Learning how neurons communicate.

• Position: Biochemistry - Brief Article

Researchers at the University of Texas Southwestern Medical Center at Dallas have discovered a biochemical pathway that helps describe how neurons in the brain and spinal cord form their connections. "By learning how nerve fibers grow and form connections in the embryonic brain and spinal cord, we may ultimately be able to determine how to coax nerves to regrow and regenerate," indicates Mark Henkemeyer, an assistant professor in the Center for Developmental Biology.

The research focuses on a specific group of receptors and ligands that are widely expressed in the developing nervous system. Normally, ligands produced by one cell bind to their corresponding receptor, which is expressed on target cells. This causes a change in the receptor, allowing it to transduce signals into the receiving cell. Although the body contains a vast array of different classes of receptors and ligands, Henkemeyer and his team have been working to learn how a particular group of such molecules--Eph receptors and ephrin ligands--communicate biochemical signals between two cells.

"We found that these molecules communicate important signals that guide the growing tips of embryonic nerve fibers [the axon growth cone] and, therefore, help form networks of neurons and synapses in the brain in a process called axon pathfinding," Henkemeyer explains. "We're trying to define the cellular and biochemical basis of how neurons can establish all these connections."

The entire circuitry of the brain and nervous system is controlled by this pathfinding, which leads to the formation of intricate and highly precise connections. "I like to view the brain as the amazing organic supercomputer. But what's most amazing is that, unlike the supercomputers that humans assemble with their hands, neural networks, which are much more...