A recent story at the LiveScience.com site has the title "Could we ever retrieve memories from a dead person's brain?" The story has many inaccurate claims, and fails to tell us the most important facts that are relevant to the question being considered. The subtitle of the article makes this claim: "Neuroscientists have identified the physical locations where memories are stored in the brain." No, they have not done any such thing, and the article fails to present any good evidence that any such thing was done.
We have this claim about a method to retrieve a memory from a brain:
"With today's technology, retrieving memories might go something like this. First, identify the set of brain cells, or neurons, that encoded a specific memory in the brain and understand how they are connected. Then, activate those neurons to create an approximate neural network, a machine learning algorithm that mimics the way the brain works."
This does not make any sense as an idea about how one would go about trying to start to read a memory from a brain. The first step in such a process would be to use microscopes to look for any speck of a trace of learned information in a brain. No one has ever succeeded in doing any such thing. Microscopic examination of brain tissue has never revealed a single word anyone ever learned. Microscopic examination of brain tissue has never revealed a single letter or character of anything anyone previously learned, and has never revealed a single pixel (an image dot) of anything anyone ever previously saw. Neural networks are a misnamed type of computer technology that do not actually mimic the brain and its physical shortfalls.
We have quotes by a neuroscientist (Don Arnold) doing some vague hand-waving and speaking as if he knew things he does not actually know. We read, "Memories are encoded by groups of neurons, Arnold said." That's the kind of vacuous, vague hand-waving that someone may use when he lacks any actual knowledge of how a brain could store memories. When people make big important-sounding claims that are not well-supported by evidence, they typically speak in a kind of vague, hand-waving way. For example, when asked where there existed the weapons of mass destruction that the US claimed were in Iraq before invading it in 2003, US defense secretary Donald Rumsfeld said this:
"We know where they are. They're in the area around Tikrit and Baghdad and east, west, south and north somewhat."
Such weapons of mass destruction were never found in Iraq in 2003 or in the next twenty years.
Reminding me of the Rumsfeld statement, the LiveScience article claims that long-term memories are formed in the hippocampus, a claim not backed up any robust evidence. The main research paper on the hippocampus and memory is the paper "Memory Outcome after Selective Amygdalohippocampectomy: A Study in 140 Patients with Temporal Lobe Epilepsy." That paper gives memory scores for 140 patients who almost all had the hippocampus removed to stop seizures. Using the term "en bloc" which means "in its entirety" and the term "resected" which means "cut out," the paper states, "The hippocampus and the parahippocampal gyrus were usually resected en bloc." The "Memory Outcome after Selective Amygdalohippocampectomy" paper does not use the word "amnesia" to describe the results. That paper gives memory scores that merely show only a modest decline in memory performance. The paper states, "Nonverbal memory performance is slightly impaired preoperatively in both groups, with no apparent worsening attributable to surgery." In fact, Table 3 of the paper informs us that a lack of any significant change in memory performance after removal of the hippocampus was far more common than a decline in memory performance, and that a substantial number of the patients improved their memory performance after their hippocampus was removed.
The LiveScience article tells us, "Other parts of the brain store different aspects of a memory, like emotions and other sensory details, according to the Cleveland Clinic." We are referred to a page on some web site of the Cleveland Clinic that has no named author, and is the kind of article that you might get if you asked ChatGPT about how memory works. That Cleveland Clinic page does not actually make the claim that the LiveScience article attributes to it. The Cleveland Clinic does not claim that different aspects of a memory are stored in different places, but merely claims that other parts of a brain "participate in memory processes."
The LiveScience article then makes a false claim, repeating a groundless achievement legend. It states this:
"Neuroscientists have identified engrams in the hippocampuses of mouse brains. For instance, in a 2012 study published in the journal Nature, researchers found the specific brain cells associated with a memory of an experience that induced fear."
No, there does any exist any robust evidence for engrams (neural storage places of memories) in any animal. The paper the LiveScience article links to is the 2012 paper “Optogenetic stimulation of a hippocampal engram activates fear memory recall.” That is a very low-quality paper guilty of several bad examples of Questionable Research Practices. We see in Figure 3 of that paper that inadequate sample sizes were used. The number of animals listed in that figure (during different parts of the experiments) are 12, 12, 12, 5, and 6, for an average of 9.4. That is not anything like what would be needed for a moderately convincing result, which would be a minimum of 15 or 20 animals for each study group, and probably more. The experiment relied crucially on judgments of fear produced by manual assessments of freezing behavior, which were not corroborated by any other technique such as heart-rate measurement. All mouse research papers relying on "freezing behavior" judgments are junk-science papers, for reasons I discuss in my post here, "All Papers Relying on Rodent 'Freezing Behavior' Estimations Are Junk Science." The 2012 study does not describe in detail any effective blinding protocol, which is another bad defect. The study involved stimulating certain cells in the brains of mice, with something called optogenetic stimulation. The authors have assumed that when mice freeze after stimulation, that this is a sign that they are recalling some fear memory stored in the part of the brain being stimulated. What the authors neglect to tell us is that stimulation of quite a few regions of a rodent brain will produce freezing behavior. So there is actually no reason for assuming that a fear memory was being recalled when the stimulation occurs.
There does not exist any observational or experimental support for the existence of engrams (memory storage places) in any animal. Some papers have claimed to have produced such evidence, but their claims do not stand up to critical scrutiny. Papers claiming to produce such evidence are generally guilty of multiple types of Questionable Research Practices such as way-too-small study group sizes, lack of a blinding protocol, and the use of one or more unreliable techniques for judging memory performance.
The LiveScience article then gives us this bit of excuse-making for why no one has ever read a memory from a brain: "The retrieval of a dead person’s memories is further complicated because the discrete parts of a memory are dispersed throughout the brain; for instance sensory details that can also be stored in the parietal lobe and sensory cortex." This is an appeal to the theory that a single memory is stored not in one tiny part of the brain but in multiple scattered parts of the brain. There is no evidence for such a theory, and the theory makes things worse for the person claiming that the brain stores memories, for reasons I discuss in my post "Why the 'A Memory Is Stored Throughout the Brain' Idea Makes Things Much Worse." If a single memory were to be stored in multiple locations in the brain, then finding all of those locations and assembling them instantly (in a brain without any addresses or indexes or sorting) would be something even more impossible to explain than imagining that the memory existed in a single spot that was instantly found.
Giving us its second example of claiming a cited source said something that it did not actually say, the LiveScience article states, "Neurons within a given engram are connected through synapses, the spaces between neurons where electrochemical signals travel, according to the National Library of Medicine." The page that it links to does not ever use the word "engram," and does not refer to either memory or learning. The LiveScience article claims that according to the neuroscientist Arnold, "there is evidence that memories move to different locations as they are consolidated in the brain." There is no robust evidence of any such thing. Neuroscientists have no credible evidence of memories being stored in any part of the brain of any organism, and they do not have any decent evidence of a memory moving around from one part of the brain to another.
Arnold is quoted as saying, "You get this sort of cascade of neurons that encode these different things, and each one of them is connected in this engram." That is hand-waving. Scientists lack any robust evidence of any such thing as an engram or an encoding of learned information or experiences in the brain. No scientist has a credible detailed theory of how such encoding could occur. An ocean of difficulties arises when you start to consider the endless problems that would arise when trying to translate human learned knowledge and experiences into brain states through any imaginable system of encoding. Part of the problem is the extreme variety of things that people can learn and experience (concepts, facts, theories, visual experiences, auditory experiences, smell experiences, taste experiences, pain experiences, touch experiences, and emotional reactions), meaning there could be no simple encoding scheme (something as simple as the genetic code) that could handle even a tenth of all the types of memories people can form.
We have no discussion of some of the chief facts relevant to the topic discussed. Some of these facts are below:
(1) Human brain tissue has already been exhaustively studied at very high microscopic resolutions. My post "They Stored and Studied Thousands of Brains, But Still Failed to Show Brains Store Memories" discusses how places such as the Lieber Institute have microscopically studied thousands of brains, most of which were preserved very soon after death. The same post describes how Denmark's University of Odense has stored more than 9000 brains, microscopically examining a large fraction of them. Very much healthy brain tissue just-extracted from living patients has been microscopically examined, because normal brain tissue is often extracted from epilepsy patients when operations are done to prevent intractable seizures resistant to medicine. (2) Despite all of that microscopic examination, no one has ever found the slightest trace of any learned information by microscopically examining a brain. Microscopic examination of brain tissue has never revealed a single letter or character of anything anyone learned, and has never revealed a single pixel of anything anyone ever saw. It isn't just that no one ever found anything like "The US has 50 states" by microscopically examining brain tissue; it's that no ever found a U or an S from microscopically examining brain tissue.
(3) The discovery of a bit of learned information from microscopically examining brain tissue is something that would be many times easier to do than the "recreation of a full memory" imagined by the LiveScience article, but neither of these things has occurred.
(4) Modern microscopic techniques are powerful enough to discover traces of learned information in the brain if they existed, but no such discovery has occurred.
(5) Nothing in the brain looks like any type of mechanism for storing learned information or storing memories. Nothing in the brain looks like any type of apparatus for writing learned information.
(6) Nothing in the brain looks like any type of mechanism for reading a stored memory. We can imagine how some organism's brain might physically look like something capable of reading information from a particular spot, by means of something like a moving cursor or moving reading component. The brain has no such thing, and the brain has no moving anatomical parts.
(7) The places claimed to be sites of brain memory storage (synapses) are unstable places of high molecular turnover, where all the proteins last for only a few weeks or less. There is no credible theory of how places so unstable could be storage places for memories that can reliably last for 60 years.
(8) There is nothing in the brain that looks like learned information stored according to some systematic format that humans understand or do not understand. Even when scientists cannot figure out a code used to store information, they often can detect hallmarks of encoded information. For example, long before Europeans were able to decipher how hieroglyphics worked, they were able to see a repetition of symbolic tokens that persuaded them that some type of coding system was being used. Nothing like that can be seen in the brain. We see zero signs that synapses or dendritic spines are any such things as encoded information.
(9) Many humans can remember with perfect accuracy very long bodies of text, but synapses in the brain do not reliably transmit information. An individual chemical synapse transmits an action potential with a reliability of only 50% or less, as little as 10%. A recall of long bodies of text would require a traversal of very many chemical synapses. A scientific paper says, "In the cortex, individual synapses seem to be extremely unreliable: the probability of transmitter release in response to a single action potential can be as low as 0.1 or lower." Below is a diagram from the paper "Materials Advances Through Aberration-Corrected Electron Microscopy." We see that since the time the genetic code was discovered about 1953, microscopes have grown very many times more powerful. The A on the left stands for an angstrom, a tenth of a nanometer (that is, a ten-billionth of a meter).
Currently the most powerful microscopes can see things about 1 angstrom in width, which is a tenth of a nanometer. How does this compare to the sizes of the smallest units in brains? Those sizes are below:Width of a neuron body (soma): about 100 microns (micrometers), which is about 1,000,000 angstroms.
Width of a synapse: about 500 nanometers, about 5000 angstroms. When you search for "width of a synapse," you will commonly get a figure of 20 to 40 nanometers, but that is the width of the synaptic cleft, the gap between two synapses or between a synapse and a dendrite. The full head is much wider, as you can see from the page here.
Width of a dendritic spine: about 50 to 500 nanometers, about 500 to 5000 angstroms.
Length of a dendritic spine: the site here says, "the thin spine neck, which connects the spine to the main dendritic branch, has lengths between 0.04 and 1 μm [microns] and has 'door knob'-shaped head structures with diameters that between 0.5 and 2 μm [microns]." That length dimension is between 400 and 10,000 angstroms; and that head diameter is between 500 and 20,000 angstroms.
The visual below (from the page here) shows an electron microscope image of a synapse. The width of the synaptic head is more than 500 nanometers (nm). We see nothing that looks like any kind of storage of human learned information. The neurotransmitters inside the spherical vesicles are short-lived chemicals that don't even last a week.
Below we see a closeup electron microscope photograph of some dendritic spines which are 500 nanometers (5000 angstrom) wide, from the scientific paper here "Ultrastructural comparison of dendritic spine morphology preserved with cryo and chemical fixation," by Tamada et. al. We see nothing that looks anything like stored learned information or stored memory information. Do a Google search for "diagram of dendritic spine head" and you will get diagrams that look like nothing that could be any system for storing information long-term. The diagrams will show that such dendritic spine heads are just bags of short-lived proteins and chemicals. A few of these diagrams may show actin filaments looking a bit like a structure, but searching for "lifetime of actin filaments" you will be told that such filaments have lifetimes of only minutes.
The only thing in the brain smaller than the structures shown above are protein molecules. But we know a reason why protein molecules cannot be a storage place for memories that can last for 50 years. The reason is that the average lifetime of a brain protein molecule is 1000 times shorter than the longest length that people can remember things. Proteins in the brain have an average lifetime of two weeks or shorter.
A scientific paper states this:
"Experience-dependent behavioral memories can last a lifetime, whereas even a long-lived protein or mRNA molecule has a half-life of around 24 hrs. Thus, the constituent molecules that subserve the maintenance of a memory will have completely turned over, i.e. have been broken down and resynthesized, over the course of about 1 week."
Research on the lifetime of synapse proteins is found in the June 2018 paper “Local and global influences on protein turnover in neurons and glia.” The paper starts out by noting that one earlier 2010 study found that the average half-life of brain proteins was about 9 days, and that a 2013 study found that the average half-life of brain proteins was about 5 days. The study then notes in Figure 3 that the average half-life of a synapse protein is only about 5 days, and that all of the main types of brain proteins (such as nucleus, mitochondrion, etc.) have half-lives of 15 days or less. The 2018 study here precisely measured the lifetimes of more than 3000 brain proteins from all over the brain, and found not a single one with a lifetime of more than 75 days (figure 2 shows the average protein lifetime was only 11 days).
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."
Clearly the resolution of the most powerful microscopes is powerful enough to read memories stored in neurons or synapses or dendritic spines, if such memories existed. And more than 10,000 brains have been microscopically studied in recent years. The failure to microscopically read any memories from human brain tissue is a major reason for thinking that brains do not store human memories. If memories were stored in the brain, roughly about the year 1960 humans would have been able to read learned information stored in brains, when the resolution of microscopes reached about 10 angstroms. If memories were stored in the brain, we would have discovered irrefutable evidence of such a thing about 60 years ago. The total failure to find a single speck of learned information in the brain by microscopic examination is one of the strongest reasons for disbelieving in a brain storage of memories.
I predict with great confidence that microscopes will never find the slightest trace of learned information in the human brain, because memories are not stored in brains. But we may have in the future some occasional "false alarm" claims to have accomplished such a thing, claims that are not supported by robust evidence. Neuroscientists have often been guilty of both smoke-and-mirrors trickery and pareidolia, when someone claims to see something that isn't really there, typically because he is eagerly scanning large bodies of random, ambiguous data, eagerly hoping to find something that isn't really there. So we may see some pareidolia in which a neuroscientist claims to see a memory by microscopic examination. Such a thing will be like some fervent believer in animal ghosts in the clouds examining thousands of photos of clouds, and claiming that this one or that looks like the shape of an animal.
Note that in the LiveScience article there is not any mention of any scientist sounding hopeful about a possibility of discovering stored information in the brain.
This week I was reminded of the ability of the human mind to retain memories for 50 years, contrary to what we would expect from the high molecular turnover in brains. I had a recollection which proved the ability of the mind to recall very old memories that have not been recalled in half a century. For some reason I recalled a book I had read about 50 years ago, and never since: the science fiction book "Galaxies Like Grains of Sand" by Brian Aldiss. I remembered some lines from the book. I wrote them down on paper like this:
"The mirror of the past lies shattered. The fragments you hold in your hand."
After I wrote this recollection of something I had not read, thought of or heard quoted in fifty years, I borrowed the book on www.archive.org. I see that the lines were these (almost exactly as I remembered them)
"The long mirror of the past is shattered...Only a few fragments are left, and these you hold in your hand."
For a person like me, the mirror of the past is not shattered, but remains well preserved after 60 years, contrary to what we would expect if memories were stored in brains with such high molecular turnover and such constant remodeling of synapses and dendritic spines.
Below is a quote on the same topic from an earlier post discussing why brains cannot be the storage place of very old memories:
"I know for a fact that memories can persist for 50 years, without rehearsal. Recently I was trying to recall all kinds of details from my childhood, and recalled the names of persons I hadn't thought about for decades, as well as a Christmas incident I hadn't thought of for 50 years (I confirmed my recollection by asking my older brother about it). ...Upon looking through a list of old children shows from the 1960's, I saw the title “Lippy the Lion and Hardy Har Har,” which ran from 1962 to 1963 (and was not syndicated in repeats, to the best of my knowledge). I then immediately sung part of the melody of the very catchy theme song, which I hadn't heard in 53 years. I then looked up a clip on a youtube.com, and verified that my recall was exactly correct. I also recently recalled 'The Patty Duke Show' from the 1960's, a show I haven't seen in 50 years, and recalled that in the opening title sequence we saw Patty walking down some stairs. I looked up the title sequence on www.youtube.com, and verified that my 50-year-old memory was correct. This proves that a 53-year-old memory can be instantly recalled."
The prediction I make here is just one of several predictions in my 2019 post "Contrarian Predictions Regarding Biology, the Brain and Technology." So far my predictions in that post are holding up very well.
