So now that I got way off track...I guess its time to write about the topic of the week - audition, otherwise known as hearing. This turned out to be just as complicated as vision once all the information is sent to to the brain. There are tons of different pathways that the informaton can follow but the book only talks about a few, nor does it give much information about the processing that goes on in the cerebral cortex, although it does talk about tonotopy, which is similar to retinotopy in the visual system. I also learned about the ossicles, or three little bones in the ear. I was always curious as to what they were there for and now I know that they amplify sound waves from the tympanic membrance to the cochlea. I learned quite a few other things about hearing and the transduction of sound waves but I don't think it necessary to repeat them all.
I was surprised that there was no mention of sound and memory or sound and emotion in the text. It seems to me that there must be a connection as music is used to evoke certain feelings in movies and listening to music can bring back memories and emotions. Are we programmed to feel emotions when certain sounds or tones are presented or are our reactions to music based on previous learning? I'm curious about this as I've found, as I'm sure most people who listen to music have, that the music I listen to often depends on how I'm feeling or that music can change how I'm feeling. I've also read that music (I think from the Baroque period) increases creativity, and for this class in the Sacks book about the patient Rebecca whose body movements, like other retardates, became fluid and graceful in the presence of music. Somehow sound, which in its simplest form can be described as variations in air pressure, can effect our limbic system and motor system.
I'm also curious as to why some people are bothered by sounds that others are not. Why do some people need complete silence to fall asleep and others can fall asleep in the presence of many sounds? Similarly, how is it that some people can sleep through thunderstorms and police sirens while others wake up at the creak of a floorboard? This must somehow involve the reticular activating system. If this is correct, it would then seem that people who do not wake up during loud noises are poorly adapted to live in the wild, as they would sleep through an animal creeping up on them while those who do wake up would be more likely to escape and survive a possible attack. This idea can also be transferred to vision. In prehistoric times those of us with poor vision would be less likely to survive than our counterparts with perfect or almost perfect vision. So it seems that in the evolution of modern man, as we moved out of the wild, characteristics such as poor vision and a poor reticular activating system which were undesirable and could possibly result in the shortening of one's life, became less important in the overall survival process.