in a dark alley may cause you to flinch next time you enter one. Another thing that concerns wiring and rewiring is the neurological phenomenon of synesthesia. There are over 60 known types of synesthesia. An example would be a synesthesiat hearing a sound and colors flooding their vision or someone reading a passage of words and each letter evokes a different color or a different smell or a different taste. Certain sounds cause the person to feel certain things in turn, or see spots of color dance across their vision. Neurologists agree that this occurs of faulty wiring in the brain, that "neuron circuits that process a sense accidentally strum circuits of another sense, causing both to go off simultaneously". It is debated how this happens. As a child, one possesses more neurons than necessary and the unnecessary ones are pruned away and die when not used. Some believe that synesthesia is a result of poor pruning. Albert Hoffman helped scientists further understand synesthesia by creating a certain psychedelic drug known as LSD. Created in his lab, he tried it, and was startled by the results. It ultimately showed that we all carry the latent ability of synesthesia if we knew how to tap it as LSD does. Cajal (from the previous chapter) pointed out that adult neurons and neuron circuits could not renew themselves, and once they were dead, they were dead for good. He said that only children could renew their brain tissue. This is true to some extent, though for adults, while they cannot regrow neurons, they can rewire circuits in their brains with hard work. Chapter 4: Facing Brain Damage This chapter starts with the introduction of mutilés, men who had various parts of their faces blown off by the metal weapons used in the Great War. Their defaced faces, faces without noses or eyes or cheeks, were the root of much sadness and insecurity for the men, and many committed suicide. An American sculptor Anna Coleman Ladd traveled and set up a business for these men, and she would create faces for them out of plaster and ceramic and paint, making them startlingly realistic. These faces made the men happy and helped them assimilate back into society. Despite this, the faces could not smile or kiss or chew and the paint soon chipped. Related, a Japanese scientist Tatsuji Inouye examines soldiers who had been