INCREASE IN THE CALCIUM LEVEL FOLLOWING ANODAL POLARIZATION IN THE RAT-BRAIN

The accumulation of calcium ions (Ca) was examined in the rat brain by means of Ca-45 autoradiography following the application of a weak an odal direct current to the surface of the sensorimotor cortex. Repetit ion of the anodal polarization with 3.0 mu A for 30 min caused more Ca to accumulate in the cerebral cortex. The degree and extent of accumu lation was greater in the hemisphere ipsilateral to the polarization t han in the other. Accumulation was also noted in the hippocampus and t halamus. Ca accumulation was detected after 24 h and it remained virtu ally constant up to 72 h after the last polarization. The results sugg est that a long-lasting disturbance of Ca homeostasis is involved in t he cortical plastic changes seen following anodal polarization.