If You Want a Nice Primer on How the Brain Works

that ranges from the whole shebang down to the level of individual neurons and cortical layering, I recommend this long post by Tim Urban, Neuralink and the Brain’s Magical Future. As the title indicates, the post is headed toward an understanding of Elon Musk's Neuralink software, and company of the same name. It's organized into these parts:

Part 1: The Human Colossus
Part 2: The Brain
Part 3: Brain-Machine Interfaces
Part 4: Neuralink’s Challenge
Part 5: The Wizard Era
Part 6: The Great Merger

Wizard's Hat from Disney's Fantasia

By all means read the whole thing. But it gets a bit wonky with part 5, which is about a whole brain interface. That's best thought of as science fiction. Here's the idea.

Magic has worked its way from industrial facilities to our homes to our hands and soon it’ll be around our heads. And then it’ll take the next natural step. The magic is heading into our brains.
It will happen by way of a “whole-brain interface,” or what I’ve been calling a wizard hat—a brain interface so complete, so smooth, so biocompatible, and so high-bandwidth that it feels as much a part of you as your cortex and limbic system. A whole-brain interface would give your brain the ability to communicate wirelessly with the cloud, with computers, and with the brains of anyone with a similar interface in their head. This flow of information between your brain and the outside world would be so effortless, it would feel similar to the thinking that goes on in your head today. And though we’ve used the term brain-machine interface so far, I kind of think of a BMI as a specific brain interface to be used for a specific purpose, and the term doesn’t quite capture the everything-of-everything concept of the whole-brain interface. So I’ll call that a wizard hat instead.

Um, err, no. Color me skeptical, very skeptical.

This post captures my skepticism: Why we'll never be able to build technology for Direct Brain-to-Brain Communication. Of course, there's been quite a bit of work on coupling with the brain, and I've got a hand full of posts on the subject.