Michael Egnor, neurosurgeon, has made a bizarre post in which he reveals that he knows nothing about how the brains he cuts up work. Egnor claims that it is impossible for the brain to store memories. Yes, he knows that neural damage can cause loss of memory, that certain delicate areas of the brain, if harmed, can destroy the ability to make new memories, and he waves those awkward facts away to announce that there is simply no way memory or information of any kind can be stored in a meat-organ like a brain. He doesn’t say where memories are kept, then, nor does he account for any of the physiological correlates of memory, nor does he seem to give a damn about any of the neuroscience experiments that have teased apart the underlying molecular mechanism. By pure reason alone, if we can call his argument a product of reason at all, he deduces that the brain could not possibly have any way of storing memories.

His first argument is by cock-eyed definition.

It’s helpful to begin by considering what memory is — memory is retained knowledge. Knowledge is the set of true propositions. Note that neither memory nor knowledge nor propositions are inherently physical. They are psychological entities, not physical things. Certainly memories aren’t little packets of protein or lipid stuffed into a handy gyrus, ready for retrieval when needed for the math quiz.

The brain is a physical thing. A memory is a psychological thing. A psychological thing obviously can’t be “stored” in the same way a physical thing can. It’s not clear how the term “store” could even apply to a psychological thing.

So his first argument consists of defining memory as a certain category of thing, and then asserting that that particular category is obviously incapable of being represented in a physical matrix. How does he know this? It suits his thesis, so he simply insists on it.

But if memory is patterned activity in the brain, then of course that pattern can have a physical cause: the spatial arrangement of axons and dendrites, the localization of proteins at synapses, subtle changes in synaptic boutons that modify their electrical properties.

For example, Eric Kandel won a Nobel (with Carlsson and Greengard) in 2000 for figuring out how memories are stored in Aplysia.

Eric Kandel, Center for Neurobiology and Behavior, Columbia University, New York, is rewarded for his discoveries of how the efficiency of synapses can be modified, and which molecular mechanisms that take part. With the nervous system of a sea slug as experimental model he has demonstrated how changes of synaptic function are central for learning and memory. Protein phosphorylation in synapses plays an important role for the generation of a form of short term memory. For the development of a long term memory a change in protein synthesis is also required, which can lead to alterations in shape and function of the synapse.

Aplysia can learn to associate a touch with an unpleasant stimulus, and will remember that association when touched in the future, which is a psychological thing. We know how that psychological thing is stored in the brain of Aplysia, as changes in the strength of synapses. Egnor is therefore refuted on his first claim.

His second argument has to be seen to be believed. Here he is talking about a memory of your grandmother, and how you recall it.

As you try to remember Nana’s face, you must then locate the engram of the memory, which of course requires that you (unconsciously) must remember where in your brain Nana’s face engram is stored — was it the superior temporal gyrus or the middle temporal gyrus? Was it the left temporal lobe or the right temporal lobe? So this retrieval of the Nana memory via the engram requires another memory (call it the “Nana engram location memory”), which must itself be encoded somewhere in your brain. To access the memory for the location of the engram of Nana, you must access a memory for the engram for the location for the engram of Nana. And obviously you must first remember the location of the Nana engram location memory, which presupposes another engram whose location must be remembered. Ad infinitum.

He lapses immediately into dualist assumptions. There is a separate you from your brain, which has to go searching through the brain like a garbage picker rummaging through the rubbish bins to find that portrait of Nana. But that’s clearly not how it works. There is no external entity that has to trace through a series of memory locations — memory is a set of invoked associations. It’s you. There isn’t a homonculus somewhere rifling through the stacks of memories, but instead, those memories are part of the youness of you, and triggering that pattern of activity is part of the consciousness being expressed by your brain…that is, your mind.

This imaginary engram search story only makes sense if you assume dualism and that memory is co-dependent on finding a memory in a disorganized heap, and as Egnor points out, it doesn’t work. By his own reasoning, his model fails.

It’s bizarre that a neurosurgeon would have such medieval ideas about how the brain works, while simultaneously being aware that making a mistake with the organ under his knife can directly affect memory, behavior, personality, and health. But then, neurosurgeon does not mean neuroscientist, as he clearly demonstrates.

I suspect that these silly ideas of his are a product of a fear of mortality. If the mind is a product of the brain, when the brain dies, the mind dies, too; there is no afterlife. As a surgeon who probably deals with patients with serious deficits in their brain caused by stroke or disease, the dependency of self-identity on the physical structure of the brain has to be made glaringly obvious to him with depressing regularity, so he has developed this myth to cope. There must be a Magical Spiritual Essence that is working through the meat in your head to produce you, so even when disaster reduces a person to having the cognitive capacity of a carrot, it just means the Magical Spiritual Essence is blocked from pulling the strings on your corporeal puppet…but have no fear, it’s still there, and when it finally gives up on your flesh it’ll be able to flit up to Heaven and join Nana and Sparky, your childhood puppy, and all will be well.


  1. #1 Harvey
    December 15, 2014

    Although I agree with you that he has made several ridiculous assumptions which neither he nor science can support with scientific evidence, I am afraid that you have promulgated several assumptions as to his motives and behavior that are no better supported. Is there any evidence that he is 1) a believer 2) afraid of the “hereafter” and/or 3) in any way insincere in the theory he has proposed?

  2. #2 PZ Myers
    December 15, 2014

    1) He is a confessed believer, 2) he’s not afraid of the hereafter because he has a lovely rationalization to say it will happen (more likely he’s afraid of oblivion), and 3) nowhere do I say he’s insincere. He’s just stupid and wrong.

  3. #3 AnswersInGenitals
    December 15, 2014

    Doesn’t his homonculus, his “youness” require a deeper homonculus to tell homonculus#1 where to look? That’s Egnor’s Ad infinitum. It’s turtles all the way down again (or all the way up since heaven must be ass deep in homonculi, homonculae, whatevers).

  4. […] Source: Ready to lose a few brain cells? You won’t need them, apparently [Pharyngula] […]

  5. #6 Surdas
    Gatineau, Canada
    December 15, 2014

    I guess he hasn’t heard of a computer hard disk, which is able to store information on a solid medium and then retrieve it.

  6. #7 Brad
    December 15, 2014

    A few random points….

    (1) He’s not a dualist. Suggesting different dimensions of human experience isn’t dualism. He’s under no obligation to justify a “humonculus” or whatever fire you want to hold him to for your failure to think in any detail about non-materialist paradigms for explaining human experience. Ever heard of Wittgenstein? Was he “stupid”? Or is the non-materialist history of human thought stupid? What about sociologists, who begin with soft science paradigms? Are they stupid, too? I know little about you, but I know you like to dish out “stupid” and “dumb” a lot. I would love to see your canonization of stupids. And if this guy’s a dualist, quantum physicists, astrophysicists, and any physicist who recognizes that models of explanation undergo revisions and revolutions every few decades are all stupid dualists.

    (2) Dualism isn’t a medieval idea. It’s a Cartesian one (e.g. a modern one). It was used as a justification for epistemic foundations of the modern sciences. It failed, and so did physical reductionism that tried to take its place. You just haven’t read enough history of human thought to know your drivel has been attempted century after century, and fails century after century.

    (3) I wonder what gives you, a BIOLOGIST, anymore god-like qualification to suggest this neurosurgeon has no authority to talk about neuroscience (as if neuroscience was a hard science, anyway).

  7. #8 Ben
    Melbourne, Australia
    December 16, 2014

    His definition of memory is incomplete. Memory is not just “retained knowledge.” It variously consists of episodes, knowledge, and skills. These forms of memory are not completely independent, but they can be affected in different ways by brain damage. Bilateral insult to the medial temporal lobe, for example, tends to affect episodic memory much more than procedural skill learning.

    There is an abundance of literature describing how memory works in the brain, from the synaptic level to gross anatomy, and the literature continues to grow as new technologies (e.g., fMRI, MEG, etc) are applied to enduring questions. Astoundingly, this neurosurgeon appears to be either ignorant of that literature or otherwise deliberately ignores it.

  8. #9 Gralgrathor
    December 16, 2014


    He’s not a dualist

    Hm. Isn’t he saying that the physical structure of the brain can’t record memories, and that there must therefore be a non-physical component to the mind? Do you suggest that he believes mind is part physical, part non-physical? Wouldn’t that also be called dualism?

    is the non-materialist history of human thought stupid?

    One can have an opinion about that.

    as if neuroscience was a hard science

    Neuroscience is the scientific study of the nervous system, a physical structure, subject to physical laws. How could it be anything but a ‘hard science’?

  9. #10 Ulf Lorenz
    December 16, 2014

    To show what nonsense he purports, it is sufficient to consider the first excerpt only.

    1. He defines knowledge as “the set of true propositions”, which is questionable at least (what about “obviously wrong” knowledge?).

    2. He asserts that memory, and even knowledge are “[…]psychological things, not physical entities”, and suggests that they cannot be stored physically. This argument is absurd, as can be shown by the mere existence of books (those containing “knowledge”).

    He can probably overcome these problems with enough redefinition, but the connection to reality will probably suffer.

  10. #11 Fernando
    December 17, 2014

    @Brad: If you think dualism is a Cartesian idea then you haven’t read enough history of human thought yourself.

  11. #12 Howard Brazee
    United States
    December 17, 2014

    I’d be very afraid of the hereafter if I believed my memories/soul would last forever no matter what I desire. And forever makes a million years look like an instant.

    It’s interesting that so few people have come up with a version of Heaven that is attractive. It seems that lots of people are more concerned that Hell exists to punish wrong-thinkers.

  12. #13 Alonso Riestra
    December 18, 2014

    Egnor thinking is based on the mistaken idea that memories in our brains are locally stored instead of distributedly represented. If our memories were locally stored, we would certainly need a mechanism to find where they are. This is why we have page numbers and indexes in books, alphabetical coding in dictionaries and digital addresses in computers. As a matter of fact when we erase a file in a digital computer what we erase is its address, making its location available for other information to be stored. However, in contrast to other systems of storage and retrieval of information, our memories are encoded in a distributed fashion within a network. “Content addressable memory” is a very important feature that arises from this kind of encoding, meaning that any feature of the memory may activate its whole representation. To me this is the most important argument. Egnor (and some others in this chat) fully ignore the concepts of content versus locally addressable memory and believe that a memory is something that you pull out from a drawer instead of a pattern of activation of a neuronal network. But, at any rate, and with all due respect, I missed the part where a neurosurgeon became and expert in cognitive psychology, and by the same token, from Aristotle to Wittgenstein, rivers of ink have been spilled about human nature but philosophers knew close to nothing about the workings of the human brain. Not a single experiment, not a whiff of empirical reasoning, as with Egnor, everything is only in their heads.

  13. #14 Sheogorath
    New Sheoth, The Shivering Isles
    December 22, 2014

    Allow me to disprove this crazy hypothesis by a simple rephrasing of it: An SD card is a physical thing. A datum is an intangible thing. An intangible thing obviously can’t be “stored” in the same way a physical thing can. It’s not clear how the term “store” could even apply to an intangible thing.
    Yet SD cards clearly store all types of information as digital data, amirite?

  14. #15 mark
    December 27, 2014

    I used to keep my memories in my brain, but now I use The Cloud.

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