Please 'waste' 23 minutes and watch this video. It's fascinating (and, you'll have plenty to say in your TOK class...)
Quoting from TED:
V.S. Ramachandran is a mesmerizing speaker, able to concretely and simply describe the most complicated inner workings of the brain. His investigations into phantom limb pain, synesthesia and other brain disorders allow him to explore (and begin to answer) the most basic philosophical questions about the nature of self and human consciousness.