One of the most interesting parts of this course for me was actually not something that we directly covered, nor something that we even discussed very often, yet it is one of the most crucial parts of all the sensory systems that we have been learnig about: efficiency. We’ve spent this term talking and reading about the intricacies of the central nervous system, and how vital its use is to our everyday lives. From a rabbit seeing a predator approaching, to a baseball player hitting a pitch, we perceive things at an astonishing speed, and with incredible accuracy. This is what I think made this course so interesting: learning about how complex our brain is and how it allows us to see, feel, smell, taste and touch, while keeping in perspective that all of the information is obtained, processed, and interpreted in a fraction of a second. Seeing is one of the best examples of this, and in my opinion is the most fascinating of all the senses (and the one that I have already said I would least like to loose: see blog entry “hearing vs. vision: the showdown”). Imagine you are the third baseman for the Boston Red Sox. The pitcher hangs a curveball, and a hitter hits a hard linedrive down the third base line. From the moment the pitcher releases the ball, to when the batter makes contact, to when you make Sportscenter’s top playes with a diving catch, is less than a second. Consider now what this third baseman needs to see in order to make the play. First, he needs to see the pitch. Assuming that the baseball is travelling 90 miles per hour, that means that from when the pitch is released to when it reaches the hitters bat, about 0.46 seconds have gone by. In this time, light must reach the retina, be absorbed by photoreceptors, get through the horizontal, amacrine, and bipolar cells, have an action potential from the retinal ganglion cells travel along the optic nerve to the LGN, where motion is picked up, then the LGN must transmit information to the V1 area for local motion detection using direction sensitive cells, then information must be passed to the MT area where the motion of the ball is further analyzed, and finally the information from all of these calls and areas must be processed in the MST area, where not only the ball is registered, but the pitcher’s bosy position, the runner on first breaking to steal second, and the batter taking swings in the on deck circle. And this all takes place in less than one half of a second. The situation becomes even more complicated once the batter hits the ball. According to Jonathan Drobnis (http://ffden-2.phys.uaf.edu/211_fall2002.web.dir/Jon_Drobnis/bmb.html), if a player swings his bat 70 mph and connects with a ball going 90mph, the resulting speed, is close to 160mph. For the third baseman, this mean that he has less than 0.4 seconds until the ball reaches him, and there’s still a lot to be done to make the play. First, the ball must be seen. All of the connections just described would have to occur, as well as all of the necessary analysis of information, and the command impulses that would have to be sent to muscles in order for him to dive to his right, stretch his arm out, and close his glove around the ball, and remember, all of these commands, from pitch to catch, are occuring in less than 0.9 seconds.
Seeing is just the example I chose to use to show how efficient and accurate our sensory systems are. Touch hearing smell or taste are all extremely efficient, and would all provide excellent examples of the speed with which we process the events in our lives. If we were not able to perform these functions as fast as we do, or if our brain did not evolve in exactly the way it has, our lives would be drastically different from the way they are now. There are simply too many examples of how impressively fast our processing centers receive and interpret information, but I hope the one I used is a good one to give an idea of how fast everything that we have been learning about this semester happens. This blog entry was supposed to be about the most fascinating this we learned this semester, and I wrote about something we rarely, if ever, discussed. Why? Because evev if it was never explicitely stated, and no matter how long it took us to learn the pathways required for pain sensation, or color perception, the actual events that we were discussing happen every moment of the day, and happen faster than I can really appreciate or understand.
April 27, 2008
