Continuous Motion:

Valentin Dragoi, Ph.D., assistant professor of neurobiology and anatomy, Medical School and GSBS

Valentin Dragoi, Ph.D.

Understanding how the brain uses information to form and update visual images may someday help develop prostheses that can be implanted in the brain to assist visually impaired people.

Vision is truly moving pictures. “Indeed,” Dragoi said, “the world doesn’t sit still – trees move in the wind and birds fly across the sky. Our eyes also move, as we examine the world, to help us fixate on one part of the image and then the next, with a rapid eye movement in between. The brain itself is in continuous motion, even in the absence of sensory input – waves of ongoing neuronal activity sweep across the cortex in random motion. But how, with so much internal and external motion, could the brain build an efficient representation of the world and update the representation as new information is acquired?”

Research in Dragoi’s laboratory is aimed at understanding how individual neurons and networks in the visual cortex of animals construct a real-time internal representation of incoming stimuli and how image representations relate to visual behavior.

“We employ electrophysiological techniques that allow us to record simultaneously the activity of multiple neurons in the visual cortex of alert animals during specific behavioral tasks they have been trained to perform,” he said. “These experiments are complemented by computational models of network function to understand how neural circuits adapt to changes in input activity.”

The research has the potential to advance understanding of the mechanisms underlying visual perception and learning, as well as help develop implantable visual prostheses.

Dragoi started as a computer scientist with strong interests in artificial image processing systems. As he read more about how vision works, he “became amazed by the reliability with which visual perception operates,” he said. “What was most striking was that, despite the fact that most artificial devices are only able to function over a limited luminance range, animals and humans are able to rapidly adjust to large changes in luminance (for instance, although we are temporarily blind when walking from bright sunlight to a dark auditorium, we start seeing shapes and images within seconds).”