Posted by PZ Myers
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 thatpsychological 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’syou. 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.
