2005 Volume 3 Issue 2 Pages 59-67
This study was done to examine which of the frequency components of the EEG beta wave, shows chronological changes in cerebral information processing during a simple reaction task by image visual stimulus. Then the fast reaction and the slow reaction were compared and examined.
Seven healthy subjects（all right-handed）were studied. As the image stimulus, the subject was presented with images for 300 ms from a computer display. Each subject was instructed to push a button with the right thumb when he or she perceived the image stimulus. An EEG was recorded from the scalp by 128 channels, and it was separated into frequency bands of beta waves（13 to 30 Hz）and then analyzed. The brain potential distribution was image processed chronologically on a three-dimensional MRI image every 2 ms, and presented as excitation areas in the brain and was analyzed.
The chronological changes in the beta wave band in the left brain and the right brain were as follows: After excitation from the visual stimulus reached the visual cortex, the excitation was transmitted to the parietal association area and the temporal association area, and then from these two association areas to the frontal association area. This pathway was shown two times at onset. When the reaction time was delayed, the frequency of excitation in the frontal association area, the temporal association area and the visual cortex increased.
The results indicate that the frontal association area and the temporal association area probably play an important role in decision-making for a fast reaction.
