What brain resources are needed per limb?
I have previously asked this question about the plausibility of large six-legged creatures, but I decided to split it into several more specific questions because of the advice here.
I want to first ask about the issue of how much brain (and nervous system power) it takes to control various limbs. I have rarely seen much discussion about this issue at all, except in this article, where the author notes that there are some who claim that large creatures cannot have more than four limbs because it would be too much of a challenge for a brain to handle. He quickly dismisses these objections, but I do not wish to rely on one source only, and I cannot access the reference he uses because a subscription is necessary.
The big problem is that I have tried to look in every resource I have found, and I have found barely any information about how many neurons and neuron interconnections, or how much of the brain, it takes to control a single limb. There do not seem to be any numbers or even much qualitative information I can see. Therefore, what I want to know is, for each individual limb in an average animal, how many neurons and what percentage of the brain does it take to control that limb?
If it scales by size, or there is a "law of diminishing returns" in which the more limbs are added the more it takes to control each, such information would be particularly useful to find out. Also useful would be data for creatures such as humans (because they're one of the few creatures with fine motor control of arms and hands, and I've heard that arms need more of the brain than legs do), elephants (they have a quite dextrous trunk with far more muscles in it than found in the whole human body), and insects (they're small, but they do have six legs). But really, considering the utter lack of information about this topic, any numbers on this subject would do.
Clarification
Note that I have tagged this question hard-science. I believe that in this case, the tag is appropriate as I am currently asking for information and numerical data about an aspect of real-life creatures.
This post was sourced from https://worldbuilding.stackexchange.com/q/79761. It is licensed under CC BY-SA 3.0.
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