistry techniques to identify sites of c-fos protein expression in the brains of several irradiated/sham-irradiated subjects. Rats exposed to > 5 W/kg exhibited hyperthermia when compared to nonirradiated controls. Normothermic control subjects (sham-irradiated rats and rats exposed to 0.1 W/kg) showed a distinct preference for the new object although other microwave-exposed rats (1, 5, 8.5, 9.3, 10 W/kg) did not. Microwave hyperthermia evoked prominent c-fos expression in periventricular strata, hypothalamic nuclei, amygdala, and several areas of the cortex. 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.
为了探究高温对工作记忆的影响，我们记录了大鼠在微波辐射暴露后区分物体的能力。通过测量熟悉刺激物体与新刺激物体的相对探索时间来评估记忆变化。如果一个实验对象对其先前经历过的刺激进行大量重新探索，则推测该对象表现出与该物体相关的记忆丧失。在训练和测试之间，将大鼠暴露于不同剂量的微波辐射、假照射或置于其饲养笼中。记录大脑（硬脑膜）和直肠温度。为了辨别微波暴露激活或可能损伤的脑区，我们还使用免疫细胞化学技术来鉴定几只接受照射/假照射的实验对象大脑中c-fos蛋白表达的位点。与未照射的对照组相比，暴露于>5W/kg的大鼠出现了高温。体温正常的对照实验对象（假照射大鼠和暴露于0.1W/kg的大鼠）对新物体表现出明显的偏好，而其他接受微波照射的大鼠（1、5、8.5、9.3、10W/kg）则没有。微波诱导的高温在脑室周围层、下丘脑核、杏仁核和皮质的几个区域引起了显著的c-fos表达。这些数据表明，足够强烈的微波诱导高温可能会扰乱一项假定的工作记忆任务的表现。早期原癌基因c-fos的表达模式可能提示了介导我们所观察到的行为变化的候选脑核。
