Crosstalk between motor (shown in green) and sensory (shown in red) nerves ensures that the two different types of neurons join up after they emerge from the spinal cord either sensory or motor axons. (Source: Benjamin W. Gallarda and Shane E. Andrews, Salk Institute for Biological Studies)

In a study, published in Science, scientists at the Salk Institute for Biological Studies report that constant crosstalk between growing sensory and motor neurons keeps them on track. During embryonic development, nerve cells hesitantly extend tentacle-like protrusions called axons. Growth cones, small enlargements at the axons tip, actively search their local environment for chemical cues that guide them to their target. One such cue comes from a class of molecules called ephrins, which repel cells carrying Eph proteins.

The traditional view was that growth cones studded with Eph proteins search their environments for ephrins, which take on the role of ligands. The Salk researchers discovered that neurons not only carry both types of proteins, but that the role of ephrins and Ephs can change as well.

This article was published in Drug Discovery & Development magazine: Vol. 11, No. 5, May, 2008, pp. 18.