Genetic discovery offers clues for repairing damaged neural connections

I suppose your incompetent? doctor hasn't already provided the needed axon pathfinding protocols! 

• axon pathfinding (51 posts to February 2012)

AND YOU HAVEN'T FIRED THEM YET?

 Genetic discovery offers clues for repairing damaged neural connections

A new discovery by neuroscientists at Brown University's Carney Institute for Brain Science challenges long-held beliefs in neurobiology about how neurons extend axons to reach their targets.

Published in PNAS, the findings provide what the authors call a "genetic atlas" of neuronal development as well as a potential step forward for understanding how to repair broken neural connections in conditions such as stroke and spinal cord injury.

We discovered that during development, neurons turn on and off entire groups of genes that allow their axons to grow through different sections of their path. That's surprising." 

Alexander Jaworski, study author, associate professor of brain science, Carney Institute

Axons are critical components of neural wiring. During embryonic development, they shoot out from neurons like plant tendrils searching for light, traveling along intricate and sometimes long pathways to reach target cells. For example, the axon of a motor neuron that enables foot movement extends all the way to the foot from the base of the spine.

How are axons capable of making these connections with such precision? Until now, the conventional thinking was that because axons are so long and respond so rapidly to their environment, the guidance about where to grow next must come from the axon tip. 

A team of researchers in Jaworski's lab discovered a new twist: Axons are actually controlled by a genetic switch in the cell body of the neuron.

Prior to this study, researchers knew that part of the secret to an axon's long-distance travel is that they stop at intermediate waystations en route to their destination. As they pass through a waystation, axons pivot as needed to aim for the next one - a process called axon pathfinding.

To understand this process in more depth, the researchers focused on commissural neurons, which connect the left and right sides of the central nervous system. This specific neuron type is particularly useful to study because its axon makes a distinct, sharp change in direction as it crosses the spinal cord midline.