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 I thought our discussion last week about CPGs and corollary discharge signals was really intriguing. Mostly I found it interesting that we have an innate ability walk, eat, and keep ourselves afloat in water and that the period described as “learning to walk” is just a necessary delay for maturity. That fact that these motor patterns are built-in and allow us to do things that we may not have learned how to do is amazing and is a further testament to the sophisticated inner workings of the human body. If we are born with CPGs for specific motor patterns, does this extend beyond movement? For instance, are we born with CPGs for thinking?

From CPGs we moved to corollary discharge signals, which coordinate the CPGs and go back across the NS to the sensory side and influence how input signals are interpreted. What I found most exciting about our discussion is that our experience of the world is a function of what we are doing combined with our own state. This means it is impossible to treat any two people the same because their experiences are so different. Motion sickness is a great example of this phenomenon, as it is a mismatch between expectations of input and actual input. I have not experienced extreme cases of motion sickness, although as I have gotten older I have noticed that my predisposition for it has increased. I used to be able to read for hours in the car, watch movies, etc; but now I can only read for a short amount of time before I start to feel sick. It now makes sense to me that this is the result of the discrepancy between the expectations of my NS and what is actually occurring. The corollary discharge signals say I am not moving because I am sitting in a car. However, visual input signals convey objects (trees, other cars, buildings) streaming by the window. Therefore, my sensory input does not match my NS. If the input difference is small, the NS can easily adjust. But if the difference is large, the NS says something is terribly wrong and it has difficulty adjusting. It is puzzling that over time I have become more prone to motion sickness and I wonder what the reason for this is.

In this discussion of corollary discharge signals, we mentioned that the experience of pain can be likened to motion sickness. If I assume there are similar mechanisms involved in the sensation of pain as in motion sickness, then it must follow that the NS and the input signals do not agree and the result is pain. This seems to be a more confusing notion to explain, as I am not sure where to begin. Does the NS expect there to be a lot of sensation changes due to harm to the body, and then the input signals are different? Or is it the other way around? Do the input signals exceed the expectations of the NS? I have had quite a few injuries, due to athletics, and most have been fairly painful. It would be interesting to understand what goes on behind the scenes and what causes such a wide range of intensities of pain.