Well, I think it may not just be Hebbian learning but likely Balanced Amplification learning [1] as well which propagates quite a bit faster. Promising paper came out recently echoing this phenomena globally with a model of visual perception in the macaque brain[2].

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2667957/ [2] https://www.cell.com/neuron/fulltext/S0896-6273(18)30152-1?