Development of a new method for measuring higher brain function - integrated measuring system by fMRI and MEG -

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The aim of this study is to establish a new integrated measuring system by fMRI, MEG and NIRS for evaluation of higher brain function. First, activated BOLD signals were observed during electrostimulation on bilateral median nerves by fMRI. Distributions of activated BOLD signals were evaluated in the three conditions, no delay, 30 msec delay and 100 msec delay. As a result, the smallest activated area was observed at the primary sensory area in the 30 msec delay condition. A MEG study revealed that no waves at 76 msec were observed in the 30 msec delay condition. Second, it was evaluated how the brain functions during loss-resulting or tie-resulting pursuant paper-rock-scissors with the dominant or non-dominant hands, using a 3-tesla functional MRI in normal right-handed subjects. Interestingly, the right SMA was activated more strongly during tie-resulting pursuant paper-rock-scissors with the left hand, while the left SMA was activated more strongly during loss-resulting pursuant paper-rock-scissors with the left hand. These findings suggest that the left SMA might be associated with inhibition of stereotypical performance and monitoring of conflict in the subject's mind. Last, we evaluated changes in blood concentration of hemoglobin by NIRS in the patients with severe carotid arterial stenosis before and after surgery. Before surgery, an evident elevation of blood concentration of hemoglobin was observed at the periprimary hand motor area during hand grasp task, although it disappeared after surgery. Our study revealed that further investigation is required to clarify more detailed higher brain functions, and for the achievement of this goal, it was especially important to compare the distributions of activated brain area by between fMRI and MEG during electrostimulation on bilateral median nerves.