How your brain remembers the future

IT'S like remembering the future. Our brain generates predictions of likely visual inputs so it can focus on dealing with the unexpected.

Predictable sights trigger less brain activity than unfamiliar stimuli, bolstering the view that the brain is not merely reactive, but generates predictions based on the recent past. "The brain expects to see things and really just wants to confirm it now and again," says Lars Muckli at the University of Glasgow, UK.

He and Arjen Alink at the Max Planck Institute for Brain Research in Frankfurt, Germany, asked 12 volunteers to focus on a cross on a screen, above and below which bars flashed on and off to create the illusion of movement. To test a predictable stimulus, a third bar would appear in a position timed to fit in with the illusion of smooth movement. For the unpredictable stimulus it would appear out of sync. fMRI scans showed that the unpredictable stimulus increased the activity in parts of the brain which deal with the earliest stages of visual processing (Journal of Neuroscience, vol 30, p 2960).

The finding supports the "Bayesian brain" theory, which sees the brain as making predictions about the world which it updates when new information comes in.