The Man Who Mistook His Wife for a Hat by Oliver Sacks. Summit Books, Simon & Schuster, Inc., 1985. ISBN 0-671-55471-9.
A good, weird, non-fiction book about neurology. This is Oliver Sacks' best known work, and for good reason.
The title describes an actual case. A man came to consult with Dr. Sacks because he seemed to be confusing people and objects. The man did not feel that it was a problem, but his friends and wife had convinced him otherwise. It turned out that while his vision was fine he had damage to his right hemisphere that prevented him from processing this information correctly. He had no problems with abstract forms, and could describe objects in great detail, but couldn't make the connection of the description with the function of an item with anything more than vague approximations. He could not distinguish his foot from a shoe, or his wife's head from his hat.
This is only one of many cases found in the book, many of them odder. It's worth reading just so you can hear about The Weirdness That Is Humanity. But even better, many of the losses and gains of his patients are things we have, but are not aware of. Knowledge we don't develop, and senses we don't realize we have. You may hear a lot about this book in philosophy classes, as it points out the holes in our knowledge of epistemology and questions our brain's ability to form an objective view of reality.
There are cases of people losing all sight, being completely blind, failing to even recognize the meaning of the words 'seeing' and 'light' -- and not realizing that they had lost any capacity. A part of the world lost, with no feeling of loss. People who failed to recognize that a limb was connected to their body -- despite the fact that they had had their leg since they were a baby, and it was firmly attached to their body. It was simply undeniable to them that this limb was an alien object. There are also cases of savants, people with odd types of memory loss, and who have visions, and many other quirks.
This book isn't particularly technical, although it is sometimes rather dry. The author sometime goes off into philosophical rambling on 'what it means to be human' or some such. But it is well worth reading, and not boring once you actually get into it. It's also sliced into bite-sized pieces, so if you decide you don't like the first couple of cases, you can just quit. You have nothing to lose. Your local library has a copy -- give it a try. Neurology is more interesting than you think.