In a sense, we're already able to "hook our brains up" to computers to increase our intelligence -- or, at least, our productivity. We're not using neural links or implanting machines in our crania, but we use our eyes and fingers to interact with computers and expand our mental capacity every single day.
Sociologists have long studied the phenomenon by which modern people off-load their memories (phone numbers, email addresses, sports trivia, etc.) to electronic devices. As these devices become increasingly interconnected and achieve larger capacities, it's inevitable that people will become more and more strongly dependent upon them for even basic tasks like contacting their families or knowing how to get to the airport.
- Warren