[fnl]

I would honestly say we really have no clue, and maybe add that as far as we can tell, activations play as much of a role in intelligence as a myriad of other factors.

But more generally, I am just so tied of this "brain metaphor" on deep learning. It is a funny way to wake up your students (well, at least 10 years ago it was...), but trying to stretch this metaphor much more than that is just painful. Heck, even the activating "functions" (plural, as we now know) in a neutron isn't really a set (!) of (singular, independent) functions, it's just a top level name for a mind-boggling number of things happening as neurons "fire", with a mathematical formalism to approximate what's going on. In fact, calling an activation a "function" is probably belittling the biological processes behind them.