Daydreaming, reality run in opposite directions

While tracking brain activity in people who imagined scenes or watched videos, researchers have discovered that as people daydream, its path through the brain runs opposite reality.

This could lead to the development of new tools to help untangle what happens in the brain during sleep and dreaming.

"There seems to be a lot in our brains and animal brains that is directional; that neural signals move in a particular direction, then stop and start somewhere else. I think this is really a new theme that had not been explored," said Barry Van Veen, professor of electrical and computer engineering at University of Wisconsin-Madison.

To zero in on a set of target circuits, the researchers asked their subjects to watch short video clips before trying to replay the action from memory in their heads.

Others were asked to imagine traveling on a magic bicycle - focusing on the details of shapes, colours and textures - before watching a short video of silent nature scenes.

Using an algorithm, researchers were able to compile strong evidence of the directional flow of information.

The team now plans to understand how the brain uses networks to encode short-term memory.

The paper was published in the journal NeuroImage.