I sat down to write this essay with, what I thought was a pretty thorough understanding of class on Thursday, but it turns out, I have myself confused. Originally, I looked at CPG's and the motor symphony as opposing views. I knew that behavior wasn't an "either/ or" situation (meaning that behavior is not result of one or the other), but rather a combination of the two. I had thought,though, that the main ideas of each were considerably different. I was confident that when I began my essay, I could write about how the two work together to produce the behaviors we see everyday. BUT when I flipped through my notes from class, I reorganized my ideas. Now, I think that motor symphonies are simply an extension of the CPG idea. Now I may be wrong about this (hence, my confusion), but if CPG's are generations of output even in the absence of input and a motor symphony says that any output is an enormously intricate coordination of motor nerves, then OF COURSE the two work together. This just means that a motor symphony can occur without an input. We know that CPG's exist from the earthworm experiment that demonstrated movement without nervous system connections, as long as the skin is re-stitched. This supports the idea that there are pre-written scores that are housed in the nervous system which can occur regardless of the input and can also occur without connections throughout the entire nerovus system.

The notion of pre-written scores is what strikes me as more interesting than the motor symphony and the CPG's. If we do indeed have such pre-determined (possibly learned, possibly genetically determined) templates for movement and behavior, how many do we have? If these movements and behaviors are independent of brain influences and sensory input, what provokes them and what, if anything, has control over them? I am sure that these pre-written scores are limited to very basic movements, but it is eery to think that our bodies can carry out functions such as walking or moving our hand without our brain's control--these can just "happen". This makes me think back to the article I read on Phantom Limbs.....maybe the patients who feel phantom limb movement are simply experiencing the nerves attempting to carry out these scores of movement that had been determined before the limb had been lost. The detailed network of nerves that are involved in a motor symphony are obviously used for CPG's and for responses to input. The symphonies are involved in every type of movement because no output requires just one nerve-there has to be a series of communications from nerve to nerve to nerve....from sensory to interneuron to synapses to more synapses to more interneurons to the brain to other motoneurons, etc. This idea supports how I have looked at behavior all along. The CPGs and pre written scores, however, have made me reconsider behavior as more than reactions to input. I always accepted the autonomous functions of the nervous system, but I always thought that the brain still had some sort of control over this autonomy. Now, with this pre-determination factor, maybe the brain isn't as in control of EVERYTHING as I had once believed.

Interesting thoughts. Yes, YOU probably have less control than you once believed, and that is important to understand. Don't, though, automatically equate "you" with the "brain". There are CPG's in the brain, as well as in the spinal cord. The distinction is really between "I-function related" (a PART of the brain), and non "I-function" related. Are you less confused now about "motor symphonies" and CPG's? The former is simply a fancy way of saying movement corresponds to complex spatio-temporal discharge patterns in motoneurons. The latter is (one) explanation of how those patterns are brought about, another possibility being through the use of sensory input. PG