Small axons are lost quickly

[jordansparks]

I've been made aware of another form of degradation that happens quickly. Dr. Andrew McKenzie posted on Substack in May:
https://neurobiology.substack.com/
He pointed out that in the paper by Helmstaedter, it was mentioned that some axons are ten times smaller than dendrites in the grey matter and they easily get severed, making it impossible to trace them. Well, that's bad.

He then mentions another study, down in his section 5, that talks about how neurites recognize self when they are making connections. Each neuron apparently has a unique set of protocadherins so that it won't accidentally make a connection to itself. That's really cool. It also means that the severed axon issue is a lot less important than it might initially seem. Future technology has a way to match up the two broken ends of the axon to allow accurate tracing. It should also finally allow tracing of a neuron across an entire brain, something that is statistically impossible with current technology because of the way small errors accumulate over those distances.