DYNAMIC ACTIVITIES OF THE FRONTAL ASSOCIATION CORTEX IN CALCULATING AND THINKING

We found 5-7 Hz magnetic theta waves in the frontal association cortex of adult human subjects during calculation and musical imagination by using 37-channel SQUID gradiometers. Simultaneous recording from the left and right cerebral hemispheres with two sets of 37-channel gradio meters revealed that the theta activity appeared in a waxing and wanin g manner in the frontal cortices of both hemispheres during the mental exercises. Electrical current dipoles for the theta waves were estima ted to occur repeatedly and scatteringly in various parts of the front al lobes of both hemispheres during continuous and intense mental exer cises for 2 min. The results suggest a dynamic mode of activities in t he frontal association cortex during mental effort such as calculating and thinking.