抄録
The effects of fractionated X-irradiation on the spontaneous electrical activity in the visual cortex were studied in four adult male rabbits with permanently implanted electrodes. Two of the rabbits received a dose of 300 R and two a dose of 1500 R, fractionated into 50 and 150R per day administered at semi-weekly intervals. The head, except for the region of brain, was shielded with a lead plate. The electrical activity was averaged with a CAT 400B. The obtained averaged electrocorticograms were classified into seven waves: δ2, δ1, θ, α, β1, β2 and β3 by means of an EEG frequency analyzer. The amplitude of the δ2, δ1, θ, α and β1 waves of the two animals irradiated with 1, 500 R gradually decreased with increasing doses during fractionated X-irradiation. The decreased value remained relatively constant throughout the observation period after the end of exposure. The two animals irradiated with 30O R did not show any definite changes in amplitude during and after fractionated irradiation. The results are discussed in reference to the findings of the previous study using photic stimulation.
