New Study Shows on How Brain Processes Visual Information

by VR Sreeraman on Aug 1 2007 6:21 PM

While it has for long been believed that vision is processed in the brain along circuits made up of neurons, researchers have now discovered a new way in which visual information is processed.

Scientists at Georgetown University Medical Center have found that visual signals also get processed when passed through the brain areas like propagating waves oscillating back and forth.

"What we found is that signals pass through brain areas like progressive waves, back and forth, a little bit like what fans do at baseball games," said Dr. Jian-young Wu, corresponding author of the study reported in the journal Neuron.

He said that just as the stadium wave is coordinated and travels through the crowd, a collective pattern emerges from the activities of millions of neurons in the visual areas.

"It simply makes sense that brain function is the result of large numbers of neurons working together," he said.

Dr. Wu says that the new findings challenge age-old notions about how the brain processes sensory information,

"One traditional model theorizes that neurons are hooked together into specific circuits. However, new imaging methods tell us that there are more than just circuits," he said.

The researchers visualized wave-like patterns in the brain cortex using a new method called voltage sensitive dye imaging. They used a special dye that binds to the membrane of neurons and changes colour when electrical potential passes along active neurons.

Dr. Wu says that finding waves during visual processing is an important step toward understanding how the brain processes sensory information.

This understanding, he says, has the potential to help scientists understand the abnormal waves that are generated in the brains of patients with Parkinson's disease and epilepsy, and how the mind fails when the brain of an Alzheimer's disease patient cannot properly organize population neuronal activity.

Dr. Wu, however, admits that further research is needed to understand both normal and abnormal waves in the human brain.

"Understanding how the brain handles these waves will provide further insight into the functioning of one of the most complex systems in the universe," he said.