In humans, around a million axons [1]. But not every lesion severs all axons. It's very challenging to stimulate individual axons as well, especially at scale.

In humans, around a million axons [1]. But not every lesion severs all axons. It's very challenging to stimulate individual axons as well, especially at scale. https://www.frontiersin.org/articles/10.3389/fnana.2017.00129/full https://www.frontiersin.org/articles/10.3389/fnana.2017.0012...