my nerves are bad to-night

In the late 1880s, Italian scientist Angelo Mosso built an intricate full-body balance and reported that mental activity tips the scales. Now, a modern-day version of Mosso’s “human circulation balance” backs him up…

Right after a two-second blip of either audio or audio and video, blood leaves the brain, as measured by a drop in force, Field and Inman found. This quick dip in blood volume, a phenomenon that’s also seen in functional MRI, may represent the brain preparing for work by shunting waste-ridden blood out via the jugular vein. Seconds after that, a surge of new blood enters the brain, increasing the force measured by the scale.

These changes in force were very small — about 0.005 newtons — and most prominent in the people who both listened to music and watched a video, Field says. It’s hard to calculate how much blood rushes into the brain with each mental task. To know that value, scientists would need to know the distance of the head from the lever’s fulcrum, which could be easily measured, and exactly where the blood came from, which is nearly impossible to know.

In his original experiments, Mosso found that tasks that required more mental energy made the brain heavier. Reading a page from a mathematics manual seemed to tip the balance more than reading a page from a newspaper. Strong emotions also tipped the scales: When a subject read a letter from an angry creditor, Mosso wrote, “the balance fell at once.”  read more

PHOTOGRAPH: Mike Hollingshead