Corollary discharges, on one level, resolve many questions about behavior, but on another level, pose many questions as well. Corollary discharges provide a very interesting explanation about astronaut flight sickness, jet lag, and motion sickness, as discussed in class. The introduction of CDs helps to make more order in our structure of the nervous system, such that behavior may be considered to be interactions of central processing generators, with CDs as communicators between CPGs. For example, in the poking eye experiment, a CD sends a signal to the brain from the eye to tell you that the image is not really moving (when one closes 1 eye and waves one finger around and follows finger movement with eyeball, activating a CPG, images other than finger appear stationary).

CDs appear slightly mysterious to me. I don't know exactly what constitutes these 'signals', except that they are action potentials in axons, just like everything else, but they seem to be a big part in understanding our nervous system, with a certain job which does make them different from ordinary action potentials. We haven't really described the signals, nor their mechanism, nor have we tried to quantify them. We've gone from the quantity, 10^12 neurons, to something quite intangible, something that has multiple linkages and multiple effects. The statement in class, "your perception of the world is colored by CDs," suggests to me the idea that perhaps you can control mind over matter in some situations, as we try to do when we fly across time zones and turn off the lights in the plane and try to change the body's internal clock to alleviate jet lag.

Yes, there is some abstractness in the CD notion, but that shouldn't be mysterious. There is nothing special about the neurons or action potentials involved, only something special about the interconnections, and the fact that because of them the neurons carry information about the current state of particular parts of the nervous system rather than information about external inputs. That ok? PG