Presentation: New Perspectives on the Role of Activity in Development of the Visual Nervous System

Speaker: Leo M. Chalupa, professor and chair, Section of Neurobiology, Physiology and Behavior

Symposium date and time: 2:30 p.m. to 5:40 p.m., Monday, Feb. 17.

Symposium name: Neuroinformatics: Genes to Behavior

Early in development, light-detecting cells in the retina show waves of activity long before the eyes are exposed to light. At the same time, axons of the optic nerve grow from the eye into the brain and form layered structures on each side of the brain called the lateral geniculate nuclei or LGN. Neuroscientists currently think that the waves of spontaneous activity somehow "instruct" the formation of segregated and left and right eye projections to the LGN, because if the activity in the retina is blocked, the connections to the brain do not develop.

Researchers led by Leo Chalupa, professor of neurobiology, physiology and behavior at the University of California, Davis, are challenging this view of brain development. Using an antibody coupled to a nerve toxin, they have stopped the activity of some of the cells in the retina. The light-detecting cells still show spontaneous activity, but in a random rather than a normal wave-like pattern. But the axons of the optic nerve still grow into the brain normally and form normal layered LGN structures.

The results show that neuronal activity in the eye permits the LGN to develop, but does not tell it how to develop, Chalupa said. The findings represent a major shift in the field, he said.