Time Travel in the Brain
What are you doing when you aren’t doing anything at all? If you said “nothing,” then you have just passed a test in logic and flunked a test in neuroscience. When people perform mental tasks–adding numbers, comparing shapes, identifying faces–different areas of their brains become active, and brain scans show these active areas as brightly colored squares on an otherwise dull gray background. But researchers have recently discovered that when these areas of our brains light up, other areas go dark. This dark network (which comprises regions in the frontal, parietal and medial temporal lobes) is off when we seem to be on, and on when we seem to be off. If you climbed into an MRI machine and lay there quietly, waiting for instructions from a technician, the dark network would be as active as a beehive. But the moment your instructions arrived and your task began, the bees would freeze and the network would fall silent. When we appear to be doing nothing, we are clearly doing something. But what?
The answer, it seems, is time travel.