Myths about how the brain works
nautil.us
nautil.us
Edit for clarification: I was not expecting folks to respond to this by linking split-brain experiments; I am specifically referring to split-brain experiments showing us that our ideas about left brain/right brain were correct. This was in reply to "I'd agree with this author that they are oversimplified and generally incorrect - I'd add the left brain right brain divide to the list" -- I want to know what this person thinks, thanks.
> McGilchrist digests study after study, replacing the popular and superficial notion of the hemispheres as respectively logical and creative in nature with the idea that they pay attention in fundamentally different ways, the left being detail-oriented, the right being whole-oriented.
[1] https://en.wikipedia.org/wiki/The_Master_and_His_Emissary
Each time I lose feeling in right side of body, and lose the ability to write. Not 100%, but close enough. Typing is fine however, if slow. Critical thinking goes to crap. Talking is fine. I can still draw, though my motivation goes to crap.
Is weird what stays and what goes.
Last time I looked writing is a left brain activity. Which controls right side.
I can read and speak well enough. Thinking is harder, so I tend to stay quiet.
However, there's left-brain/right-brain in terms of "some functions of the brain tend to be more on one side or another", and then there's left-brain/right-brain in terms of a pseudoscientific personality test about whether you're more of a "logical" thinker or "artistic" thinker, blah blah blah. There's no evidence for that. It's just mumbo-jumbo Buzzfeed-style quizzes to make you feel good about yourself.
The brain is complex.
Edit: https://en.wikipedia.org/wiki/Agenesis_of_the_corpus_callosu...
> So why does the myth of a compartmentalized brain persist? One reason is that brain-scanning studies are expensive. As a compromise, typical studies include only enough scanning to show the strongest, most robust brain activity. These underpowered studies produce pretty pictures that appear to show little islands of activity in a calm-looking brain. But they miss plenty of other, less robust activity that may still be psychologically and biologically meaningful. In contrast, when studies are run with enough power, they show activity in the majority of the brain.
Another, more relevant reason, is that brain-scanning studies are in their infancy.
It’s expensive to run brain scanning studies, so studies have smaller populations or lower resolution data collection in response. Yes, brain scanning studies are new, but we’ve been doing fMRI studies for nearly 3 decades and it’s still expensive. Had that cost been scaled back, we’d have more and/or better data because grants are (very) finite.
As such it’s impossible to say what subset of brain activity is directly related to some activity rather than some related mental processes.
There's a lot of signal processing theory, regression analysis, etc. that goes in to it. With that said, the issue that arises is that only the strongest correlates may surface or be observed. There may be a lot of brain activity that overlaps or looks identical between that resting state (baseline) and the stimulation state, but can't really be included because a distinction can't be made, which goes back to your final point. That, however, doesn't mean that there aren't actual subsets of brain activity that we can attribute to a specific activity.
For example, if you're in an fMRI and I show you nothing but a fixation cross, then show you a sad image at a specific time for a specific interval, then went back to the fixation cross, and also showed you a scrambled version of that same image, I can (oversimplified) run a diff check to see what's different between the three. From there, I can remove the overlap between the three from normal baseline activity and activity specifically related to visual processing (scrambled image) to reveal what's specifically different with that sad image. If I see that the amygdala has much higher activity during that sad image compared to the fixation cross and the scrambled image, I can conclude that it has some role in emotional processing (well not really in this example because you'd also need a ton of images, including neutral images, with different orderings of each to really be confident; also really couldn't make that conclusion, just present the correlation because...science).
The point is that there are methods to isolate activity related to a specific activity/stimuli/response/etc. However, it's currently very difficult, if not impossible, to make distinctions in those overlapped areas.
Note: this is obviously an oversimplification of neuroimaging research and analysis
The simplest thing you can do in a scanner is have them sit there doing nothing while you acquire scans. In the end, you just have a 4d matrix of unsigned integers. For each voxel you can acquire an average over the scan and check whether it is significantly above zero using a t-test. Given enough data everything will be significantly greater than zero, including parts outside the head. Or you can compute a global mean to center all the voxles, and check which parts of the brain are significantly above the average, or significantly below the average. Extremely simple analyses (and so yes, there are lots more you could do).
In task fMRI, you have them do a task, and you use events in your task design as predictors of the BOLD, and then display a voxel map of either the beta values, or, more commonly, the T-values of those regression betas (or a contrast of those regression betas). In this case, you really aren't looking at activity. You are looking at correlations.
Those islands of activity in whole-brain analysis images in figures in papers happen because the result images are thresholded, e.g. at p < .05 false-discovery-rate correction for multiple comparisons. Personally, I think unthresholded images are better because they are more informative.
Let's take a concrete example. You have a subject do a task where they have to choose between two gambles varying in risk and reward. Then, for each voxel, you predict the BOLD time course using a series of events (time of presentation of gamble options) with magnitude equal to the coefficient of variation between the two gambles. So now, for each voxel you have a beta value showing how CoV predicts BOLD. You notice that anterior insula on both cases has the highest beta values. You threshold at conventional statistical signficance, after correcting for multiple comparions, and all the spurious, or less important, correlations drop out of the image, and you are left with two bright spots on a map pin-pointed on the left and right anterior insula. See: in this anaylysis, not all "psychologically and biolotically meaninful activity" is being examined or looked at. For example, button presses events show up localized in the motor areas too, but they weren't looking at those. But they could have, if we were interested.
https://en.wikipedia.org/wiki/Wernicke%27s_area https://en.wikipedia.org/wiki/Broca%27s_area
The evidence for more advanced brains in higher mammals is also plainly there.
The author seems to be over-stating all this stuff in order to reject it.
They may be bad abstractions at a lower level of detail, but for general purposes they seem to be useful enough.
Solutions offered based on bad simple metaphorical models have the benefit of being intuitive, so they stick around.
Theory-theory is the Efficient Market Hypothesis applied to common sense.
Interesting that you had this takeaway, I didn’t get a sense of this at all. My takeaway was that the author presented modern findings (which constitute our present model for how the brain works, speaking nothing to a notion of some absolute correctness) to dispel older hypotheses that are disprovable based on the latest research. As presented, IMO, the author captures well that these modern findings are just a reference point against which to refute the stubborn tropes.
The mirror neuron system is also a myth-myth. While there aren't "mirror neurons", per se (e.g., biochemically different), there is a system of mirroring and it is very important
Speaking specifically to left vs right brain, in popular media I've mostly seen it presented as logic vs creativity, which completely disregards that people can be creative verbally, and that certain quantitative/technical things are very non-verbal.
Lithium is a great example - very effective treatment for bipolar. No one really knows why. Prescribed for decades as they've tried to figure it out because tests showed it was effective and relatively safe, just no one knew exactly what it was doing in there.
It's sort of how you can be a woodworker without knowing the cellular biology of trees, and without being an electrical or mechanical engineer who can build a table saw from scratch.
Lithium-rich mineral springs have historically been touted for their healing properties. It was first used for mania in the late 1800s, with Denmark leading the way, but little was published about the medication for more than half a century.
https://www.verywellmind.com/lithium-the-first-mood-stabiliz...
I'm a believer in modern scientific medicine, but think we often have it backwards. Before reinventing the wheel we should exhaustively test what we used traditionally. Maybe the reason we don't do much of that is that it's not possible to patent, and so there's no financial incentive to do so?
https://pubmed.ncbi.nlm.nih.gov/?linkname=pubmed_pubmed&from...
It also doesn't make its way into mainstream practice among GPs and psychiatrists. As an example, which mainstream practitioner would ever prescribe or recommend curcurmin with piperine for any condition, aside from alternative medicine practitioners? Which psychiatrist would recommend EPA fish oil for depression? I could go on. The research that does exist is largely ignored.
Also, the many dead ends thing is true in general for pharma, but at some point there are too many dead ends for it to be profitable even given their bankroll. This is happening a lot lately with neuro-related drug development. In the last 10 years I know Amgen, Pfizer, Novartis, Eli Lilly have all had shut downs/lay offs in their neuroscience research divisions.
Subtle, but I get it :D
Link for those curious about this comment:
(Neural Correlates of Interspecies Perspective Taking in the Post-Mortem Atlantic Salmon: An Argument For Proper Multiple Comparisons Correction)[https://teenspecies.github.io/pdfs/NeuralCorrelates.pdf]
We tend to give the impression that we’ve figured almost everything out, and so you’re just learning the facts of it all.
Really, we’ve carved out a little island in a sea of ignorance, and the foundations of the island are just our current best rough approximations that might collapse.
An example from the field I’m in — biology. It’s quite likely that if you worked at it you can describe a new species in your backyard. You don’t have to go to the Amazon rainforest, there’s scientific unknowns all around you all the time.
We also have some grand principles that further unite the field, like the cell as the basic unit of organismal life, emergent properties of higher order systems, &c.
The remaining work is mostly 'stamp collecting' - looking at the details of the output of that algorithm. Of course those details are enormously complex. Kind of like mapping out the Mandlebrot Set after you already know the algorithm.
If you wanna cure cancer, resolve chronic diseases, conserve ecosystems under climate change, etc.
It’s cool to know that DNA exists and that life evolves by natural selection, but getting into the complex weeds of that fractal is where we discover that we know so little.
There is plenty, more than enough, data to work with, and many promising/proven models to build upon, need more good theorists in the field.
Saying "but we don't know much" is just being lazy.
This is where science communication fails, the general population and even the most curious people still think that there is such a thing as "Jennifer Aniston neuron", but in reality there is "Rachel from Friends neuron" that sits at the top of hierarchy where the signalling converges and then it's highly likely it isn't the only thing it's responsible for (OR gate), but finding what is the hard question. This is speculation stated at about 20min in this talk: https://www.youtube.com/watch?v=Y1ID0FQN9tg
Also, a small nit about the way it was presented was using plasticity (i.e. areas area able to perform different kinds of processing if the inputs change, e.g. blindfold + braille) as evidence of non-specialisation. That's doesn't follow. Just because neurons can be flexible doesn't mean they're not performing a discrete task, although I agree with the general conclusion.
A small nit about your small nit: The article does not make that claim. Quote:
> I’m not saying that every neuron can do everything, but most neurons do more than one thing.
I mean, it's kind of obvious that all neurons are far from completely interchangeable, like RAM cells on a memory chip, since there clearly is quite a bit of higher level architecture.
This is also what Freud meant by "time doesn't exist in the unconscious". What we call memory isn't discrete like RAM, nor is it organized around what we perceive as time, these are illusions of how we experience perception and consciousness. He described by suggesting we imagine the modern city of Rome, then, directly physically overlay ancient Rome on top of modern Rome, physics be damned, if an ancient column goes through a modern building, then it goes through the modern building without destroying it, directly occupying the same space at the, er, same time
I would like to add one more myth the list. The idea that we all have a finite amount of brains cells.
They used to teach that we’re all born with a certain amount of brain cells, and over time from aging, or getting a concussion, or if you ‘do drugs’, you would lose said cells. And that’s that. No more new brain cells :)
We know this to be false now. I don’t know how much this one has persisted, I haven’t heard it in a while. But it was drilled into my head as a kid.
Not related to brains, but another health myth that comes to mind is the idea that our tounges & taste buds are divided into ‘zones’ that perceive the different flavors. I don’t remember the order, but something like the tip tastes sweet, the middle is umami, the sides are sour, et cetera.
Now we understand all taste buds taste all flavors. Is is interesting these old models science came up with to try to explain things, and how long some of them persisted.
PS: Check out the 2002 album ‘Phrenology’ by the Roots. It’s a classic!
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4306487/
From the introduction: ”For a long time, it was thought that the nervous system is fixed and incapable of regeneration. Although it is indeed true that most neurons in the brain are generated before birth and are never exchanged, it is now well established that new neurons are continuously generated by stem cells in at least two discrete regions in the brain throughout life in most mammals: the hippocampus—a seahorse-shaped structure underneath the cortex that is important for memory formation and cognitive functions; and the olfactory bulb (OB)—a structure located above the nasal cavity that is important for the sense of smell.”
“Tongue map” -> https://www.livescience.com/7113-tongue-map-tasteless-myth-d...
To be honest, after reading a little more, I’m a little unclear on if ‘all taste buds taste all flavors’. I might be wrong to say it like that. I saw one thing that said there are actually different types of receptor cells, but they are not isolated into zones, and somewhat evenly distributed across the whole tongue.
The older parts have evolved to specific functions, while neocortex, which is found in mammals, has a uniform structure and is capable of learning and adapting to different tasks. 75% of human brain is neocortex.
Jeff Hawkings explains the difference between the 'old parts' and 'new parts' pretty well in this interview: https://www.youtube.com/watch?v=-EVqrDlAqYo&t=366s
Panksepp, J. (2007). Neurologizing the Psychology of Affects: How Appraisal-Based Constructivism and Basic Emotion Theory Can Coexist. Perspectives on Psychological Science, 2(3), 281–296. https://doi.org/10.1111/j.1745-6916.2007.00045.x
Panksepp, J. (2008). Cognitive Conceptualism—Where Have All the Affects Gone? Additional Corrections for Barrett et al. (2007). Perspectives on Psychological Science, 3(4), 305–308. https://doi.org/10.1111/j.1745-6924.2008.00081.xWhile that data shows that brain functions aren't strictly fixed and neuroplasticity is a thing, it does show that locations in the brain do have disproportionate impact on certain functions.
https://calteches.library.caltech.edu/1575/1/Science.pdf
“For instance, the scientific article may say, 'The radioactive phosphorus content of the cerebrum of the rat decreases to one- half in a period of two weeks.' Now what does that mean? It means that phosphorus that is in the brain of a rat—and also in mine, and yours—is not the same phosphorus as it was two weeks ago. It means the atoms that are in the brain are being replaced: the ones that were there before have gone away. So what is this mind of ours: what are these atoms with consciousness? Last week's potatoes! They now can remember what was going on in my mind a year ago—a mind which has long ago been replaced. To note that the thing I call my individuality is only a pattern or dance, that is what it means when one discovers how long it takes for the atoms of the brain to be replaced by other atoms. The atoms come into my brain, dance a dance, and then go out—there are always new atoms, but always doing the same dance, remembering what the dance was yesterday.”
> Depression is usually catalogued as a mental illness, but it’s as much a metabolic illness as cardiovascular disease, which itself has significant mood-related symptoms. These two diseases occur together so often that some medical researchers believe that one may cause the other. That perspective is steeped in Cartesian dualism. Both depression and cardiovascular disease are known to involve problems with metabolism, so it’s equally plausible that they share an underlying cause.
What working out does definitely improve is my sex drive and self-esteem, so it's important to know what's the triggers for your depression, as it may help anyway.
Myth #1: Brain areas aren't separate and didn't evolve in stages.
1. Brain (neocortex) areas aren't single-purpose. Obviously neuroplasticity is a thing, but the article ignores that areas of the brain develop to be focused on a single category of tasks (visual, auditory, etc.). The author's example, blindfolding someone and watching their visual cortex get repurposed when learning to read braille, ignores that if you don't blindfold them, other areas will probably take up most of the task of learning braille because it's not a visual activity and the brain tends to separate areas of responsibility.
2. The number of significant evolutionary steps may not be just three, so the triune brain theory may be technically false, but I've never seen any actual neuroscientist argue that it isn't roughly accurate. The evidence in the article is molecular genetics: the fact that there aren't radically different kinds of neurons. This is like scaling up an argument that ethanol and glucose are the same thing because they share the same elements. If the limbic system and neocortex have roughly the same kind of neurons, what does that matter? We know they serve radically different purposes, and we know that reptiles don't have a neocortex (at least, nothing of significance).
Myth #2: Brain is stimulus/response machine
Her argument against this myth seems tortured. Of course the brain is not a simple impulse/response machine, but it's still essentially taking in inputs and responding in various ways. It just has a mind-bogglingly complex internal state.
Myth #3: Strong dividing line between diseases of the brain and body
Everything seems to point to her being right on this one. Science knows, nearly as much as it can know anything, that neurological stress leads to physical stress responses which can screw up other parts of the body, often through hormone dysregulation. Similarly, physical problems from gut health to inflammation can trigger immune responses or simpler biochemical reactions that have neurological side-effects. And, of course, diet. Psychoactive drugs are a clear example of how an external physical influence can have psychological effects.
> Myth #3: Strong dividing line between diseases of the brain and body
> Everything seems to point to her being right on this one.
The problem is that most of the time people debunk this "myth" they are using some motte-and-bailey tricks.
First, there is no perfect dividing line between disease of the brain and body, but there is also no perfect dividing line between diseases of the brain and differences of the brain (do domestic abusers have bad character or a disease?) or between diseases of different organs. Nevertheless, it is highly useful to have a taxonomy of phenomena that cuts reality roughly at its joints. These divisions have important practical and moral implications, and they fact that there are gray areas does not mean the categories should be undermined.
Second, these seemingly scientific "there is no line" arguments are almost always used asymmetrically by experts to advance a normative position, e.g., my psychological disease should be treated like a physiological disease by the law and my friends because there is no perfect distinction between the psychological and physical. It is possible to go in the other direction and argue that many/most alleged psychological diseases are really just different preferences and should be treated as such; see Thomas Szasz:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5353517/
This is just as well supported by "there is no line" argument as folks who want physiological-psychological disease equality. The reason the latter position is more popularly is based on values.
The author was dispelling the myth that a significant fraction (or all) of neural activity happens between the time of the stimulus and time of the response, which is probably a common misperception.
If that is the case, then I do think the author has made a slight blunder because the audience who would read their article is unlikely to include significant portions of people who would've lacked the exposure needed to have that much stricter and more incorrect mental model, and thus the author could've done better to present the myth so as to not confuse it with the not as incorrect mental model of the brain that their likely readers have.
from Wikipedia: "For Fodor, significant parts of the mind, such as perceptual and linguistic processes, are structured in terms of modules, or "organs", which he defines by their causal and functional roles. These modules are relatively independent of each other and of the "central processing" part of the mind, which has a more global and less "domain specific" character. Fodor suggests that the character of these modules permits the possibility of causal relations with external objects. This, in turn, makes it possible for mental states to have contents that are about things in the world. The central processing part, on the other hand, takes care of the logical relations between the various contents and inputs and outputs"
> Brains don’t work by stimulus and response.
They definitely do, eg. when you accidentaly touch a hot object. But that's not all they do. They also have a predicting mode of operation.
> specific parts of the human brain have specific psychological jobs
There are parts of the brain doing specialized things, otherwise why do we still call an area of the brain "visual cortex"? But the brain is much more malleable and plastic than we thought earlier, and entire areas can be repurposed.
The author makes too much about parts of the brain not being specialized.
As a neurosurgery resident in a former life who actually operated on brains and took care of people with strokes and trauma, yes, different parts of the brain are specialized to do different things. Yes, there is plasticity, but there are limits to it, especially once you reach adulthood.
I will give some anecdotes, but these are very, very typical.
Example, frontal lobe and impulse control. Saw an older patient with a giant tumor in the frontal lobe. His family came with him. Seeing where the tumor was, I asked the family if they had noticed any recent decline in his impulse control. Their response: "Now that you mention it,..." and out came all sorts of stories how their previously very proper father, was now doing all sorts of very things with very poor judgement and had even gotten in trouble with the law. If your frontal lobes get damaged, you will have issues with impulse control, long term planning, etc.
Another example is speech. Speech is very localized to areas of the left brain. As an example, there was patient with seizures in the left brain so bad that we would have to remove parts of the brain to control them. We did a surgery where we opened up the skull, and then woke the patient up. Psychologists asked the patient to do various verbal tasks, while we touched different parts of the brain with an electrode. When the electrode touched the parts of the brain that control speech, the effect was instantaneous, the patient suddenly stopped talking mid-word. By doing this, were were able to map precisely which parts were being used for speech, and in the surgery, avoid those areas. The patient had a very good outcome with his seizures stopped, and still able to speak.
Another example is movement disorders. Worked with a surgeon who is a world class expert in deep brain stimulation. In there you precisely place an electrode into a specific part of the brain and turn it on. Once you do that, you can have someone with severe tremor or Parkinson's who has been unable to even write their name for years, suddenly are able to write. You turn off the electrode, and the effect goes away. If the electrode is off by a millimeter, it does not work. It has to be precisely positioned.
In terms of mental illness, I have seen patients with severe depression and obsessive, compulsive disorder improve significantly after precise placement of an electrode in the correct part of the brain.
This thing about parts of the brain specializing is not just abstract theory. It is used every day by neurosurgeons, neurologists, etc to make life and death decisions. It has a lot of real world evidence backing it up. The most important question to answer when you see someone with a stroke or brain trauma, is "where is it located?" The same size injury can have vastly different effects on the person depending on where it is.
I’m firmly in the zone of “I don’t know what I don’t know” when it comes to neuroscience but the hard emphasis on the areas of the brain not being specialised was in stark contrast to literally everything I’ve read about the brain and neuroscience to date.
I wonder if the author is pushing both sides of the coin of “myth” and “reality” way to far to the extremes.
I agree with another commenter that perhaps the author is trying to push back against older, more rigid ideas of much more extreme separation of functions of the brain in a more primitive sense.
But some detail is lost here, because as far as I’m concerned (and I’m heartened by the support that your more experienced and expertise-led comment provides) the brain absolutely and demonstrably has specialised areas that focus on certain functions.
So in an effort to bust these “myths” I feel parts of this article just serve to muddy the water and add some confusion rather than clarity.
By way of analogy, you can disable a car sooner or later by breaking the ignition switch or the gas tank lid. But those points are not alone responsible for the transportation function of the car.
The wheels of the car are involved with and vital for acceleration, steering, and braking. Without transmission and suspension, wheels do none of this.
The transmission of the car is capable of both propulsion and braking.
To think of speech as a function of a small part of the left side of the brain is incomplete. Speech requires a number of motor, sensory, respiratory and data systems to work together in a coordinated pipeline that exists across the whole brain and body. The neurons involved in those circuits also work to perform other functions.
All my sites looked terrible until I learned to paint.
Is this a polling system...
Oh actually more like a branch predicting system...
These are the first two sentences of the article and already I'm skeptical. I'd say the self-driving cars are mostly a product of recent technical inventions and not scientific discovery - the scientific discovery happened mostly in the XX century, with discoveries which made integrated circuits, or lasers (for lidar) possible.
The deep learning concept itself did not "discover" anything, it's just a technical contraption that happens to work well for some classes of real-world problems. Granted, there were some maths advances in the eighties and nineties that made current SLAM possible, but again, new math is not "scientific discovery".
> is there a function from theorems of ZFC to {invented, not invented}?
Can you derive definitions of inventions versus discoveries from set theory? No, probably not. You can't derive the smell of a rose from set theory either though so it's probably not a very good theory of everything.
That line isn't even important to the article, it's just a bit of flowery language intended to frame the subject of myth vs. fact.
- Relativity
- Atomic nuclei
- Darwinian modern synthesis
On the technological application side, there was the airplane and mass production of cars, plus the growth of telephony and radio.
In the 21st century we have:
- found a bunch of extra solar planets but the work really started in the 90s, lol
On the application side, we have the cellphone/smartphone revolution and continued penetration of the internet, plus consumer EVs and solar panels. Not nothing, but the smartphone is the biggest change to daily life. Everything else is more just refinement of what came before.
I can't really think of other things that are profound scientific discoveries versus technical applications or filling in of minute details. We're just clearly in the far side of the S curve now, and the 20th century was the rollercoaster.
In much the same way that much of 2020's progress was actually started from the 20th century, much of e.g. the year 2060's progress will be stuff actually started from 2020. We likely systemically underestimate the use of today's discoveries simply since the big stuff mostly isn't useful yet.
I think I am underrated some math discoveries since it's not an area I follow, e.g. the Poincaré conjecture proof is probably a big deal. On the other hand, when did Poincaré make his conjecture? 1900. So in a certain sense, we are backfilling a known gap.
Language is important. "Discovery" means something just as "inventing" means something. I see these words used all the time for things like websites (Facebook/Twitter) or computer hardware (Apple products most notoriously). Something can be a wonderful and very popular implementation without being either a discovery or an invention. Often these larger things DO contain many smaller real discoveries and inventions along the way! But people always seem to be referring to the end product as a whole, which I find bizarre.