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Neurosurgeon Michael Egnor on the Timing of Sensory Processing

One neuroscientist, encountering the timing, made up a theory that didn’t really work, but he was a great neuroscientist anyway

Neurosurgeon Michael Egnor did a recent podcast with host Arjuna Das at Theology Unleashed, “where Eastern theology meets Western skepticism.”

In the previous segment, Dr. Egnor talked about the troubles of being a non-materialist medical scientist, including demands that he be fired and death threats and so forth. In this segment, he talks about the meaning of “soul” in philosophy. Not a “spook” of some kind but common sense reasoning about life and death:

Arjuna Das: So there’s a delay in how long it takes for the brain to process visual sensations compared to auditory sensations. So it’s a half second delay and this creates a problem. … We have no free will then. (01:57:50)

Michael Egnor: If I can just take a moment, that particular observation about the delay in the sensory processing was explored in considerable depth by a physiologist in the mid-20th century named Benjamin Libet . And I haven’t had a chance to talk here about Libet, but his work is fascinating. He’s most famous for his work on free will. But to me, actually, his most interesting work was on the timing of sensory processing. He did a series of experiments in which he would have people have their finger pricked, and they would record on a clock that could record time to within a resolution of about 10 milliseconds when they felt the finger prick. And he had electrodes on their scalp that would record when their brain registered the sensation from their finger. And what he found was that they felt the finger prick within a few milliseconds of the moment that the finger was pricked, but their brain was silent for about half a second, showed no activity at all for about half a second, and they felt the finger prick almost instantaneously with no brain activity associated with it. (01:58:44)

So essentially they were feeling their finger without their brain being aware of anything happening in their finger. And he was utterly perplexed by it. He was blown away. And he said that the way he interpreted it was that the brain would “backdate.”

That is, the brain would feel it a half second later. And then you would be tricked into thinking you felt it at the moment it happened.

Of course, I think that’s a bunch of hand waving. I think what that means is that … the soul basically is the entire body. It’s not just the brain. We tend to think of the brain, again, as this Cartesian theater. And it’s another good argument against the Cartesian theater. We feel a finger prick in our finger, not in our brain. What the brain does, I think, is it interprets it. The brain function is not the primary way that we feel things or see things or hear things. The brain is what allows us to understand them. The brain generates the more complex perceptual and imaginary processes that allow us to make sense of it. But the actual perception, I think, occurs in the sensor, not in the brain. 02:00:04)

Arjuna Das: So this fits into a Vedic idea that consciousness, as described in Bhagavad Gita, is that which has spread all over the body, and the soul is described as seated in the heart. And blood is also spread all over the body … so blood is carrying consciousness all over the body and our ability to… There’s neurons in the fingers. So it could be that our sensation of the finger prick could be in the neurons in the finger directly. And then the brain later adds interpretation. So if the soul is seated in the heart, then the fact that we’re experiencing things going on in the brain, there’s also a distance thing going on there, oh, I guess you’re well outside of the brain model at that stage. (02:01:21)

Michael Egnor: Sure. I think the Aristotelian or Thomistic understanding of the soul can help here … The soul is the act of principle of the body. In the Aristotelian way of looking at it, if you take a living human being and the same human being a moment after he’s dead, you subtract everything about the dead body from the living person, what remains is the soul. So the soul is essentially a set of abilities, a set of powers. And so they don’t sit anywhere. They are the body, they are the living body minus what would be there if the person were dead. (02:02:10)

Arjuna Das: The Vedas describe the soul as being the size of a point. And of course a point has no physical dimensions. (02:03:01)

Michael Egnor: Precisely. So it doesn’t make any sense to speak of the souls as having dimensions. I think what St. Thomas Aquinas. would say is that, if you want to speak about dimensions or locations of immaterial things, the most you can say is their dimensions or their locations is where they act, but they aren’t really there. So the soul isn’t really there. It acts there. The soul doesn’t have a there, it’s not a physical thing. It doesn’t have locations or more dimensions. (02:03:10) …

.Arjuna Das: What could be meant by the soul being seated in the heart? It is described like that. So the other thing I was going to say is we do have some delay in our cognitive abilities. You’re closing a car door and you realize, oh, no, I need to grab that thing. And you watch your arm shut the door, unable to stop it. (02:03:50)

Michael Egnor: Well, a fascinating aspect of the neurosurgical management of pain is that there are operations that have been developed to help people who have chronic pain. And one kind of operation stimulates the cortex so that as you place electrodes on the surface of the cortex that are implanted in the body, and you stimulate the cortex, and that suppresses the pain. If pain were experienced by activation of the cortex, then simulating would make the payment worse. But in fact, it seems that the role, at least the cortex plays in the sensation of pain, is that it suppresses it, it doesn’t mediate it. And so there are a lot of aspects to the sensory system that don’t fit the computer or Cartesian theater model of the mind. The brain’s role in my view in sensation is largely the interpretation of sensations. And to some extent, the suppression of unpleasant sensations. (02:04:12)

But I believe that the sensations themselves are experienced if one wants to give a location to them, in the sense organs, not in the brain itself. Be it the pain receptor in your finger or the retina of the eye.

Arjuna Das: Also they train people in the military, if you’re following somebody, like a spy, if you’re following somebody and you don’t want them to see you, don’t look at their back, look at their feet. If you look at their back, they’ll turn around and look at you. So the idea here is that our vision, our sensation of the world, our visual perception is actually contacting the world. So we all have the sensation of being stared at, we’re looking at somebody and the person just turns around and lock eyes with us. They don’t look around and scan and find us, they look around and stare directly at us, or we do the same thing. We just turn around and lock eyes with somebody who happens to be staring at us. (02:06:43)

Michael Egnor: Absolutely. I very much believe that. And the interesting thing I think is that if one looks at neuroscientific results, and there are many others besides the ones that we talked about, neuroscience is very supportive of the notion that there are immaterial aspects to the human mind. And it’s totally open to these kinds of things. Materialism fails across the board to explain any of this.


Here are partial transcripts and notes for the first hour and fifty-six minutes, starting from the beginning:

Why neurosurgeon Mike Egnor stopped being a materialist atheist. He found that materialism is just not working out in science. Most propositions in basic science are based on mathematics and mathematics is not a material thing.

How science points to meaning in life. The earliest philosopher of science, Aristotle, pioneered a way of understanding it. Neurosurgeon Michael Egnor talks about the four causes of the events in our world, from the material to the mind.

How we can know mental states are real? Mental states are always “about” something; physical states are not “about” anything. Michael Egnor argues that doing science as a physicalist (a materialist) is like driving a car with the parking brake on; it’s a major impediment to science.

What’s the best option for understanding the mind and the brain? Theories that attempt to show that the mind does not really exist clearly don’t work and never did. Neurosurgeon Michael Egnor reviews the mind-brain theories for East Meets West: Theology Unleashed. He think dualism makes the best sense of the evidence.

How did Descartes come to make such a mess of dualism? Mathematician René Descartes strictly separated mind and matter in a way that left the mind very vulnerable. After Descartes started the idea that only minds have experiences, materialist philosophers dispensed with mind, then puzzled over how matter has experiences.

How philosopher John Locke turned reality into theatre His “little theater in the mind” concept means that you can’t even know that nature exists. It may just be a movie that’s being played in front of your eyes.
Aristotle and Aquinas’s traditional philosophical approach, Michael Egnor argues, offers more assurance that we can truly perceive reality.

The brain can be split but the mind can’t. Neuroscientist Roger Sperry found that splitting the brain in half does not split consciousness in half. It just gives you a rather interesting, but very subtle set of perceptual disabilities.
Neurosurgeon Michael Egnor has split patients’ brains, while treating serious epilepsy, and the results are not at all what a materialist might expect.

How the split brain emphasizes the reality of the mind. Fascinating research following up Roger Sperry’s work — which showed that the mind is not split when the brain is — has confirmed and extended his findings. One investigator, whose work followed up and confirmed Roger Sperry’s, called her split brain findings “perceptual disconnection with conscious unity.”

The brain does not create the mind; it constrains it. Near-death experiences in which people report seeing things that are later verified give some sense of how the mind works in relation to the brain.
A cynical neurosurgeon colleague told Michael Egnor that he could not account for how a child patient’s NDE account described the operation accurately.

Why do some people’s minds become much clearer near death?
Arjuna Das and neurosurgeon Michael Egnor discuss the evidence for terminal lucidity at Theology Unleashed. Dr. Egnor argues that the brain and body constrain the mind. When dying, they may constrain it less, resulting in sudden end-of-life lucidity.

Epilepsy: If you follow the science, materialism is dead Continuing a discussion with Arjuna Das at Theology Unleashed, Dr. Egnor talks about how neurosurgery shows that the mind is not the brain. Neurosurgeon Michael Egnor addresses objections to his finding that epilepsy shows that the brain does not create the mind.

Non-materialist science is wanted — dead or alive. Exploring a non-materialist approach to the mind has included a death threat for neurosurgeon. In neurosurgeon Michael Egnor’s view, materialist scientists are almost always theoretical scientists. They’re not doctors or engineers.


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Neurosurgeon Michael Egnor on the Timing of Sensory Processing