Wednesday, August 14, 2013

Novella on the heart and the mind

Neurologist Steven Novella:
There is a certain flavor of misconception that occurs when a cultural belief intersects a scientific factoid that superficially seems to support the belief. A powerful meme emerges to the effect of – science now proves what we have known/believed all along. Gurus latch onto this idea to provide apparent credibility to their mysticism. The media eats it up. 
One such meme that has been around for a while is that the heart contains brain cells, and therefore has a mind of its own, or at least is part of the human mind. There is a related meme that the GI system (the gut) also has a mind of its own. 
The notion of “brain cells” in the heart has been co-opted to support various beliefs. One artist writes:

But for me it was exciting further evidence that thinking and mind is a deep connection between brain and mind and that we need to trigger all of our senses for effective creativity and learning. 
A Times of India article declares:

It seems both heart and gut have minds of their own. Besides communicating with the brain, they might also be helping it develop, reducing depression and increasing the level of the individual’s well-being. 
Guru Joseph Pearce (who apparently likes to be called, Joe) is quoted as saying:

The idea that we can think with our hearts is no longer just a metaphor, but is, in fact, a very real phenomenon. We now know this because the combined research of two or three fields is proving that the heart is the major center of intelligence in human beings. 
He goes on to cite research about the feedback mechanisms from the heart to the limbic system of the brain. 
What are these people talking about? The primary misconception here is to confuse “neuron” with “brain cell,” followed by equating brain cells with mind. 
Not all neurons are brain cells (and not all brain cells are neurons – there are glia also, but that’s another story). Neurons are specialized cells of the nervous system that use the electrical potential across the membrane of all cells, which in neurons have evolved a special function, to trigger depolarizations that send an electrical signal down their axons which then sends a signal to another cell. 
Not all neurons are in the brain. There are neurons in the spinal cord and in the peripheral nervous system as well. 
Further, not all neurons contribute directly to the mind – conscious processes – or even subconscious processes beyond some basic sensory feedback to the brain. There is, for example, the autonomic nervous system, which (as the name implies) is concerned not with thinking but with regulating basic bodily function. This includes the function of the GI system and the heart. 
It is no surprise, therefore, that the heart and the guts will contain their own specialized neurons that participate in autonomic function... 
None of this adds up to the heart or gut having a mind. The mind is entirely the product of the brain, which of course is part of the body and is extensively connected to the body through various feedback mechanisms – hardly a surprise.

Novella is partly right. The neurons in the heart and gut aren't brain cells. They're peripheral neurons, largely part of the autonomic nervous system.

But the laypeople he quotes and derides make important and valid points. This is a fine example of the confusion that both Cartesian dualism and materialist reduction have made of the mind-brain-body relationship.

As I have argued many times before, the Aristotelian/Thomist view of the mind (Thomistic dualism) offers the most realistic and comprehensive understanding of the mind-brain-body problem.

From the Thomist perspective, the mind-brain-body problem is only a problem because our metaphysical notions of Cartesian dualism or materialist reductionism are misguided. For the Thomist, the "mind" is just several aspects of the soul--the intellect and will and some aspects of the sensory and motor acts-- and the soul is the form of the body. A human being is unitary, a composite of soul and body.

The soul has various powers. The vegetative powers of the soul are what we call biochemistry, physiology, etc. The sensory powers of the soul involve sensory perception as well as motor acts, etc. The rational powers of the soul are the intellect and the will. The hypothalamus mediates many aspects of physiology. The retina mediates visual perception. The motor neurons in the primary motor area mediate voluntary movement. The association areas of the brain mediate intellect and will.

These are not separate "parts" of a human being, properly understood. These various powers together comprise the human soul, which with the body comprises a human being. They are not parts, and they can not be reduced in a simplistic materialistic reduction. Nor can the soul (in ordinary life) be separated from the body.

The neurons in the heart and gut are aspects of a human being. While the brain appears to be critically important in mediating powers such as intellect, will, judgement, awareness, wakefulness, etc-- all powers that we think of as comprising "consciousness"-- it is wrong to think of the functions of the brain or heart or gut as being completely ontologically separable. Man is a unified living substance.

There are many ways that this unified Thomistic view of man informs science. One rather striking example is a perplexing observation by Libet and coworkers that a peripheral sensory stimulus is perceived as much as 500 msec before the arrival of the action potential in the sensory cortex. That is, we appear to feel a sensation on the skin as much as a half-second before our brain is aware of the sensation. This perplexed Libet greatly. He proposed that the brain back-dates the sensation. It receives the impulse in the sensory cortex, and then makes us consciously perceive that the sensation happened a half second before.

From the Thomistic dualist perspective, there is no problem with the inference that the sensation enters into consciousness at the peripheral receptor in the skin. The powers of sensation and awareness cannot be divided so simplistically between the peripheral and central nervous systems, as materialist reductionists are wont to do.

More in a bit on the explanatory power of the Thomist understand of the mind-brain-body relationship. 

15 comments:

  1. Michael,

    You are an idiot. Last year, I quoted to you the section in Libet's book 'Mind Time'. It's on page 72 in the section 'Antedating of Delayed Sensory Experience':

    'After skin stimulation, there's a primary evoked response, which the subject is unaware, occurring with only the delay due to nerve conduction, and the subject only becomes aware of stimulation when it persists for 0.5 seconds. And the brain is capable of antedating the awareness back to the time of the primary evoked potential'.

    This isn't what you're claiming. The action potentials from cutaneous stimulation have to reach the brain first. And then they have to persist for half a second (otherwise consciousness will be constantly bombarded with sensations due to random firings of nerve endings) before the sensation is perceived. And the brain is capable of interpreting a sensation as occurring earlier (but no earlier than when the action potential reached the brain, not when it was elicited at the nerve ending in the skin).

    This is something the brain does all the time. The position of rapidly moving objects is predicted about 0.1 seconds into the future (otherwise batters wouldn't be able to hit fast balls in baseball). The sound and vision of a person clapping appears simultaneous up to about 30 metres although obviously the vision is instantaneous and the sound takes a significant time (about 0.1 seconds) to reach the person. Over 30 metres, the synchronisation fails completely.

    The mind is a model of the external world and the person's position in it. It's an illusion. A very useful illusion, but still an illusion.

    Anyhow. A book recommendation. Suzanne Corkin's 'Permanent Present Tense. The man with no memory, and what he taught the world'.

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    1. Adm. G Boggs, Glenbeckistan NavyAugust 14, 2013 at 8:11 AM

      blabfast, you're tripping over your own ignorance.

      After all your psychobabbling about "action potentials" and baseball, you come to this:

      The mind is a model of the external world... It's an illusion.

      Is it a model or an illusion?

      Model: a standard or example for imitation or comparison

      Illusion: something that deceives by producing a false or misleading impression of reality

      Are you constantly bumping into walls because your model is just an illusion?

      Or do you just not know what you're talking about, attempting to string together ideologically satisfying snippets into some sort of verbal hoo-hah to create the illusion you know what you're talking about?

      And while you're at it, explain this for me: how does the peripheral auditory system defeat the Fourier uncertainty principle (aka the Heisenberg–Gabor limit)?

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    2. Georgie,

      When you manage to get out of your bathtub and stop playing with your toy plastic battleships, you might be able to come up with a sensible comment.

      Egnor is confusing 'action potential' with 'evoked potential'. They sound similar, but they're completely different things. Action potentials occur in nerve fibres and are 'all or nothing'. The strength of a cutaneous stimulus is modulated by the frequency of the action potentials.

      Evoked potentials occur in the brain. They're not 'all or nothing'. The strength of the stimulus is reflected in the size of the evoked potential.

      The action potentials have to reach the brain before an evoked potential is produced. It's not perceived by the person unless it persists for 0.5 seconds, and then it's antedated to the time the brain first received the action potentials, not to the time the skin was stimulated.

      The brain constructs a model of reality and the person's position in reality. This is the 'mind'. And it's an illusion, because sensory perceptions are interpreted and moved around in time and space to meet expectations. And the brain can be fooled.

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    3. Adm. G Boggs, Glenbeckistan NavyAugust 14, 2013 at 8:49 AM

      I see you carefully avoided the questions I asked.

      Or were you suffering under the illusion that I am Egnor and he (I?) was actually talking about evoked vs action potentials in my comment?

      Pity when that happens. Up your meds, perhaps?

      Or was it just a case of perseveration? Hope not!

      sensory perceptions are interpreted and moved around in time and space to meet expectations

      BWAHAHAHAHAHAHA


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    4. Georgie,

      OK. The Fourier uncertainty principle is defeated in the brain, not in the inner ear (the cochlea). It's determined by how much resources the brain allocates to hearing. Professional musicians do much better than the run of the mill member of the general public, because they've put in the effort to acquire the ability.

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    5. Adm. G Boggs, Glenbeckistan NavyAugust 14, 2013 at 9:06 AM

      How can there be more information in the brain than at the periphery. The data are being compressed all along the pathway, including the 8th cranial nerve and the superior olivary complex, and once lost that information cannot be recovered.

      You have an upgrade to information theory, too?

      Or is it just an illusion?

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    6. Georgie,

      Exactly. The brain replaces the information that has been lost due to compression. It 'confabulates' the missing information by means of experience and expectation. It's an illusion, but a very useful illusion most of the time.

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    7. Georgie,

      And the McGurk effect illustrates perfectly that hearing is an illusion. If a subject sees a video of someone saying 'ga-ga' but with it dubbed as 'ba-ba', it's heard as 'da-da'.

      The brain hears 'ba-ba' and sees the lip movements of 'ga-ga'. To make sense of the discrepancy, it's changed to 'da-da' because that fits the visual and auditory clues together better than 'ba-ba' or 'ga-ga'.

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    8. Adm. G Boggs, Glenbeckistan NavyAugust 14, 2013 at 6:06 PM

      batfark, the McGurk Effect "illustrates" no such thing, any more than the Stroop effect "illustrates" that vision is an "illusion". I hate to tell you this, but as often true, you don't have the slightest idea what you're talking about.

      If the brain were "replacing" the information, filling in unrecoverable data, then the respondent would be wrong unless the experimental context matched every respondent's personal history. That is laughable.

      But if you really think you've solved the problem, mate, e-mail Marcelo Magnasco at Rockefeller Laboratory of Mathematical Physics and tell him. Or Brian Moore, F.R.S., at Cambridge University. They'll be delighted to know the conundrum has been solved by a retired pathologist in a comment thread.

      Anthropogenic global warming, though...

      Well, that's no illusion, no matter what the data say. :-D

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    9. Georgie,

      You're typically clueless, engaging in your pattern of information free abuse.

      Vision illustrates perfectly the fact that sensory inputs are severely compressed with most of the information thrown away. Which the brain then restores by a process of memory, expectation and experience.

      The human retina contains 126 million photoreceptors (it's a 126 megapixel camera) with 6 million cones (the receptors responsible for colour vision and fine vision concentrated in the central retina) and 120 million rods (peripheral vision, not fine vision, sensitive to low light and movement).

      And all of this information has to go through an optic nerve with less than 1 million axons.

      It's severely compressed, with little more than central vision and a vague impression of peripheral movement.

      And the brain then puts the information back. It confabulates the information it puts back, so it's an illusion too. A very useful illusion, but still an illusion, which can and often is fooled.

      You're an idiot.

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    10. Adm. G Boggs, Glenbeckistan NavyAugust 14, 2013 at 8:57 PM

      I understand visual psychophysics, batfark. I also understand compression and signal processing. I know about the optic nerve.

      The eye is not a "megapixel camera". That is an analogy, which fails to explain either Mach bands or the spatial transfer functions.

      Long-term memory has nothing to do with the Stroop effect or the McGurk effect.

      The brain does not "put information back".

      The brain does not "confabulate", whatever the hell that is.

      Long-term memory has nothing to do with the Stroop effect or the McGurk effect.

      Batfark: "You're an idiot."

      Then email Marcelo Magnasco at Rockefeller Laboratory of Mathematical Physics and Brian Moore, F.R.S., at Cambridge University and tell them your theory. And while you're at it, send a copy to crank.net.

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    11. Georgie,

      You're still a waterlogged idiot. It's not 'my' theory. It's standard basic neuroscience 101.

      I'm suspicious of physicists attempting to use computers to mimic the human brain - which is the most complex structure known in the Universe.

      You learn to see. You learn to hear. If a baby has a congenital cataract or 'lazy' eye, it has to be corrected early, otherwise the person will never develop vision from that eye. The visual cortex remodels itself to be able to interpret signals coming from that eye.

      It's be more impressed with physicists' attempts to model brain function if they had a computer system that manages to do what the developing brain does very well - remodel itself to perform its unique functions (and each person is unique in the pattern of abilities).

      I never said that the Stroop effect or the McGurk effect had anything to do with long term memory.

      The brain does confabulate. Where do you think false memories come from?

      What do you think the brain does?

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  2. Also, no one has attempted to support Egnor's bullshit assertion that Libet's work demonstrated that a person is aware of a cutaneous sensation from the time the peripheral nerve receptor is stimulated. As evidence that the peripheral nervous system is self aware.

    Not true. The brain is aware of a stimulus only from the time it reaches the brain. And when it persists for half a second, it's transmitted to the 'mind' as a perception that already has lasted half a second.

    Egnor has problems with reading comprehension. And also is clueless regarding basic neurophysiology, confusing 'action potential' with 'evoked potential'. Worrying in someone who's a neurosurgeon.

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  3. bach:

    [The brain is aware of a stimulus...]

    The brain is an organ made of meat, and it is aware of nothing.

    The person-- the composite of body and soul-- is aware.

    Your metaphysics is materialist/reductionist, and wrong.

    [confusing 'action potential' with 'evoked potential']

    An EP is a kind of AP. Are you claiming that an EP is not an AP?

    What then, pray tell, is it?

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    1. Michael,

      No. An evoked potential isn't a kind of action potential.

      You do understand EEGs don't you? They show evoked potentials in part. Nerve conduction studies show action potentials. Action potentials are 'all or nothing' of defined amplitude and short duration. Evoked potentials are variable, greatly, in size and amplitude, reflecting many neurons (and also the supporting astroglial supporting cells). An action potential is in a single neuron.

      You're clueless about neuroscience, as shown by your inability to understand what Libet actually wrote. So I'm supposed to agree with your metaphysical bullshit about the mind?

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