Examination of cerebral excitation patterns, fast and slow reactions in a visual oddball task

Abstract

  We investigated which of the frequency components of the electroencephalogram (EEG); beta band, shows chronological changes in the cerebral information processing during a visual oddball task. The fast and slow reactions were compared and analyzed to show factors of the delay in reaction time.

  Fifteen healthy subjects (all right-handed) were studied. In the oddball task, the subject was instructed to push a button with the right thumb as quickly as possible when the target stimulus from a computer display was perceived. The EEG was recorded from the scalp by 128 channels. The beta band (13 to 30 Hz) was isolated from the EEG and analyzed.

  The chronological changes of beta band in the left and right cerebral cortices were as follows. After the excitation from a visual stimulus reached the visual cortex, the excitation was transmitted to the temporal and the parietal association areas, and then from these association areas to the frontal association area. The activities of these pathways were occurred repetitively three times until a button was pushed. When the reaction time was delayed, the frequencies of excitation in the frontal association area, the parietal association area and the visual cortices of both cerebral cortices increased.

  Our data suggested that the repeated pathway indicated known visual information processing. The frontal association areas are an important area for cognitive function. Therefore the frontal association areas probably play an important role in decision-making for a fast reaction.