The Navigation Argument Against the Idea That Your Brain Stores All Your Memories

Neurologists like to assume that all your memories are stored in your brain. But there are actually quite a few reasons for doubting this unproven assumption, including the research of scientists such as Karl Lashley and John Lorber. Their research showed that minds can be astonishing functional even when large parts of the brain are destroyed, either through disease or deliberate surgical removal. Lorber documented a case of a person who was doing well in his college studies, even though the great majority of his brain had been destroyed by disease. Some children with brain problems sometimes undergo an operation called a hemispherectomy, in which half of their brain is removed. An article in Scientific American tells us, “Unbelievably, the surgery has no apparent effect on personality or memory.”

Given such anomalies, we should give serious consideration to all arguments against the claim that your brain is storing all your memories. In my previous post, I presented one such argument, based on the apparent impossibility of the brain ever naturally developing all of the many encoding protocols it would need to store the many types of things humans remember. In this post I will present another argument against the claim that your brain stores all your memories. This argument, which I call the navigation argument, is simpler than the argument in my previous post.

The navigation argument can be simply stated like this: a long-term memory cannot be stored in some particular part of the brain, because there could be no way in which your brain could ever instantly find the location where such a memory was stored.

Let's consider a simple case. You hear the name of a movie star. You then instantly recall what that person looks like, and see a faint image of that person in your “mind's eye.” But how could this ever happen, if the memory of that person is stored in some particular part of your brain? In such a case, you would need to know or find the exact place in the brain where that memory was stored. But there would be no way for your brain to do such a thing. It would be like trying to find one particular needle in a skyscraper-sized stack of needles.

Let's try to imagine some ways of getting around this difficulty, and consider whether they are viable. One possibility is that a memory hypothetically created in the brain might have some type of unique positional identifier, something rather than a GPS coordinate or a longitude/latitude coordinate (although it might be something like a 3D coordinate). When a visual memory was created, the brain might associate this coordinate with some memory cue (such as the person's name). So, for example, when you hear the phrase “White House” maybe your brain subconsciously retrieves some 3D coordinate allowing you to find where you have stored in your memory an image of the White House in Washington, D.C. The visual below illustrates the idea.

But there are three reasons why this doesn't work as an explanation. The first is that there is no way that the brain could ever know what the 3D coordinate was for some particular spot where a new memory was created. For example, if a brain is creating a new memory at a location with an X coordinate of 23.23342, a Y coordinate of 45.34245, and a Z coordinate of 33.3293, the brain would have no way of knowing that the memory was being created at that exact location. A second reason is that even if there was some brain storage area storing the location coordinates for particular memories, there would still be the question of: how could the brain instantly find the correct spot in such a cue storage area to find where these coordinates were? Since your brain can store millions of different memories, we must imagine that this cue storage area would also have millions of items. There is no reason we can think of why you would be instantly be able to find the exact part of this cue storage area that would have the coordinate needed to locate the appropriate memory. Third, there is the difficulty that even if the brain had the physical coordinates at which the memory stored, it would have no way of navigating to such a coordinate.

To try to make things a little better, let's get rid of this idea of a coordinate system. Let's imagine that there is some kind of cue memory area with direct neural connections leading to the spots where memories are formed. So then if you hear a particular name, your brain merely finds that name in the cue storage area, and then follows this little neural connection (rather like a wire or telephone line) to where the memory is stored. The visual below illustrates the idea. 

 

But this still does not give us a plausible answer as to how you could recall a memory stored in a particular spot in your brain. For one thing, there would be the difficulty of explaining how this wiring-up was occurring. It doesn't seem plausible to maintain that each time you memorize something, you are adding an entry in two different storage areas of your brain, and also instantly creating a neural wire or line connecting only these two. That seems like too much work and coordination to be occurring so quickly. We have no evidence that coordinated changes occur in two different areas of the brain when a memory is stored. While we know that connections can gradually form between neurons, this isn't something that can instantaneously occur to link separate areas of the brain when a memory is created.

You would also still have the previously mentioned problem of how your brain could instantly find the correct spot in this cue storage area where these cues are located. Since your brain can store millions of different memories, we must imagine that this cue storage area would also have millions of items. There is no reason we can think of why you would be instantly able to find the exact part of this cue storage area that would have the direct wire or neural connection needed to locate the appropriate memory in the visual storage area.

So we seem to be getting nowhere trying to imagine how the brain could allow you to instantly recall memories. Let's try looking at how computers are able to quickly retrieve data. Perhaps that might offer some clue.

One basic technique computers use to speed retrieval access is physical sorting. The same technique is used by a simple file cabinet in which the files are alphabetically sorted. But we cannot believe that the brain uses physical sorting. A mass of microscopic neurons (rather like a city-sized blob of tangled spaghetti that has been shrunk) is not something in which physical sorting is possible. All the different brain connections make physical sorting impossible, just like you can't sort a giant ball of tangled string into different parts (unless you disassemble and reassemble). A brain structured totally different from the human brain might be able to use physical sorting, but not the human brain. We have zero evidence that neurons are physically sorted. 

 Neurons cannot be physically sorted or physically grouped

Another basic technique computers use to speed retrieval access is physical grouping, such as when different types of information are placed in different computer files. The same technique is used by a simple file cabinet in which different types of information are put into different manila files. But we cannot believe that the brain uses physical grouping. A mass of neurons filled with connections between neurons is not something in which physical grouping is possible. A brain structured totally different from the human brain might be able to use physical grouping, but not the human brain. When we look at the brain, we see no evidence that a physical grouping of neurons is occurring. Neurons are not arranged into little clusters like stars are arranged into galaxies.

In short, it seems physically impossible that a brain structured such as ours could ever instantly retrieve memories, if such memories were stored in particular parts of the brain. There is no physical mechanism that can explain how this could occur in the human brain. 

One way to try to resist such an argument is to claim that a particular memory is not stored in a particular place in the brain, but throughout the brain. If that were true, there would be no problem of the brain trying to find just one particular spot where a memory is stored. But a human mind has many thousands or millions of memories. We can hardly believe that each of these is stored throughout the brain. If my memory of my first kiss was stored throughout my brain, that would leave no space for the thousands or millions of other memories I have. We may also note how absurd it is to imagine that, for example, I have stored throughout all the neurons of my brain some trivial image such as the image of SpongeBob Squarepants.

It is sometimes maintained that a specific memory is stored not in one little spot in the brain, or throughout the entire brain, but is scattered across several different places. This does nothing to make the retrieval of a memory from a brain more plausible. You do not lessen the difficulty of “how could the brain know where to find one specific spot where a particular memory is stored” if we assume that the memory is read from five or ten different specific places, because there is still the problem of how the brain could find those specific locations. Similarly, there would be no way for someone to find some information very quickly if it is in some book among many thousands of books in a library that all had no title on their cover; and it would be even harder to get such information quickly if the information was scattered across five or ten such books in such a library. Lacking any coordinate system or labeling system, a brain storing memories would be like such a library.

In a blog post, a neurologist has replied to the type of argument being made here (after it had been made by another writer). The neurologist writes: “You don’t have to know (nor does your brain) where in your physical brain a memory is located, because you can access that memory simply because it is integrated with so many other memories.”

This reasoning is fallacious. Using similar reasoning, I could argue that I don't have to know the phone number of someone in California to telephone that person, because all of the telephones are integrated with each other in a telephone network. But that's erroneous. You do have to know someone's phone number to instantly access that person's phone. To instantly access a memory such as occurs when you recall a face after seeing a name (or vice versa), the brain would absolutely need to know where that memory is stored (or have some mechanism for instantly locating that precise brain location), if the memory was stored in one particular location in the brain. But no one can give any explanation of how the brain could know such a thing, or how the brain could instantly find the correct memory. I may note that when you recall a face instantly after seeing it, it is not at all a case of one memory leading you to find another. We absolutely cannot use “integration of memories” to explain such a thing.

The complete lack of any workable theory for how memory recall can occur so quickly is admitted by neuroscientist David Eagleman, who states:

Memory retrieval is even more mysterious than storage. When I ask if you know Alex Ritchie, the answer is immediately obvious to you, and there is no good theory to explain how memory retrieval can happen so quickly.

The reasoning above suggests that our neurologists will never be able to solve the problem of how the mind is able to recall things so quickly. The human brain is simply not structured the way a physical system would need to be structured in order for an instantaneous recall of detailed complex memory information to occur from one particular storage location in the brain. The impossibility of explaining how instant memory recall occurs is a powerful reason for believing that long-term memories are not stored in your brain. We must postulate that the human mind is part of some reality that transcends the human nervous system. Call it a soul reality, or call it a spiritual reality – it is something that must go beyond the human brain.

As we will see in my next post, there is another reason for drawing the same conclusion: the fact that there is no viable mechanism that explains how the brain can be storing very long-term memories. In my next post, I will look at the most common mechanistic theory of how the brain stores long-term memories, and explain why it is untenable (citing neurologists themselves who have given powerful reasons why such a theory is untenable). The theory in question is untenable because it tries to explain long-term memories by appealing to a “shifting sands” type of mechanism that is so impermanent and fast-decaying that it is completely unsuitable for explaining human memories that can last for 50 years (and cannot even explain human memories that last for two years). 

Postscript: Given the complete lack of any coordinate system in the brain by which the exact locations of neurons can be specified, the brain can be compared to these things:
(1) the US phone system if no one's phone number had ever been published;
(2) a vast post office with countless post office boxes, none of them numbered;
(3) a city in which none of the streets were named, none of the buildings had an outside identifier, none of the apartments had apartment numbers, and none of the houses had street numbers;
(4) a vast library containing thousands of books, none of which have any title on their cover, chapter titles, or page numbers.
 
Imagine how hard it would be in any of such things to navigate to a precise location  -- a particular post office box, a particular phone,  a particular apartment in the city, or a particular book in the library.  That's the kind of situation that should exist in a brain storing abundant memories, because there is no coordinate system in a brain, and neurons don't have neuron numbers or something like a brain longitude and latitude.  Instantaneous recall of obscure memories should be impossible if our memories are stored in brains. The fact that we routinely perform such instantaneous recalls is strong evidence our memories are not mainly stored in brains.

The Encoding Protocols Argument Against the Idea That Your Brain Stores All Your Memories

Most neurologists assume that your memories are stored in your brain. But the workings of memory are a great mystery. We have no understanding of any exact mechanism by which memories could be stored in the brain. Contrary to hyped claims and certain unconvincing studies with a dubious methodology, there is no convincing evidence that particular memories are stored in particular places in the brain.

Scientists such as Karl Lashley spent decades looking for particular parts of the brain where particular memories were stored, and could not find them. Lashley's research discovered all kinds of results hard to reconcile with the claim that particular memories are stored in particular parts of the brain – such as rats that suffered almost no loss of ability to remember some kinds of mazes, even when up to 50% of their brains were removed. The doctor John Lorber discovered astonishing cases such as a student who was doing very well in college, even though almost all his brain had been destroyed by disease. More recently, there was the case of a French civil servant who was astonished to discover that almost all of his brain had been destroyed by disease. This hadn't stopped him from doing his government job.

The evidence from memory research is sufficiently muddied and unclear that there is definite room for an argument against the idea that your brain stores all your memories. I will now present such an argument. I can summarize the argument as follows: when we analyze in detail what a brain would need to do on a low-level in order to store memories, we find that the brain would need to use a whole set of encoding protocols so sophisticated that they could not have naturally arisen.

To explain this argument I must first explain what is meant by an encoding protocol. To understand the idea of encoding memories, you have to realize that there is pretty much no such thing as “just storing” information. Almost every type of information that we know of involves some type of encoding. Encoding is when information is stored using some particular system of representation.

Let me give some examples to clarify the idea. Consider the storage of written words. A system of symbols (the alphabet) may be written to store the words. Each time someone types the letters “cat” to mean a cat, that person is using an encoding protocol known as the alphabet.

When words are stored on a computer or smartphone, multiple levels of encoding are involved. First, there is the alphabetic encoding. Then there is what is called an ASCII encoding. The individual letters are converted to numbers, using an ASCII table that signifies how particular letters will be stored as particular numbers. Then there is a binary encoding by which numbers such as 34 written in the base 10 system are converted to a series of 1's and 0's such as 100101101. 

ASCII is an encoding protocol representing letters as numbers

We see in the diagram below three different types of encoding going on when the word “cat” is stored on a computer.

When an image is stored on a computer, there are also multiple types of encoding going on. The image is broken down into a grid of pixels; each pixel is translated into a number indicating a particular shade of color; then those numbers are translated into binary form that is ideal for storing on a computer hard drive. 

 Encoding of a visual image

Now let us consider how the brain might store memories. Just as there is pretty much no such thing as “just storing” information on a computer, without using some type of encoding, there could be no such thing as “just storing” a memory in the brain. If we are to imagine that the brain stores memories, we must imagine that the brain somehow does encoding to get the memory stored to the brain.

It is hypothesized that the brain might store memories using things such as molecules or nerve cell electrical states. But just as information must always be encoded before it can be stored on a hard drive, there would need to be encoding before any memory information could be stored in something like molecules or electrical states. For example, we cannot imagine that a molecule would ever directly store some letters that we could see using an electron microscope that might show a tiny little “Y” and “G” on a molecule. Nor can we imagine that if we scan your brain with an electron microscopic, we would find tiny images representing scenes from your life, images that could directly be seen in the electron microscope's closeup photos. Instead, if the brain stores memories, there would need to be some low-level encoding causing the memories to be stored in a way that can efficiently be represented by molecules or nerve cell electrical states or neuron connections.

But here a very great difficulty arises. The problem is that human memories include an incredibly diverse collection of things. Consider only a few of the types of things that can be stored in a human memory:

• Memories of daily experiences, such as what you were doing on some day
• Facts you learned in school, such as the fact that Lincoln was shot at Ford's Theater
• Sequences of numbers such as your social security number
• Sequences of words, such as the dialog an actor has to recite in a play
• Sequences of musical notes, such as the notes an opera singer has to sing
• Abstract concepts that you have learned
• Memories of particular non-visual sensations such as sounds, food tastes, smells, pain, and physical pleasure
• Memories of how to do physical things, such as how to ride a bicycle
• Memories of how you felt at emotional moments of your life
• Rules and principles, such as “look both ways before crossing the street”
• Memories of visual information, such as what a particular person's face looks like

Now given all these types of things that can be remembered, there would seem to be two possibilities if the brain is storing all your memories:

Possibility 1: The brain has a single “all-purpose” encoding system that somehow works for all of these extremely diverse types of memories.

Possibility 2: The brain uses many different types of encoding protocols; and when it is time to store a memory, the brain somehow figures out the appropriate encoding protocol to use.

The problem is that neither of these options seem credible.

Given the incredible diversity of the various types of memories listed above (which is not even a complete list of all the types of memories that can be stored), it seems unreasonable to imagine that there could ever be any universal “all purpose” encoding system that could work with things as dissimilar as memories of smells, miscellaneous learned facts, principles of living, and long sequences of musical notes or letters. It would seem that many of the types of memories would require their own distinctive type of encoding system.

But it also seems very hard to imagine that the brain could encode memories by using a variety of encoding schemes, and selecting the appropriate encoding scheme to use at the moment that a memory is stored. The problem with that idea is that it requires for us to believe that the brain subconsciously is able to instantly figure out what type of information a memory is, and to then select the appropriate encoding scheme. That would seem to involve some incredibly sophisticated instantaneous analysis, and how could such a thing all be going on subconsciously?

It seems very hard to believe, for example, that if you meet some young woman at a party, and ask for her phone number, that behind the scenes your brain subconsciously is acting like this: well, well, I have a face to store, so let me use the “visual data encoding system” I have stored in such and such a place; and for the phone number let me use the “numerical sequence encoding system” I have stored in some other place; and to store her name let me use the “alphabetic data encoding protocol” I have stored in some other place; and to store the scent of her perfume, let me use the “smell encoding system” I have stored in some other place. All this classification and selection seems to be far too much work to be done subconsciously. Nor can we believe that a selection of encoding systems occurs consciously, for we never (or virtually never) have any conscious thoughts about what type of encoding protocol to use when we remember things.

In short, explaining how encoding could work on a low-level to store memories is a practical nightmare. Our psychologists say that some encoding is going on when memories are stored, but none of them has succeeded in presenting a plausible and detailed description of exactly how such encoding could work. When discussing the issue, psychologists and neurologists will typically combine speculation and tangential findings in a way that will skillfully hide their lack of any mechanism for how such encoding could occur.

When we consider the storage of multifaceted or abstract ideas, it is hard to think of how encoding could possibly work. How, for example, could your brain possibly do some encoding that would represent your mother or the concept of treating people equitably or the idea of the United States as some series of electrical states in the brain, some molecular states, or some combination of the two? We cannot imagine any such encoding.

How can we escape such difficulties? We can abandon the materialist idea that your memories are all stored in your brain. We can believe that our minds are some mysterious spiritual or soul reality, and that memories are part of such a reality. If we no longer have to believe that all memories are being stored in particular parts of the brain, all of the difficulties in explaining memory encoding conveniently disappear. We could still continue to believe that our brains store some things that are rather loosely called memories, such as what are called motor memories, remembrance of how to do particular movements of parts of the bodies. But by believing that conceptual memories and experiential memories are part of some non-physical reality that the human mind is part of, we free ourselves from the seemingly impossible burden of having to explain how the brain could possibly have naturally developed encoding protocols that could represent such things.

We know of one encoding protocol that is definitely used by living things: the genetic code. This is the protocol by which particular amino acids are represented by particular trios of nucleotide bases. The genetic code is an encoding protocol roughly as complicated as the ASCII protocol.

The genetic code

But how did this genetic code ever appear naturally? This is a major explanatory nightmare for naturalists. The natural origin of the genetic code has never been plausibly explained.

But consider how great are the difficulties of a materialist who believes all of your memories are stored in your brain. It would seem that for memories to be stored in the brain, it would have to be that there naturally arose not just one sophisticated encoding protocol (the genetic code), but many such sophisticated encoding protocols –all the different encoding protocols needed to store our many different types of memories in our brains. The theorist who claims that your memories are all stored in your brain is like someone burdened by ten albatrosses hanging from his neck, each albatross being the burden of explaining how one of these encoding protocols could have naturally arisen. I haven't even mentioned the issue of decoding, which further doubles the explanatory burden of someone believing that the brain stores all your memories, by requiring such a person to believe that the brain also has a whole set of decoding protocols that are mirror images of the encoding protocols, decoding protocols used in retrieving stored memories that had been encoded using the encoding protocols.

It can be powerfully argued that if we have to believe that all of these sophisticated encoding protocols exist, this should make it ten times more difficult to explain how humans naturally came to exist. But there is an alternative. By believing that the mind has a spiritual reality or soul reality, we free ourselves from the burden of having to explain all these sophisticated encoding protocols that we would need to store all our memories in the brain – for we no longer have to believe that our memories are all stored in the brain.

The argument I have given here is only one of several arguments that can be made against the claim that your brain is storing all your memories. In my next post I will discuss another argument against such a claim --- what I will call the navigational argument. This is the argument that if your brain were to store an experience memory or a conceptual memory in some particular place in your brain, your brain would never be able to instantly find the location where that memory was stored. In still another post, I will argue that the brain lacks the biological features we might expect to find in a system capable of storing complex experience memories for 50 years, and that facts such as synapse turnover undermine attempts to explain how the brain could be storing experience memories for 50 years.

Pratfalls of the Physicists: Lessons of the SUSY and Diphoton Blunders

Ever since the atomic bomb was invented, some people have regarded physicists as almost godlike figures. But two examples I will discuss below show that large number of physicists are capable of falling flat on their faces.

What is called the 750 GeV diphoton excess is an observational blip reported in 2015 by scientists working with the Large Hadron Collider, the world's largest particle accelerator. When the diphoton excess was reported in 2015, scientists began to speculate that it might be a sign of physics beyond the Standard Model of physics.

But today scientists poured cold water on such thinking. As discussed here, they reported that the diphoton excess is just a random data blip that doesn't indicate anything important. David Charlton, leader of the ATLAS experiment at the Large Hadron Collider, reported the following:

There was a lot of excitement when we started to collect data. But in the [latest results] we see no sign of a bump, there's nothing. It is a pity because it would have been a really fantastic thing if there had been a new particle.

But (as mentioned here) our impatient theoretical physicists have already written 500 scientific papers pontificating on the deep significance of the diphoton excess. Today's announcement makes all such papers into laughable jokes. Such papers are now like some paper claiming to find some deep significance in an arrangement of objects on a road, with someone later announcing that the objects ended up in such a way because they fell out of a passing truck at random intervals.

You can call it the Diphoton Fiasco. But such a fiasco only has lasted for about 8 months. A much larger fiasco is what we may call the SUSY Fiasco. This embarrassing physicist's debacle has been dragging on for 30 years. 

It's "OOPS" time for our physicists 

SUSY is a shorter name for the theory known as supersymmetry. The theory is an extremely complicated speculation. The Standard Model of physics has less than 30 independent parameters. But according to one scientific web site, supersymmetry has more than 100 independent parameters. According to another page at the same web site, more than 10,000 scientific papers “reference” the theory of supersymmetry.

With all that work by physicists, you would think that there must be some evidence for supersymmetry. But efforts to find evidence for the theory have been a complete failure. The Large Hadron Collider has completely failed to support the theory.

Why have physicists spent so much time on such a theory? It seems they were troubled by something called the hierarchy problem or the naturalness problem. The problem is hard to explain, but some excerpts from the Wikipedia article on the hierarchy problem may give you a little scent of it.

It appears that Fermi's constant is surprisingly large and is expected to be closer to Newton's constant, unless there is a delicate cancellation between the bare value of Fermi's constant and the quantum corrections to it. More technically, the question is why the Higgs boson is so much lighter than the Planck mass (or the grand unification energy, or a heavy neutrino mass scale): one would expect that the large quantum contributions to the square of the Higgs boson mass would inevitably make the mass huge, comparable to the scale at which new physics appears, unless there is an incredible fine-tuning cancellation between the quadratic radiative corrections and the bare mass.

The “incredible fine-tuning cancellation” being talked about here is a kind of matching of two unrelated numbers so that they end up canceling each other out – rather like what you might have if you had to pay on Friday a $5000 payment to save your house from foreclosure, and you coincidentally won $5000 in the lottery on Friday morning.

But it's actually much more of a coincidence. Because according to this scientific web site, “one has to hypothesize that the several correction terms cancel out to a part in 10^34 (a hundred billionths of a billionth of a billionth of a billionth), if one is to make the Higgs mass smaller than a lead brick.” So maybe our analogy should be that you own 6 houses that are each behind $5000 on the mortgage, with Friday being the last day for you to save them; and you coincidentally on Friday morning buy 6 different lottery tickets that each win $5000. That's the kind of fine-tuning that seems to be involved in the case of the Higgs mass.

Supersymmetry (also known as SUSY) is an attempt to offer an explanation for this fine-tuning, or to explain it away. But supersymmetry has always been a ridiculously ornate contrivance. For example, it imagines that almost every known type of particle has a corresponding “superpartner.” It would be quite the fantastic coincidence if nature was set up in such a way. So supersymmetry is basically a kind of gigantic case of “robbing Peter to pay Paul.” It tries to get rid of one fine-tuned coincidence (the hierarchy problem) by introducing a whole bunch of other fine-tuned coincidences, involving all these cases in which a known type of particle happens to have a matching “superpartner” particle.

Why do I use the term “the SUSY Fiasco”? It's because supersymmetry has been a gigantic waste of time. For years scientists were hoping that the Large Hadron Collider would produce some evidence for supersymmetry. But no evidence has been produced. The chance of supersymmetry being confirmed in our lifetimes now seems almost zero.

Below are some lessons we might learn from these blundering fiascoes. The first lesson is: avoid the hero-worship pitfall, and remember that physicists are just fallible humans like the rest of us. The second lesson is: remember that many of our scientists have an unfortunate tendency to “jump the gun” – they often get overexcited about some theoretical idea before there is good evidence for it. This tendency is abundantly evident in the field of biology as well as the field of physics. The third lesson is: when nature presents you with a dramatic case of apparent fine-tuning, don't waste tons of time twisting yourself into knots trying to explain it away. Just live with it. 

Postscript: Engaging in some morose commentary triggered by Friday's announcement, physicist Sabine Hossenfelder writes this (perhaps using hyperbole) at her blog Backreaction:  

During my professional career, all I have seen is failure. A failure of particle physicists to uncover a more powerful mathematical framework to improve upon the theories we already have...What worries me much more is our failure to learn from failure. Rather than trying something new, we’ve been trying the same thing over and over again, expecting different results. When I look at the data what I see is that our reliance on gauge-symmetry and the attempt at unification, the use of naturalness as guidance, and the trust in beauty and simplicity aren’t working. The cosmological constant isn’t natural. The Higgs mass isn’t natural. 

She refers to the cosmological constant, because it has the same type of fine-tuning problem as the Higgs mass (as discussed here).
 

Claims of Mouse Memory Manipulation by Optogenetics Are Unproven

Contrary to claims sometimes made, scientists have no solid evidence for any such thing as a memory trace (also called an engram), a physical change in a particular part of the brain that corresponds to the storage of a memory. How memory works is a great mystery. There are some scientists that have claimed to have learned or discovered something about memory traces or engrams, but such claims are not well founded. An engram is a hypothetical group of cells that might store a memory.

In 2013 we had an example of a very dubious scientific paper claiming to have found something relevant to this issue. Two scientists (Xu Liu and Steve Ramirez) claimed to have created a false memory in a mouse. Their paper was entitled “Inception of a false memory by optogenetic manipulation of a hippocampal memory engram.” Their claim was picked up by countless mainstream news sources, which failed to apply critical scrutiny to the very dubious claim. 

The experiment was done using some mice that were genetically engineered to be light sensitive.  An optical device was connected to part of their brains.  Mice were put into a box and given an electric shock. This, the scientists claimed, created a memory in part of the brains of the mice. 

Then later, when the mice were in a different room, light was transmitted over the optical device, into the brains of the mice. This, the scientists claimed, activated the memory that had been stored in the brain of the mice – supposedly because the mice “froze.” I may note that the use of the term “froze” and “freezing” in the study is kind of loaded terminology, a kind of non-objective “assuming what you are trying to prove” terminology. The correct objective way to describe a mouse that is not moving is to say the mouse was temporarily not moving. “Froze” is a loaded term specifically designed to get someone to think that a mouse stopped moving because of fear, but you can't tell how a mouse is feeling or what it is recalling merely by the fact that it stops moving.

We are told that this was an “implanted memory,” because the original memory was created not in the second box but the first box. This term is inaccurate. If an experiment like this were ever done in a convincing manner, the most it would demonstrate is an electronic activation of a memory. It is also inaccurate to describe the result as an inception or implant of a false memory (as their scientists did in their scientific paper). If I have a memory of being punched on Fifth Avenue, and then I recall or relive that memory while on Lexington Avenue, that is not a false memory. It is a true memory of something that happened in a different place.

A more serious objection to the research is that is did not provide convincing evidence of a memory activation or any type of unusual memory effect at all in the mice being studied. There are three reasons why I make this claim.

The first reason is that the number of mice tested was very small. When you read the paper, you will find the number of mice used was only about 6. That's way too small a sample size to be drawing any reliable conclusions. With a sample size that small, the results could easily have been due to coincidence. An experimenter wishing to show some particular effect could just keep trying until some round of experiments showed the desired effect. That would be hard to do with a large sample size, but easy to do with a very small sample size such as only 6 or 8 mice.

The second reason is that the conclusion about whether the memory was being remembered was presumably based on an observer judging whether a mouse froze, or stopped moving. The authors did not explain how it was determined that particular mice had “frozen,” and we can only assume that such a determination was reached from a subjective human judgment. Given the start-stop, helter-skelter way in which mice move, any judgment about whether a mouse froze is going to be a subjective judgment. So there is too much of a possibility of observational bias here, one in which an observer subjectively reports the effect he is hoping to find. Similarly, you might subjectively report that your goldfish in a goldfish bowl tends to move towards you when you are looking into the bowl, but that would probably tell us more about your desire to see something than about the goldfish.

The third reason is that the freezing effect could have been produced not by a recall of memories, but by the very fact that the energy was being transmitted into the brain of the mice. Imagine you are running along, and suddenly a scientist switches on some weird thing that causes some energy to pour into your brain. This all by itself might cause you to stop, even if it didn't cause you to recall some memory that caused you to stop. What could have been going on in the mice was just a kind of pausing effect caused by a novel stimulus rather than a recalled fear effect.

We have no idea what was going on in the minds of these mice. It is not sound to assume that a mouse is “frozen in fear” merely because it stops moving, or to assume that the mouse is remembering something when it stops moving. We have no way of knowing what mouse are remembering at any particular moments. We can also ask: why didn't the scientists try to use dissection to confirm their claim of a memory stored in some particular spot of the brain? The technique would be simple: train a mouse to fear some particular stimulus, then dissect some little part of the brain where you think the memory is stored, and see whether the mouse still fears the stimulus. 

A more recent paper by Ramirez and Liu was published in Nature, and was entitled, “Activating positive memory engrams suppresses depression-like behaviour.” But the paper shows the same type of methodological problems of their earlier paper. Figure 2 of the paper says that in one group there were only 6 mice used, and elsewhere the paper states that a control group had only 3 mice. These sizes are way below the 15 animals per study group (control and non-control) recommended for a reliable experimental result. The authors claim to have counted differences in the degree to which mice “struggled” when presented with a maze – again something involving a subjective interpretation in which a researcher might tend to see whatever he wants to see. The authors' interpretation of what is going on is speculative. The authors do not present any solid evidence that they actually activated a memory by optogenetic stimulation.

But to its credit, Nature did publish an article entitled “Brain-manipulation studies may produce spurious links to behaviour,” pointing out that shooting light into one part of a brain (the technique used by Ramirez and Liu) may cause other parts of the brain to fire off, resulting in unpredictable effects. “Manipulating brain circuits with light and drugs can cause ripple effects that could muddy experimental results,” the article cautions. That's another reason for doubting these mouse memory studies based on optogenetic brain stimulation, since it undermines the whole simplistic idea of “stimulate just this area and activate just this memory.”

The “mouse memory implant” research described above is inconsistent with a body of memory research produced over a much larger period of time: the memory research of

Karl Spencer Lashley. Over many years, Lashley did extensive research in which he tested how memory and learning is affected when you take out various parts of an animal's brain. In one extensive set of experiments, Lashley trained rats to run a maze. The rats then had parts of their brains removed. Lashley found the rats were able to run the maze just as well regardless of which part of the brain was removed. Strongly indicating that particular memories are not localized in one particular part of the brain, this research directly contradicts the “mouse memory implant” work that tried to suggest that a memory was stored in one particular part of the brain.

Lashley tested using three types of mazes of varying difficulty. Astonishingly, Lashley found that you could remove half of a rat's brain, and it had very little effect on the rats ability to remember either of the two simpler types of mazes.

Here are some startling results listed by Lashley (and discussed here):

1. Rats, trained to have a differential reaction to light, showed no reduction in accuracy of performance when the entire motor cortex of the brain, along with the frontal poles of the brain, was removed.
2. Monkeys were trained to open various latch boxes. The entire motor areas of the monkeys' brains were removed. After 8 to 12 weeks of paralysis, during which they had no access to the latch boxes, the monkeys were then able to open the boxes “promptly” and “without random exploratory movements.”
3. Rats were trained to solve mazes, and the rats then had incisions made separating different parts of their brains. This produced no effect in memory retention.
4. Monkeys were trained to unlatch latch boxes. After having their prefrontal cortex removed, there was “perfect retention of the manipulative habits.”
5. “A number of experiments with rats have shown that habits of visual discrimination survive the destruction of any part of the cerebral cortex except the primary visual projection area.”

After discussing these and many other experiments he did for many years, Lashley said this about the idea of an engram or memory trace: “It is not possible to demonstrate the isolated localization of a memory trace anywhere within the nervous system.”

Lashley's research is completely inconsistent with the research claim of Ramirez and Liu. Lashley's research provides compelling evidence that particular memories are not stored in particular parts of a brain. Conducted over more than 30 years with a huge number of animals, Lashley's research was many times more extensive than the scanty 6-mouse research of Ramirez and Liu that got so much press coverage. Given a conflict between the two lines of research, we should believe Lashley's research, which is so much more voluminous. Contrary to the claims of some optogenetic researchers using dubious methodology, there is no compelling evidence that particular memories are stored in particular parts of the brain, and no convincing evidence that specific memories can be recreated by stimulating particular parts of the brain. There is no good evidence for any such thing as a memory engram, a particular set of cells that stores a particular memory. Lashley's many years of research strongly indicates that such ideas are not valid, as does the research of John Lorber (who, as described here,  documented many cases of humans who functioned very well, despite having most of their brains destroyed through disease). 

Postscript: In 2014 our credulous and exaggeration-prone news media reported that researchers Wiltgen and Tanaka had erased specific memories in a mouse. But the reports were based on a research paper that justified no such conclusions.  The paper states in its Figure 2 that only 6 mice were used for a study group, and 6 mice for the control group. This is way below the standard of 15 animals per study group (control and non-control) needed for a reliable experimental result. The same problem is shown in Figure 3 and Figure 4 of the paper. The paper reported borderline results, bordering on statistical insignificance.  It gave no clear evidence of having erased any memory in a mouse.  The paper had some of the same methodological problems as discussed above, such as relying on judgments of a mouse's "freezing rate" that is very hard to objectively quantify. 

Post-Postscript: The latest example of a memory experiment failing to actually prove anything (because of its too-small-sample size) is a study in Nature that has been hyped with headlines such as "Artificial memory created."  The study has the inaccurate title, "Memory formation in the absence of experience." The study fails to prove any such thing occurred. When we look at the number of animals involved, we often find that the study fails to meet the minimum standard of 15 animals per study group.  In Figure 1 we learn that two of the study groups consisted of only 8 mice. In Figure 2 we learn that two of the study groups consisted of only 10 mice.  In Figure 3 we learn that one of the study groups consisted of only 7 mice.  Moreover, the methodology used in the study is so convoluted that it fails to provide clear and convincing evidence for anything interesting.  The only evidence of memory recall is that the mice supposedly avoided some area,  something that might have occurred for any number of reasons other than a recall of some memory.  A robust test of an artificial memory would test an actual acquired skill, such as the ability to navigate a maze in a certain time.