Classification subject effects using changes in cerebral blood flow on the Stroop test.

Functional near-infrared spectroscopy (fNIRS) is often used as a diagnostic method for mental illness, because the average patterns of changes in cerebral blood flow vary between such patients and healthy subjects. In addition, indoor environments and psychology alter the average patterns of changes in cerebral blood flow. These observations suggest that it may be possible to classify healthy subjects into different groups according to certain characteristics. The accuracy of fNIRS should be improved once it becomes possible to automatically determine the key factors affecting fNIRS data. The present study was performed first to determine whether there are differences in fNIRS data when the test subjects are classified into groups based on the scores related to task performances and questionnaires, and to determine whether there are differences in score when the test subjects are classified into groups based on fNIRS data. Differences were observed in fNIRS data between groups when the subjects were classified based on incorrect answers on the questionnaire and their degree of fatigue. In addition, there were differences in score between groups when the subjects were classified according to fNIRS data. These results suggested that subjects can be classified into groups automatically based on scores related to both task performance and fNIRS data.

Measurements of right / left hemisphere activation using functional near-infrared spectroscopy during incongruent Stroop test.

The human brain automatically processes information at multiple sites when recognizing various types of information at the same time, such as color, shape, etc. Cognitive conflict may occur when conflicting information is recognized at the same time. Functional near-infrared spectroscopy (fNIRS) is often used to examine the brain activity associated with this phenomenon. To examine activation of the visual system, we measured brain activity in the right / left hemispheres during cognitive conflict in the Stroop test. Consistent with the results reported previously by Ehlis, the brain activity in the near inferior-frontal gyrus of the left hemisphere was increased during the incongruent task. The brain activity also increased in the near inferior-frontal gyrus of the right hemisphere during the incongruent task. These results indicated that fNIRS can be used to detect brain activity in the inferior-frontal gyrus of the right / left hemispheres during the Stroop test.