Thinking Hard Improves Blood Circulation in Your Brain

In my lab, we work on biometrics. These measurements include electrophysiological measurements, as well as measuring force and length. We also measure brain activity, which is the topic of my talk today. Our brain shows little activity during our casual, everyday movements. This makes sense, doesn't it? If you had to consciously think about every step while walking—"put out my right foot, shift my weight onto it, push off the ground with the ball of my right foot, then put out my left foot..."—you would miss your train. Walking is almost a reflex. Now, can you tap a three-beat rhythm with your right hand and a two-beat rhythm with your left hand simultaneously? People who play the piano can probably do it. It's like playing triplets. People who play the drums can likely do it as well. For these individuals, tapping a three-beat rhythm with the right hand and a two-beat rhythm with the left hand requires very little cerebral activity. However, those who don't play the piano or drums cannot perform this polyrhythm without concentrating very hard. This is where a tool called optical topography, shown in Figure 1 below, comes in. By using it to measure blood flow in the brain from the scalp, we can see that the frontal lobe, the area responsible for volition, becomes active. Please look at Figure 2 below. This shows the state of activity when tapping a three-beat rhythm with both the right and left hands. There is almost no activity. This is because it is a simple action. However, when tapping a three-beat rhythm with the right hand and a two-beat rhythm with the left, the person has to think hard about how to move their hands, causing the frontal lobe to become active, as shown in Figure 3 below. But after practicing this movement for about a week, they get used to it, and the frontal lobe no longer shows activity. Their hands begin to move as a reflex, just like walking. Until recently, measuring brain function was limited to methods such as electroencephalography (EEG), magnetoencephalography (MEG), fMRI (functional magnetic resonance imaging), and PET (positron emission tomography). However, as better measurement devices are developed, we will be able to measure a wider variety of functions.