the Neural part of the word could be taken two ways.
One being actually in the brain, the second being metaphorical. Like the World Wide Web is like a spider's web, with lines linking up all over the Earth to provide us this connection, the Neural Net indicating that it is much more complicated, being over an entire sector of systems with hundreds of planets rather than just the one.
I like to think it's a little bit of both. I've always seen it as something that's implanted into your brain, but I've also RPed it that you can access your neural net via logging into a terminal.