This is the 25th anniversary edition. The book first came out in 1992. The purpose of the book is to describe the brain in terms of networks, specifically networks of neurons, building on artificial neural network research in the previous years. The book discusses how we can read across from one to the other. Whilst considerable further work has since taken place in both neuroscience and machine learning, the book remains fresh. It also contains a particular good discussion of what a computer is and the parallels and differences between a brain and the hardware sitting on our desks.
Link to book: https://www.amazon.co.uk/Computational-Brain-Neuroscience/dp/0262533391/ref=sr_1_fkmr0_1?s=books&ie=UTF8&qid=1496058460&sr=1-1-kmr0&keywords=the+computational+brain+by+patricia+churchland+and+terence+sejnowski