This is a cool metaphor I thought up a while ago. It relates how the Human CNS is organized somewhat like an Operating System. (Namely, a Unix type OS.) I actually started it mostly as an experiment in how far I could carry out a metaphor, but it is nifty nonetheless.
Before starting this, you may want to read Triune Brain Theory.
The basis of my metaphor is layering, in that both Operating Systems and the human nervous system have different layers, where they both abstract and compute data, leading to input becoming both more complicated and more simple.
The first layer of both the nervous system and an OS is the hardware, that is the periphreal nerves in a human and the physical layer of a computer. This would also include the hardwired data control parts of both humans and computers, such as a SCSI card or the medulla oblongata. This layer of both computers and people is incabable of autonomous action, although in humans it can adapt and have reflexive action.
The second layer in the cns and an os is the diencephalon and kernel. This level serves as a hard ware abstraction layer, where all of the little details aabout how the physical stuff works is abstracted, and all the signals coming in from input devices and sensory neurons are routed and sent to the right place. In the human brain, this is called the diencephalon, consisting of the the thalamus and the hypothalamus. In the computer, this is the kernel. And as is often the case, both in the human brain and in a computer, these parts are smaller then the processes they control.
The third layer is the shell, or limbic system. These areas are responsible for storing environment variables. It is actually quite possible, and quite common, for user applications and conscious thought processes to run without using this layer, but most of the time it is very helpful to have it. For example, when driving in a city that has its streets in a grid pattern, it is not neccesary to consciously remember the way back from where you started, or to logically work back your course. Instead, a part of the human limbic system automatically keeps track of spatial information. I would say that in general, the amount of environmental variables kept track of by the limbic system is proportionally much greater than what is kept track of by an OS shell. Also, as someone once pointed out to me on Slashdot, shells are really just a different type of application. And, indeed, in the CNS, certain parts of the limbic system, such as the cingulate gyrus, are structurally similiar to cerebral cortext, but other parts, such as the amydgala, are anatomically different.
The final layer, and the layer that all this stuff was built for, is the layer of conscious thought processes, or user applications. All of this complicated organization underneath this layer, means that I can think things, or use a computer, without having to think about how it all works. Just as my computer's kernel transfers data from this application using TCP\IP over specific hardware that it has drivers to, to the everything2.com computer when I click idea, so when I want to go get a glass of water, I don't have to consciously think about how to balance, what thirst is, or whether I exist. These environmental variables and hardware processes are taken care of by my thalamus and limbic system, leaving my cerebral cortext\conscious thought process to think about other things, such as why it doesn't have to think about these things.
So there is my attempt at making a cool analogy. I hope you enjoyed it.