By now I've read a lot of articles — some pop and some tech and some speculative — about how the brain works. There are some basic premises.
1 Everything is an accumulation that builds on and emerges from what was already there. Very few parts are discarded, though they may be modified or even transformed into doing something quite different. The brain works as a whole, interacting rather than isolating.
2. The brain is the operating system for the intake and output of the body. Without a body, there is no brain. Believing that a brain floating in a jar or a computer intelligence program is the equivalent to a brain is a rookie mistake, in literary terms, substituting a part for the whole.
3. A brain is basically an organization of single cells that communicate with each other two ways: through filaments (axons and dendrites) that “wire” cells together and solutions that alter the whole environment, which is fluid (excretions and secretions).
4. Over time, some neurons have become specialized one-by-one, so that they have extreme sensitivities necessary for operating. Examples are knowing which way is “north” (probably a magnetic detection); sensing where walls and precipices are; “feeling with” other humans (empathy); and probably more (some estimate hundreds).
5. Specialized neurons may form into concentrations, small organs anatomically separable, that intercept and process neuron transactions. They may become specialized between one end and the other. We think sensation-records may go in one end of the hippocampus, be sorted by significance and attached to pre-existing records which means they are more permanent, and then be discarded if unimportant.
6. The brain does as much suppressing and discarding as using and preserving. It tends to save what resembles previous records. There is an idea that at night during sleep, the neurons contract so that there are wider spaces among them and the brain fluid washes through the interstices, removing debris (stray molecules or bits?) which is why we can think better in the early morning.
7. The filaments that hook up systems of impulse code respond to how often they are traveled and get stronger if they are used a lot. In time, they form “hubs” (there are hubs associated with each major sense intake organ like ears and eyes) and eventually there is so much traffic to keep organized that a “platform” is needed to sort them and decide which ones demand action. There are some intakes that are so dangerous (the sight of snakes or tigers) that they bypass the platform and go straight to action.
8. The “cortex” of the brain is a thin sheet, or rather several thin sheets on top of each other that wrap the whole brain. One of them is imprinted by neural action with a distorted map of the whole body: distorted because there are many neurons devoted to some parts and few that record others.
9. The brain is constrained by the bone box, the cranium, in which it develops, but in some circumstances and over millennia even that bone can be pushed out to make more room, and this is how humans got foreheads. Behind that bulge is the pre-frontal cortex, a part of the cortex that contains what makes humans different from all the other animals. It houses the humanities, including the sciences and other pattern-developing. This is the part that used to be separated by cutting, inserting a scalpel through the eye-hole of the skull. It made the person much more manageable because now they were domestic animals, pre-humans.
10. Much of what we know about the brain comes from such actions. We send electrical impulses through the brain as a whole; or cut away the skull to test individual locations, even to burn them away; we send magnetic impulses across from one temple to the other; we use MRI and other machines to record the impulses rushing around through the neuron filaments and also the volume of the blood flow; we x-ray; we take samples of brain fluid by removing it from the spinal column, which is continuous.
11. A major surgical intervention is separating the two halves of the brain. In some circumstances, one-half can operate as a whole brain. In other cases, the two sides — which normally exchange info through the corpus callosum, which is a major bundle of neuron filaments — will specialize. When specializing the sides will create new hubs for new skills which may seem like one thing, but are often combinations of sub-skills, like the ability to recognize shapes + the ability to associate shapes with spoken sounds + the ability to organize sounds into words with meaning + the ability to use words in abstract ways to follow patterns of thought. These are cumulative, so that a person who cannot form words cannot discuss abstract ideas in words. But they CAN still use the metaphorical sensory images to form abstract ideas. People who can do this, which is likely to co-exist with word skills, are called “artists.”
12. The activities of the sensory neurons and their filaments (called the “connectome”) interact with the molecular messages floating in the blood, the lymph, and engulfing any organs with receptors. They may cause organs to do something, just as they affect muscles, though the latter are usually controlled by the filament nerves. Organs responding to the molecules of the blood are often felt as emotions. (Heart beat, stomach contractions) And moods.
13. Because the floating messages and the sensory equipment of the body can with their coding summon up images and memories of emotions, humans react to words, movements, light, skin perceptions, sounds, tastes, and so on. These can be so strong that it is as though they were actually happening. People vary greatly in their ability to receive and their ability to produce all this. Cultures affect which will be valued and trained in their children and this will determine much of what their world is like, because individual understanding of the world “outside” the human is always much more limited and interpreted than what is kept inside.
14. Molecules that enter the human body through eating or breathing or penetrating the skin can alter these functions in subtle ways, possibly detectable by the individual (getting drunk) or possibly not (developing diabetes). Part of evolution is that some people will handle this better than others. We’d better hope that we have outlier people who can survive our plastics and solvents, let alone radiations.
BRAIN FUNCTION IS A WHOLE BODY AND WHOLE CULTURE ENTERPRISE. IT IS THE PROCESS THAT CONNECTS US TO THE COSMOS.