Agree completely. The brain is so incredibly complex that we've barely scratched the surface. It's not just neurons, which are very complex and vary wildly in genetics between them - it's hundreds of other helper cells all interacting with each other in sometimes bizarre ways.

To try to boil down it all to any simple signal is just never going to work. If we want to map consciousness it's going to be as complex as simulating it ourselves, creating something as dense and detailed as a real brain.