Review for NeurIPS paper: Attention-Gated Brain Propagation: How the brain can implement reward-based error backpropagation

Additional Feedback: - To me, the fact that learning was not much slower than standard supervised learning seems like the most important result of the paper, and I would have liked to see more analysis of how this works (rather than just a report of the empirical result). Additionally it would be nice to see a more systematic exploration of how this scales with the number of classes, including greater numbers of classes. This is an important and strong statement about physiology, but I'm not sure the references support it. Many references are given, but this isn't the main topic of any of them. I looked fairly carefully for support for this statement in the first reference and didn't find it.