"I am enough of an artist to draw freely upon my imagination," Albert Einstein once said. "Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world."

In fact, imagination may be our greatest skill. Neuroscientists and psychologists used to regard our ability to imagine fictional scenarios, people and objects as mere mental fluff. Now imagination is recognized as playing a central role in human thought, from planning and creativity to memory and problem-solving. It protects our mental health and may even be the fragile foundation upon which human society is built.

We all imagine, or daydream, and as real as the daydream seems, its path through our brains run opposite to reality. Understanding how different parts of the brain are functionally connected, what areas are interacting and what is the direction of communication are important considerations — or perhaps problems to be solved — in brain research.

In an effort to discern discrete circuits, researchers studied brainwaves to determine how interpretation of reality differs from imaginary thought in the human brain. Barry Van Veen, a professor of electrical and computer engineering at the University of Wisconsin-Madison, and his team focused on researching how the signals were transmitted between neurons.

Van Veen and his team tracked electrical activity in the brains of people who alternately imagined scenes or watched videos, and they determined that our brainwaves react differently when we are daydreaming versus when we are thinking about reality, as well as the difference between when we are asleep versus when we are awake.

During imagination, the researchers found an increase in the flow of information from the parietal lobe of the brain to the occipital lobe — from a higher-order region that combines inputs from several of the senses out to a lower-order region. In contrast, visual information taken in by the eyes tends to flow from the occipital lobe, which makes up much of the brain's visual cortex, "up" to the parietal lobe.

The researchers approached the study as an opportunity to test the power of electroencephalography (EEG), which uses sensors on the scalp to measure underlying electrical activity, to discriminate between different parts of the brain's network.

Van Veen, along 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, have published their results in the journal NeuroImage.

Their work could lead to the development of new tools to help Tononi untangle what happens in the brain during sleep and dreaming, while Van Veen hopes to apply the study's new methods to understand how the brain uses networks to encode short-term memory.