Talk:Axonal growth and guidance

Suggestion for introduction

Hi, it looks like this article is coming along very nicely. I'd like to make a suggestion for the introduction that might make it accessible to a larger group of readers, by helping to give the reader a mental picture of the process. Here is what I have in mind:

Brain function depends critically on precisely specified patterns of wiring between neurons, but setting up a wiring pattern is an extraordinarily challenging problem. In order to reach their targets, axons are often required to extend to distant regions of the brain or body, traveling through several distinct types of tissue. They do this by making use of chemical guidance cues.

Axonal pathfinding is implemented by a type of structure called a growth cone, which looks like a sort of blob at the tip of the growing axon, with numerous tiny fingers called filopodia extending from it. These filopodia are covered with chemical sensors. Each axon uses a distinctive array of sensors, specified by its gene expression pattern. Some types of sensors cause a filopodium to stick to surfaces that contain specific chemicals and then contract, pulling the growth cone toward the sticking point. Other types of sensors cause the filodpodium to contract without sticking, thereby encouraging the growth cone to move in the opposite direction. The sum of these forces determines the direction in which the axon extends. The net result is that axons are drawn toward concentration gradients of some chemicals and away from gradients of other types of chemicals. The range of possibilities is very extensive: in fact, a substantial fraction of the vertebrate genome is devoted to axon guidance messengers and their receptors.

Of course you're the expert and should feel free to disregard this or change it in any way that seems suitable to you. Best regards, William Skaggs 15:43, 25 July 2013 (UTC)

A few suggestions

Generally provides a very good coverage of the issues in axon growth and guidance, with pointers to the experimental data and theoretical models. Provides a few useful figures to illustrate key concepts.

I do not regard the following as in any way compulsory or necessary, but the article could say a little more about: (1) growth cone (axonal) branching; (2) interstitial branch formation; (3) visco-elastic constraints on axon growth and direction finding; (4) an example of how Sperry’s basic map formation idea does not match the data and new models that have been proposed (may not be able to do this succinctly).

Typos to be fixed: (1) a few Latex commands appear in the text; (2) reference required for Rho GTPases (indicated in text); (3) Topographic map formation: “the retinotectal is particularly rich” should be “the retinotectal map is particularly rich”.

All the best, --Bruce Graham 16:08, 2 August 2013 (UTC)