Prof. Barry Van Veen wearing an electrode net used to monitor brain activity via EEG signals. | Credit: Nick Berard

Indulging in daydream distracts one’s attention from the present and as real as it may seem, its path through the brain runs opposite reality.

With an aim to identify discrete neural circuits, researchers at the University of Wisconsin–Madison have been able to track electrical activity in the brains of people who alternately imagined scenes or watched videos and find that reality and imagination flow in opposite directions in the brain.

“A really important problem in brain research is understanding how different parts of the brain are functionally connected. What areas are interacting? What is the direction of communication?” says Barry Van Veen, a UW-Madison professor of electrical and computer engineering. “We know that the brain does not function as a set of independent areas, but as a network of specialized areas that collaborate.”

The study was published in the journal NeuroImage in joint effort with Giulio Tononi, a UW-Madison psychiatry professor and neuroscientist, Daniela Dentico, a scientist at UW–Madison’s Waisman Center, and collaborators from the University of Liege in Belgium.

They hope the study could eventually be a gateway to developing new tools to help what happens in the brain during sleep. Barry Van Veen hopes to apply the study’s new methods to understand how the brain uses networks to encode short-term memory.

When one indulges in imagination, there is an increase in the flow of information from the parietal lobe of the brain – the lobe at the top of the head that includes areas concerned with the reception and correlation of sensory information – to the occipital lobe – the rearmost lobe. In short, the flow of information from a higher-order region to a lower-order

However, when visual information is taken in by the eyes, it tends to flow from the occipital lobe up to the parietal lobe.

“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,” says Van Veen. “I think this is really a new theme that had not been explored.”

The researchers exploit the power of electroencephalography (EEG) which uses scalp to measure electrical activity in different parts of the brain – to discriminate between different parts of the brain’s network. EEG records activities in the brain that are not necessarily related to a particular process researchers want to study.

To focus on a set of target circuits, the researchers asked the participants to watch short video clips before trying to replay the action from memory in their heads, while others were asked to imagine traveling on a magic bicycle — focusing on the details of shapes, colors and textures — before watching a short video of silent nature scenes.

Using an algorithm Van Veen developed to analyse the detailed EEG data, the researchers were able to compile strong evidence of the directional flow of information.

“We were very interested in seeing if our signal-processing methods were sensitive enough to discriminate between these conditions,” says Van Veen, whose work is supported by the National Institute of Biomedical Imaging and Bioengineering. “These types of demonstrations are important for gaining confidence in new tools.”