Ralph M. Siegel

IN MEMORIAM: 1959-2011

Uncovering the neural processes of vision

How We See the World

We drop a coin near our right foot and bend down to pick it up. But how does our hand know just how far it needs to move to the right to reach the coin? How are we able to recognize the shape so we can bend our fingers exactly the right way to grasp the coin? And how does our brain know where to find the edge so we can flip it?

Vision, rather than being a process of projecting an image somewhere in our brain, is a complicated process involving multiple neural pathways. We look at a tree and the color green is processed in one area of the brain, the shape in another, and the movement of its branches dancing in the wind in yet another area. Vision takes place neither in the eyes or the brain, but rather is the result of a blending together of multiple streams of information that reveal themselves as a stable image.

"There is no movie screen in our head," says Ralph M. Siegel, professor of neuroscience, whose research focuses on identifying the neurological underpinnings of vision. "Instead vision is a matter of the brain pulling together information from different processing streams to present a stable image of the world, yet it never has a stable image itself."

The ultimate goal of Siegel’s research is to provide an understanding of visual perception that will lead to applications to assist people who suffer from neurological damage and visual motor processing disorders.

In his research, Siegel specifically centers on the intermediate process that takes place in the cortex where multiple streams of information are brought together to guide motor action. What Siegel and his co-researchers have found is that process appears to be a fluid one where neurons make new connections and relationships every time they are presented with input. That instead of a mapped process where neurons consistently establish the same pattern of connections when presented with the same or similar stimuli, they establish new relationships – yet still present us with a stable image of the world. Their research additionally has revealed that in the process of vision and motor action, cells apparently also report where our hands are in relation to the object being viewed.

"The brain is taking in information in bits and pieces, processing it in different areas, but we do not see the world as a set of strange components,” notes Siegel. “We don't have a vision of the world of things wriggling around, instead we see the world as stable and where we are in the world. What really matters is not what is outside but what is inside our head."

Biography

Ralph M. Siegel earned his B.S. in physics and his Ph.D. in physiology from McGill University in Montreal. He performed his post-doctoral research at The Salk Institute for Biological Studies in La Jolla, CA, where he trained in the study of the inferior lobe, learning about its anatomy, physiology and the roles it plays in brain function. He then moved to The Rockefeller University where he worked with Nobel Laureate Torsten Wiesel, continuing his studies in brain research. He joined the Center for Molecular and Behavioral Neuroscience in 1989. Next year he will publish his first book, "Another Day in the Monkey's Brain," with Oxford University Press.

Selected Publications

• Another Day in the Monkey's Brain, Oxford University Press, Forthcoming
• Functional Organization of Temporal Frequency Selectivity in Primate Visual Cortex, Cerebral Cortex, December 3, 2007
• A Functional Architecture of Optic Flow in the Inferior Parietal Lobule of the Behaving Monkey, PLoS ONE, February 7, 2007
• Attentional Modulation of Receptive Field Structure in Area 7a of the Behaving Monkey, Cerebral Cortex, October 31, 2006
• Spatiotemporal Dynamics of the Functional Architecture for Gain Fields in Inferior Parietal Lobule of Behaving Monkey, Cerebral Cortex, April 7, 2006
• Functional Architecture of Spatial Attention in the Parietal Cortex of Behaving Monkey, Journal of Neuroscience, May 25, 2005
• Three-dimensional Structure-from-motion Selectivity in the Anterior Superior Temporal Polysensory Area, STPa, of the Behaving Monkey, Cerebral Cortex, January 12, 2005