For years, the brain has been thought of as a biological computer that processes information through traditional circuits, whereby data zips straight from one cell to another.
While that model is still accurate, a new study led by Salk Institute shows that there's also a second, very different way that the brain parses information; it’s similar to ocean waves, according to scientists. The findings were published in Science Advances on April 22.
According to the traditional model of the brain, the sensory information, like the sight of a light or the sound of a bell -- have revolved around information being detected by specialized brain cells and then shuttled from one neuron to the next. This model, however, couldn't explain how a single sensory cell can react so differently to the same thing under different conditions. A cell, for instance, might become activated in response to a quick flash of light when a man is particularly alert, but will remain inactive in response to the same light if the man’s attention is focused on something else.
The team likens the new understanding to wave-particle duality in physics and chemistry. In some situations, light behaves as if it is a particle (also known as a photon). In other situations, it behaves as if it is a wave.
“The process is comparable to waves of activity across many neighboring cells, with alternating peaks and troughs of activation -- like ocean waves. When these waves are being simultaneously generated in different places in the brain, they inevitably crash into one another. If two peaks of activity meet, they generate an even higher activity, while if a trough of low activity meets a peak, it might cancel it out. This process is called wave interference,” explained Thomas Albright, director of Salk's Vision Center Laboratory.
To test their mathematical model of how neural waves occur in the brain, the team designed an accompanying visual experiment. Two people were asked to detect a thin faint line located on a screen and flanked by other light patterns. How well the people performed this task, the researchers found, depended on where the probe was. The ability to detect the probe was elevated at some locations and depressed at other locations, forming a spatial wave predicted by the model.