Perspicuo
Veteran Member
Why does the left side control the right side? Why the decussation of the pyramids?
The mystery pops up once in a while on da webs, and several people have offered different explanations, such as the change from having the spinal cord on the ventral side to one on the dorsal side. That doesn't say much and doesn't seem satisfying. But this next one is much more compelling my view: http://sol.rutgers.edu/~shinbrot/NewHome2006/Papers/Decussation11.pdf
Mathematics to the rescue.
The mystery pops up once in a while on da webs, and several people have offered different explanations, such as the change from having the spinal cord on the ventral side to one on the dorsal side. That doesn't say much and doesn't seem satisfying. But this next one is much more compelling my view: http://sol.rutgers.edu/~shinbrot/NewHome2006/Papers/Decussation11.pdf
Many vertebrate motor and sensory systems “decussate” or cross the midline to the opposite side of the body. The successful crossing of millions of axons during development requires a complex of tightly controlled regulatory processes. Since these processes have evolved in many distinct systems and organisms, it seems reasonable to presume that decussation confers a significant functional advantage –yet if this is so, the nature of this advantage is not understood. In this article, we examine constraints imposed by topology on the ways that a three dimensional process or and environment can be wired together in a continuous, somatotopic, way. We show that as the number of wiring connections grows, decussated arrangements become overwhelmingly more robust against wiring errors than seemingly simpler same-sided wiring schemes.
Mathematics to the rescue.