In a nutshell: When we see something in motion, its direction of movement influences the movement of corresponding waves in brain activity.

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Brain activity ebbs and flows like ocean waves during a tropical storm. The turbulent waves of activity form micro patterns even when we’re sleeping or under anaesthesia, but how these patterns relate to what we’re currently seeing and experiencing is not completely understood.

Brain Function CoE researchers Rory Townsend, Pulin Gong and Paul Martin, together with colleagues at the University of Sydney and University College London, wanted to see what these wave patterns look like in the visual areas of the brain while we’re watching moving objects. The team showed marmosets a series of moving patterns on a computer screen. They rotated the patterns – either circular white dots or sets of parallel lines – by 90 degrees until the marmosets had seen them 100 times in all four cardinal directions.

Using methods for analysing turbulence patterns in gases and liquids, the team found that the direction in which the patterns moved across the screen altered the direction of the corresponding brain waves in areas of the brain that respond to visual information.

This discovery marks the first time that the movement direction of brain waves has been directly linked to movement in the environment. “These waves were not previously detected,” explains Gong, “because we normally average brain activity across many repetitions of the experiment. This averaging process makes the responses easier to interpret, but we found that it also removes all of the interesting wave activity.”

The team speculates that these moving waves have a specific role in information processing in the brain.

Next steps:
The team plans to look for similar wave patterns in different brain regions and is developing models to predict what happens when the wave patterns interact – such as when many objects are moving in different directions. They are also developing a computational toolbox to make their pattern-detection methods available to other researchers.

Townsend, R., Solomon, S. S., Martin, P. R., Solomon, S. G., & Gong, P. (2017). Visual motion discrimination by propagating patterns in primate cerebral cortex. Journal of Neuroscience, doi: 10.1523/JNEUROSCI.1538-17.2017

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