EFFECTS OF LOW‐INTENSITY MICROWAVES ON ISOLATED NEURONS *

Surprisingly few studies of the effects of microwaves directly on nerve cells have been undertaken. Instead, most .of the evidence for or against a presumed neuronal effect has been extrapolated from studies of whole animals or from hypothetic models. With whole animal studies, considerable uncertainty exists as to dosimetry and specificity of effect a t the neuronal level. For modeling studies, serious questions often arise about the validity of the assumptions upon which the model is based. It seems to us, therefore, that isolated neuron preparations offer a useful approach in this area of investigation. In our laboratory, we have been utilizing ganglia from the marine gastropod Aplysia in studies of neuronal function for several years, and we are now using the same preparation to study the effects of microwaves on isolated nerve cells. In addition to the usual advantages of these ganglia for neural studies,’ they are much smaller in size ( I or 2 mm in diameter) than even the shortest length microwave we employ. This factor is extremely useful with respect to dosimetry and instrumentation. Our experimental approach consists of placing an Aplysiu ganglion within a microwave stripline and employing intracellular glass microelectrodes to record the electric activity of individual neurons before, during, and after the ganglion is irradiated. In addition to monitoring the incident and reflected microwave power levels, we have carefully recorded, and run controls for, ganglionic temperature. We have noted definite effects on the firing patterns of Aplysiu neurons at absorbed microwave power levels that are below what human brain cells would be exposed to a t the accepted American “safety” level (10 mW/cc). In large part, these effects are attributable to slight ganglionic warming, but in some cases, we have also found effects that are not accompanied by, or not reproduced by, ganglionic warming.