When neuroscientists attempt to describe electrochemical effects moving around in the brain, they describe it in terms of what is called an action potential. An action potential is an electrical change in a neuron which can be transmitted to other nearby neurons. Now, there is a related question very relevant to the issue of whether the brain can actually be the storage place of human memory or the source of human thought. This question is: can these action potentials make up reliable memory signals or thought signals that travel around in the brain? For example:
- Could a brain retrieve some memory information stored in one part of a brain, and send that information reliably (as a kind of coherent signal) from one part of the brain to another part of the brain (perhaps from one part storing the information to another part more involved in attention or current thought)?
- Could a brain send some information arising from thinking from one part of a brain to another part (something that would presumably be necessary for a brain to have complex thoughts combining simpler ideas)?
In previous posts on this site I have discussed a major reason for thinking that the answer to the first question must be: no. The reason is that information does not reliably transfer across the synapses that separate neurons. It has been established that action potentials only travel across synapses with a likelihood of about 50% or less (some estimates are as low as 10% or 20%). So if the brain tried to retrieve detailed information (such as a sentence of text) from one part of the brain to another, and each synapse transmitted an action potential with a likelihood of less than 50%, than the information would not be reliably transmitted.
A 2020 paper states this:
"Neurons communicate primarily through chemical synapses, and that communication is critical for proper brain function. However, chemical synaptic transmission appears unreliable: for most synapses, when an action potential arrives at an axon terminal, about half the time, no neurotransmitter is released and so no communication happens... Furthermore, when neurotransmitter is released at an individual synaptic release site, the size of the local postsynaptic membrane conductance change is also variable. Given the importance of synapses, the energetic cost of generating action potentials, and the evolutionary timescales over which the brain has been optimized, the high level of synaptic noise seems surprising."
Such a result (a very serious brain physical shortfall) is surprising only to those who believe that your brain stores your memories and that your brain makes your mind. Those who disbelieve such a thing may expect exactly such shortfalls to be repeatedly found.
In the brain, information would need to travel though very many synapses for even a short trip in the brain. What analogy can we give for such a setup, if each trip across a synapse occurs with low reliability? An analogy would be if I send an email from New York to Los Angeles, with the email passing through seven different computer servers, each of which transmits each particular character with a reliability of less than 50%. Under such a setup, it would be a lucky if a single word of my email got from New York to Los Angeles. There would be such message garbling and loss of characters that it would be a kind of like trying to read a pen-written message on a piece of paper that had gone through a washing machine seven different times.
There is another major reason for thinking that a brain should be unable to transmit any memory or thought signals. The reason is that most neurons have so many connections that there would be a signal overload preventing the reliable transmission of information.
Let us consider three different devices that effectively transmit information: a computer with a simple web browser, a radio and a television. There is one very important thing common to each of these inventions: each is arranged so that signals are received from only one source at a time. For example:
- A television set is arranged so that it can display TV signals from only one TV channel at a time.
- A radio is set up so that it can receive signals from only one radio station at a time.
- A computer with a simple web browser can display information from only one URL or web site at a time (let's ignore the not-so-simple web browsers that allow you to display different web sites in different tabs, and ignore the possibility of bringing up multiple instances of a web browser on the same computer).
Now, let's imagine what chaos would result if these things were not arranged in such a way:
- If a television set were arranged so that it displayed TV signals from five or ten TV channels at the same time, you would see and hear such a confusion of pixels and sounds that you would not be able to understand or enjoy any of the channels.
- If a radio were set up so that it received signals from five or ten different radio stations at a time, you would probably get such a confusion of sounds you would not be able to understand or enjoy anything coming from the radio.
- If a computer used a web browser that displayed five or ten web pages all at the same time, the browser's screen would show such a confusion of pixels that you would not be able to understand anything.
What we know about the physical arrangement of the brain tells us that the brain should suffer from the same type of problem described above. Since each neuron is bombarded with signals from many other neurons, most of which fire randomly, it should be impossible for neurons to accurately transmit thought or memory signals. It has been estimated that the average neuron has 7000 connections to other neurons. Every neuron should be like some malfunctioning TV set that picks up simultaneously 100 different TV stations at the same time, resulting in an incomprehensible jumble like the jumble shown above.
Below we see a diagram of a neuron. The yellow part is a myelinated axon, and the orange parts are dendrites.
"In fact, dendrites can be the site of AP initiation and propagation, and even neurotransmitter release. In several interneuron types, all functions are carried out by dendrites as these neurons are devoid of a canonical axon."
The wikipedia.org article on dendritic spikes tells us the following:
"In neurophysiology, a dendritic spike refers to an action potential generated in the dendrite of a neuron. Dendrites are branched extensions of a neuron. They receive electrical signals emitted from projecting neurons and transfer these signals to the cell body, or soma. Dendritic signaling has traditionally been viewed as a passive mode of electrical signaling. Unlike its axon counterpart which can generate signals through action potentials, dendrites were believed to only have the ability to propagate electrical signals by physical means: changes in conductance, length, cross sectional area, etc. However, the existence of dendritic spikes was proposed and demonstrated by W. Alden Spencer, Eric Kandel, Rodolfo Llinás and coworkers in the 1960s[1][2] and a large body of evidence now makes it clear that dendrites are active neuronal structures. Dendrites contain voltage-gated ion channels giving them the ability to generate action potentials."
Given such realities, we can describe a neuron as being subject to the most severe signal overload, like some TV set that is getting 100 channels at once, or some radio picking up 100 stations at once. Given the physical arrangement of neurons in brains, there is no chance that memory signals or thought signals could be reliably transmitted by neurons. Given many signal-slowing factors discussed at length here, it should be impossible for signals to travel through the human cortex at much faster than a snail's pace. Yet humans can think and recall with the greatest speed and accuracy. This is shown by cases such as actors playing the role of Hamlet, who recall more than 4000 lines with perfect accuracy, and at high speed. It is also shown by calculation savants who do extremely complicated mathematical calculations in their mind very quickly with perfect accuracy.
There are many historical cases of math prodigies that could calculate with incredible speed and accuracy. The passage below describes the blazing fast and very accurate calculation powers of Zerah Colburn:
"This child undertook, and completely succeeded in, raising the number 8 progressively up to the sixteenth power. And in naming the last result, viz.: 281, 474, 976, 710, 656, he was right in every figure. He was then tried as to other numbers consisting of one figure, all of which he raised (by actual multiplication, and not by memory) as high as the tenth power, with so much facility and dispatch that the person appointed to take down the results was obliged to enjoin him not to be so rapid. With respect to numbers consisting of two figures, he would raise some of them to the sixth, seventh and eighth power....He was asked the square root of I06,929, and before the number could be written, he immediately answered, 327. He was then required to name the cube root of 268,336,125, and with equal facility and promptness he replied, 645. Various other questions of a similar nature, respecting the the roots and powers of very high numbers, were proposed by several of the gentlemen present, to all of which he answered in a similar manner. One of the party requested him to name the factors which produced the number 247,483: this he immediately did by mentioning the numbers 941 and 263 — which, indeed, are the only two numbers that will produce it...One of the gentlemen asked him how many minutes there were in forty-eight years; and before the question could be written down, he replied 25,228,800; and instantly added that the number of seconds in the same period was 1,513,728,000."
The passage below tells us about the incredibly fast and accurate calculation speed of Jacques Inaudi, born in 1867:
"In his exercises of mental calculation, Mr. Inaudi is remarkable in two particulars, the complexity of his work and the rapidity with which he completes it. The greater number of questions given to him contain many figures. He will add in his head two numbers consisting of twelve figures each ; he will multiply two numbers composed of eight figures ; he will tell how many seconds there are in any promiscuously chosen number of years, months, days, and hours. These operations demand that he shall hold in his memory the exact problem and the partial solutions up to the time when the complete result is found. For such a considerable work as this, Mr. Inaudi gives an extremely short time, so short, indeed, as sometimes to produce the illusion of instantaneity. The following paragraph has been published concerning him. 'He adds in a few seconds seven numbers of eight or ten figures each; he subtracts one number from another each composed of twenty-one figures in less than a minute; he finds as rapidly the square root or the cube root of numbers consisting of from eight to twelve figures, if these numbers are perfect squares or cubes; it takes a little longer for the last-named work if there is a remainder necessitating a fractional part to the answer. He finds with incredible celerity the sixth or the seventh root of large numbers. He will multiply or divide in less time than it takes him to announce the results. As an example of what has been said, we give the following: He was asked the number of seconds in 18 years, 7 months, 21 days and 3 hours. The response was given in thirteen seconds.' "
The gap between the physical shortcomings of the brain and the realities of the most impressive human mental performance is like the gap between Earth and Jupiter. It is therefore foolish to continue the speech custom of saying that thinking and recall comes from brains, a custom that is an example of hollow hubris. It would be far wiser for us to say, "Humans have magnificent mental powers, and we don't know where they come from."
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