On a crowded bus is a young man with shaved head, pierced ears and nose, silver chains. Two snakes slither down his forearms, their heads and forked tongues visible thalamic neurons have been observed to fire, not only at similar rates of about 40 Hz, but in a remarkably coordinated pattern called gamma oscillation. They fire precisely in rhythm and on the back of his hands. I wonder about what this image can mean to him, but remain silent.

Later, outside a coffeehouse, a friend displays his new tattoo, its deep green Art Deco design of angular lines still healing on his forearms. I tell himabout the snakes. He replies, "You should have asked him. People like to talk about their tattoos."