Every so often, I run across a study that elegantly elucidates a solution to a problem I failed to think of, but which in retrospect appears to be a very serious problem I really ought to have wondered about. When this happens, it is both exciting (I am learning something really neat, after all) and disheartening (why didn't I even wonder about that?) at the same time. A recent study pointed out and summarized by Neuroskeptic resulted in such an experience for me.
Since Neuroskeptic has already summarized the study quite nicely and readably, I will only briefly explain what was going on here to convince you it is worth following the link. Basically, the problem that I failed to wonder about was how branching neuronal processes managed to avoid entangling themselves and mainly forming self-connections. I had wondered about the problems of axonal guidance, particularly in relation to long distance connections, but I also should have wondered about the lack of tangling in the dendritic trees and local axonal processes as well. I also knew chemical markers would be involved, as previous evidence for chemical markers guiding axon growth has been found. However, somehow developing a unique chemical marker for each neuron to keep it from entangling itself seems like something that would be rather difficult to do. Fascinatingly, though, researchers from the Department of Biological Chemistry at the Howard Hughes Medical Institute and the David Geffen School of Medicine at UCLA have found evidence for a remarkably elegant solution. I highly recommend reading Neuroskeptic's summary and checking out the paper itself.