It is claimed by many that the synapses of the brain are an information storage system that stores our memories. To analyze whether this claim is credible, let us look at some common characteristics of information storage systems, and see whether synapses have any such characteristics.
Characteristic #1: An “alphabet” of symbolic tokens consisting of at least two types of tokens.
By an alphabet of symbolic tokens, I mean a set of symbols that can be used in the writing of symbolic information. Below are some examples:
- In English books, this alphabet of symbolic tokens consists of the letters of the alphabet and the various punctuation marks.
- In DNA this “alphabet” of symbolic tokens consists of the four types of nucleotide base pairs found in the DNA molecule (adenine, cytosine, thymine and guanine).
- In early Egyptian hieroglyphics, there was an “alphabet” of different pictogram symbols, each of which stood for some particular thing.
- In computers that store information using binary, there is an “alphabet” consisting of only two things: a magnetic mark standing for 1, and another magnetic mark (or absence of a mark) that stands for 0. Different combinations of such binary characters stand for particular letters in the alphabet.
Characteristic #2: A recurring tendency for one or more of these symbolic tokens to represent some particular thing.
In an information storage system such as a book it is not enough to simply have some set of symbolic tokens. There must also be some tendency for particular combinations of these tokens to represent some thing.
In the simplest type of information storage system, a single token represents one particular thing. For example, we may consider road signs as an information storage system in which a single token stands for one thing. On the left is a token standing for "a gas station," and on the right is a token standing for "pedestrians crossing."
In a more complex information storage system, it is ususally the case that particular combinations of tokens stand for some particular things. For example, in the English language the combination of the tokens "c," "a" and "t" stand for a cat.
Below we see a representation of the genetic code used by DNA. There are four tokens, A, C, T and G, which are the nucleotide base pairs adenine, cytosine, thymine and guanine. Particular combinations of these base pairs stand for particular amino acids. Looking at the chart below, and moving your eye from the center to the edge of the chart, you can see examples of these combinations and what they mean. For example, a combination of guanine (G), cytosine (C) and adenine (A) stands for the amino acid named alanine.
Characteristic #3: A sequence of these tokens in which particular tokens of the “alphabet” are repeated multiple times.
Below are some examples of this type of sequence:
- On a page of an English book, we have a long sequence of letters, and particular combinations of these stand for particular words.
- In a DNA molecule, there is a long sequence of nucleotide base pairs that collectively specify genetic information.
- On a computer hard drive, there are files consisting of long sequences of magnetic marks (the equivalent of 1's and 0's), that store information in particular types of computer files.
Characteristic #4: Some physical arrangement by which it is possible for the sequence of tokens to be read.
In order for you to have a meaningful information storage system, there must be some arrangement by which the stored information can be read, so that the stored sequence is retrieved or read. Imagine a system by which you spell out your text messages in scrabble blocks, and then toss the scrabble blocks to the bottom of a large trash can. That is not a workable information storage system, for it offers no hope of retrieving the original messages.
Some examples of systems that meet this characteristic are as follows:
- A book is an arrangement by which it is possible for a human to conveniently read all of the symbolic tokens in the book, in the correct sequence. The arrangement of tokens and the bindings of the pages make it easy for a sequential reading of the tokens.
- A DNA molecule is an arrangement by which it is possible to conveniently read all of the tokens (the nucleotide base pairs) in the correct sequence. The physical structure of the DNA molecule (a long string-like structure) make this sequential reading fairly easy.
- A tape playback and recording system such as a VCR had a physical arrangement by which a slowing turning tape passed by a read/write head, allowing magnetic marks on the tape to be read in a particular sequence.
Characteristic #5: Stability
Most of the information storage systems we use have stability. For example, once words have been printed on paper, the information will last for a very long time. And once something has been stored on a hard drive, the information can last in exactly the same state for years. Video tapes also last for many years. The information stored in DNA is also very stable. You still have basically the same DNA information in your cells that you had when you were born.
Do Synapses Have Any of These Characteristics?
Now let us look at the synapses of the brain, and ask: do they meet any of these five hallmarks of an information storage system? We will find no match to these characteristics merely by mentioning DNA in synapses, because synapses do not have DNA (DNA in the brain is found in neurons, but not in the synapses that connect neurons).
It seems that synapses do not have the first of these hallmarks. No one has ever discovered anything like an “alphabet” of symbolic tokens that could be used by synapses to store information. Some might argue that maybe the strength of a synapse acts like a symbolic token. But a synapse could have any of millions of different strengths, just like a muscle can have any of millions of different strengths. There doesn't seem to be any built-in characteristic of synapses allowing synapses to act as particular symbolic tokens, or to store symbolic tokens.
There is no evidence that synapses have the second of these characteristics. We can find no combinations of synapse tokens that stand for particular things, because no one has discovered any tokens at all in synapses.
It also seems that synapses do not have the third of these hallmarks of a system for storing symbolic information. No one has found any repetition of tokens in synapses.
It also seems that synapses do not have the fourth of these hallmarks of a system for storing symbolic information. There are countless synapses in the brain that exist in three-dimensional space, like tangled vines in a very densely packed jungle, or like strands of spaghetti in a huge pot filled with enough spaghetti to feed 100 children. There does not exist anything in the brain corresponding to a synapse reader that might sequentially read some stream of tokens in synapses if they happened to exist in synapses.
It also seems that synapses do not have the fifth of these hallmarks of a system for storing information. The proteins in synapses are short-lived, having an average lifetime of less than two weeks. It has been estimated the 3% of brain proteins are replaced every day. The paper here states, "Experiments indicate in absence of activity average life times ranging from minutes for immature synapses to two months for mature ones with large weights." So synapses lack the stablility that characterizes information storage systems.
It seems, therefore, that synapses have none of the main characteristics of information storage systems. Synapses no more resemble an information storage system than an outdoor lump of mud resembles an information storage system. So why do so many neuroscientists maintain that synapses are some storage system storing your memories? It's merely because they have committed themselves to the silly idea that memories must be stored in brains. It would be much better if neuroscientisists were to honestly say this: "We have found nothing in the brain that resembles a system for storing information that minds learn."
The scholar Robert Crookall has collected very many accounts of out-of-body experiences which you can read online here, here and here. The great similarities of such accounts, the fact that they are so often reported as spontaneously occurring in healthy, normal people, and the fact that things observed in such experiences are often verified are all indications that such accounts are not merely hallucinations. In such accounts we see people reporting no dimming of memory when they reported floating out of their bodies. Such accounts (senselessly ignored by almost all neuroscientists) provide a clue as to what is the real repository of memory: some soul or spiritual faculty that is very different from the brain.