Do Synapses Grow From Both Sides?

Are neocortical synapses bridges that are formed by a bridging material, or are they two connection points that are drawn together (kind of like magnets)?

Does that bridging, or repositioning motion happen from both sides, or does one side do most of the work?

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Axons grow, usually directionally, meaning there is some reason they go the way they go. Dendrites, from what I understand, are more just branching out into space somewhat randomly, although some will route to other layers first? (not really sure, but in HTM this happens)

As axons and dendrites approach each other, potential synapses appear. They become more “permanent” as they are reinforced by activity across the synapse. I’m not sure whether the axon or dendrite initiates the initial connection, but I’m not sure it matters.

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I hope I’m not out-of-topic, but axonal and/or dendritic segments actively getting close to each other could also be part of the answer you’re looking for, here, I guess.

That paper explores that question

Only me inferring a rough outline from their paper :

  • IN : very actively trying to wire
  • PC axons : clueless fire&forget
  • PC dendrites : I’ll hypothesize quite active

That’s interesting, so synapses form from growth, like a plant growing toward the sun. Except, in this case, maybe the sun is also growing toward the plant.