On the Brink of Chaos: Physicists Find Phase Transition in Visual Cortex

Russell Cothren

Woodrow Shew, University of Arkansas

FAYETTEVILLE, Ark. — Physicists have found that intense visual input forces the brain into a brief moment of chaos, but the visual cortex spontaneously returns the brain to its optimal function.

The finding advances fundamental understanding of how a healthy visual system processes information, said Woodrow Shew, an assistant professor of physics at the University of Arkansas.

“Our eyes and brain adapt and adjust to changing visual input, which is essential to our ability to see,” Shew said. “We studied how adaptation changes the brain and were surprised to find that adaptation ‘tunes’ the brain to a special mode of operation, called criticality.”

Shew and U of A graduate student Wesley Clawson, working with physicists in Ralf Wessel’s lab at Washington University in St. Louis, published their findings in the journal Nature Physics.

When operating at criticality, Shew said, the brain is poised at the brink between order and disorder, just like the boundary between phases of matter in physical systems. An example is the boundary between water and steam, Shew said.

 “This is the first study that shows these two things are intimately related,” Shew said. “It is amazing that the brain seems to do the best job of processing visual information at criticality.”

Shew, a neurophysicist, focuses his research on how the brain processes information.

“My research is a hybrid of physics and neuroscience,” Shew said. “I’m interested in how a network of neurons processes information. Neurons are simple and interact according to simple rules. When amazingly complex phenomena, such as perception and behavior emerge from such simple interactions, it appeals to a physicist.”

The National Science Foundation and the Whitehall Foundation funded the research.

About the University of Arkansas: The University of Arkansas provides an internationally competitive education for undergraduate and graduate students in more than 200 academic programs. The university contributes new knowledge, economic development, basic and applied research, and creative activity while also providing service to academic and professional disciplines. The Carnegie Foundation classifies the University of Arkansas among only 2 percent of universities in America that have the highest level of research activity. U.S. News & World Report ranks the University of Arkansas among its top American public research universities. Founded in 1871, the University of Arkansas comprises 10 colleges and schools and maintains a low student-to-faculty ratio that promotes personal attention and close mentoring.