As Jeff Hawkins writes in "On Intelligence":
When I first became interested in brains many years ago, I went to my local library to look for a good book that would explain how brains worked. As a teenager I had become accustomed to being able to find well-written books that explained almost any topic of interest. There were books on relativity theory, black holes, magic, and mathematics— whatever I was fascinated with at the moment. Yet my search for a satisfying brain book turned up empty. I came to realize that no one had any idea how the brain actually worked. There weren't even any bad or unproven theories; there simply were none. This was unusual. For example, at that time no one knew how the dinosaurs had died, but there were plenty of theories, all of which you could read about. There was nothing like this for brains. At first I had trouble believing it. It bothered me that we didn't know how this critical organ worked. While studying what we did know about brains, I came to believe that there must be a straightforward explanation. The brain wasn't magic, and it didn't seem to me that the answers would even be that complex. The mathematician Paul Erdös believed that the simplest mathematical proofs already exist in some ethereal book and a mathematician's job was to find them, to "read the book." In the same way, I felt that the explanation of intelligence was "out there." I could taste it. I wanted to read the book
There is more literature about the brain nowadays. However, on when it comes to the theory side of things, not so much. On Intelligence is a great book (official site, wiki, pdf). But they are some missing pieces in my opinion, mainly about higher-level processes such as language (and maybe consciousness).
Are there any references or books about the human brain theories or models? I am interested for plausible ways it could work in engineering and mechanic terms, not about how the brain implements this specific model.
Some other material that I find relevant is the work of Josh Tenenbaum, especially this lecture: How to Grow a Mind: Statistics, Structure and Abstraction. (other lectures)