textbook on the human brain for computer scientists/machine learning professionals?
There is no "textbook" on this. However, there is a book! It is How to Create a Mind by Raymond Kurzweil, the director of engineering at Google. Excellent book that explains the brain from a computer-science perspective. It goes into a lot of detail.

Check out the intro sound bytes on Audible.

For a closer to the metal (i.e. actual implementations of models of the brain), check out Cognitive Architectures, such as ACT-R, Soar, CLARION, ICARUS, EPIC, LIDA, etc. Here is a survey.