One of the many impressive abilities of the human mind is its ability to focus. A mind can focus on a particular topic or a particular problem, restricting itself so that it only thinks about that topic. A mind can also focus on some particular time when something occurred. For example, you may think for a few minutes only about some day that was the happiest day of your life. Or you may think for a few minutes about some bad experience. Or you may spend a few minutes thinking about a restricted subject, such as the death of John Kennedy.
If the brain is the source of the human mind, then we should be able to find in the brain some physical effect that is similar to the mind's ability to focus on a particular topic. It is easy to imagine some extraterrestrial creature that has a thinking organ that shows clear signs of focusing. We could, for example, imagine such a creature having a brain with a movable read-write unit that moves around from one part of the brain to another, like a subway car moving from one subway station to another. If this moving read-write unit moved to one particular hundredth or thousandth of the brain, and scanned information from that tiny part, that would be a physical reality that might correspond to a mind focusing on one particular topic or one particular time in a person's lifetime.
Nothing like such a moving read-write unit exists in the human brain. There is no anatomical structure that moves around from one part of the brain to another. The brain has nothing like a read-write unit.
There are no anatomical parts in the brain that move around on small time scales. No cell or structure moves from one part of the brain to another over a time scale of a few minutes. The neurons and synapses of the brain are structurally entangled in a way that prevents any short-term movement by them. Just as a tree is connected to many roots that lock it into place at a particular spot, neurons have many synaptic connections that lock the neurons into place at a particular spot in the brain.
Searching for the topic of "moving parts in the brain" you will get a discussion of movement during morphogenesis or human development. That is a very slow process occurring over weeks or months, something that is useless in trying to explain how a brain could explain the mind's ability to focus. Searching for the same topic will give you some sites discussing what are called microglial cells. Such cells have a function of helping the brain deal with injury or infection. A paper "The Physiology of Microglia" tells us that such cells move at a speed of up to seven nanometers per minute (a nanometer is a billionth of a meter). Such a speed is very many times too slow to support any idea that some movement of microglial cells might help explain a focusing effect in the brain.
Could there be any focusing effect caused by extra blood rushing to some part of the brain? Scientists do not claim that nerve signals are transmitted by blood. Nerve signals are transmitted electrically and chemically by things such as neurotransmitters that must travel across the gaps of synapses, a strong slowing factor. There is no reason to believe that some increased blood flow to some particular part of the brain could cause some kind of mental focusing effect.
Scientists have a device to measure blood flow in the brain: the fMRI machine. Neuroscientists have given us decades of misleading statements and visuals relating to this device. The fMRI machine is commonly depicted as a device for showing the level of brain activity. It is instead merely a measure of blood flow in the brain. For decades neuroscientists have been guilty of publishing deceptive visuals based on fMRI machine scans. In such visuals very tiny changes in blood flow such as 1 part in 200 are depicted with very different colors, thereby creating the impression that there was some big difference, when there was really only a tiny difference such as 1 part in 200. The misrepresentations that go on in brain imaging studies are discussed in my post here, entitled "Neuroscientists Keep Using Misleading Coloring in Brain Visuals."
Let's look at some things that can focus:
- Eyes are able to focus, because eyes have muscles that change the shape of parts of the eye when someone focuses on an object he is looking at. There are no muscles in the brain, and nothing similar to eye focus can occur in the brain.
- A book also has a built-in mechanism allowing a kind of focus to occur. The pages of the book and the binding of the book allow the book to be opened to a group of two pages. That is a kind of focus. There is no corresponding mechanism in the brain. A book can be opened to two particular pages in it, temporarily restricting reading to those two pages. A brain cannot ever have some kind of modification so that it becomes temporarily restricted to reading from one particular part of the brain.
- A microscope has circular controls that can be moved to allow the microscope to focus on one tiny area in front of it. There is no comparable physical mechanism in the brain.
- A 35 millimeter camera has circular parts that you can use to focus the camera on one area or spot in front of it. There is no comparable physical mechanism in the brain.
- A telescope has one or more circular controls that can be moved to allow it to focus on a particular part of the sky. There is no comparable physical mechanism in the brain.
- A film projector and a roll of film have a physical structure that allow focus on one particular frame on the roll of film at any particular instant. There is no comparable physical mechanism in the brain.
All six of these things have one thing in common: they all have non-microscopic (i.e. macroscopic) moving parts that allow the focus mechanism to occur. There are no non-microscopic moving parts in the brain. So there is no neural account which can explain how a brain could achieve some focus effect that would correspond to the mind's ability to instantly focus on any of countless thousands of different topics. The lack of any physical focusing mechanism in the brain corresponding to the mind's ability to instantly focus on some topic is another reason for disbelieving that brains are the source of the human mind.
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