March 8, 2001—Researchers have developed a powerful screening
method to identify genes that produce proteins that guide the
wiring of the trillions of connections in the mammalian brain.
The technique enables scientists to identify new genes and to
determine which genes are responsible for defects in brain
wiring that are observed during development. The scientists
believe that this technique is likely to accelerate the
discovery of new molecules involved in axon guidance. Neurons
wire themselves into networks by extending cable-like axons that
grow toward specific targets in the nervous system. An axon’s
path toward a target neuron is steered by growth cones in the
tip of the axon that receive cues about the best path to follow
from chemical attractants and repellents secreted by cells in
the nervous system. These attractants and repellents are
collectively called axon guidance molecules. In an article
published in the March 8, 2001, issue of Nature, researchers led
by Howard Hughes Medical Institute investi