Wednesday, October 7, 2015

External Surfaces of the Brain

Check out my recent posts on the Screen Argument before reading this!

Please note this is super, super simplified to make it understandable!

Brain cells have a lot in common with all the other cells in our body. In fact, there is a surprisingly small number of genes that differ between neurons (one kind of cell found in the brain) and, say, a hepatocyte (cell in the liver).

If we look at the external surface of the brain, we can pick out which parts are responsible for specific parts of our consciousness. These areas are called "Brodmann's Areas".

Let's look at a few examples.

Areas 1, 2, and 3: The primary somatosensory cortex, responsible for touch.
Area 4: The primary motor cortex, responsible for voluntary movement control.
Area 17: The primary visual cortex, responsible for vision.
Area 41: The primary auditory cortex, responsible for hearing.

I think this may give some hints for progress on the Screen argument.

Physically, the neurons in these different regions are very similar to one another--all of them are part of the cerebral cortex! (The cerebral cortex is the part of the brain that you think of when you look at a brain--the external surface)

There are many brain regions deep to the cerebral cortex with very different anatomy and physiology.

Anyway, it isn't the cell type that distinguishes functions across Brodmann's Areas. It's the difference in organization--the different connections that are made by the neurons--that differentiates the function.

But just consider HOW DIFFERENT these regions are as you experience them! Vision (Area 17) is WAY different than touch (Areas 1, 2, and 3)! Hearing is VERY different than movement control!

What I'm pondering is the relationship of this info about the brain to the Screen Argument. If our experiences are purely physical, we ought to be able to find our experiences in the brain. We can certainly point to the spots that correspond to our experiences (see that picture up there, we are memorizing that puppy in medical school right now, I dare you to point out a comprehensive pattern), HOWEVER, when we point to the spots, we see pretty much the same thing--neurons.

But then if we point at the unique patterns in each Brodmann's Area, we see a pattern of neurons, not a Screen (we don't observe, say, a picture of something you are looking at, or an experience of pain, or an audio recording that you are listening to). We just see neurons.

Read my other posts on this subject, and you may start to see why I don't think consciousness is reducible to the physical brain. Consciousness is consciousness, it corresponds to the brain, it doesn't equal the brain.


  1. If you stand in front of a chair and look at it, then walk around to the back of it, do you expect it to look the same? Would you conclude that there are two different chairs because it looks different from each perspective, or would you follow all the rest of the evidence which indicates it is just one chair viewed from two different places? I think I know the answers to those questions, so the real question I want answered is why this situation is not analogous to the screen argument. Is it just a matter of the extent of dissimilarity?

    On a separate but related note, I wonder if you would say that visual screens exist for the planarian? Is phototropism a type of screen?

    1. Yo MoF!

      Good to hear from you!

      I would say that there is one chair viewed from two different places.

      I think this situation is not analogous to the argument I made. This, however, would be analogous: Take a photo of the front of a chair, then take a photo of the back of the chair, are the two photos different? Yes the two photos are different.

      Regarding planarians, "the kings of the flatworms", we can't know whether or not visual screens exist for them--just as I couldn't know whether or not visual screens existed for advanced robots, or for other humans, even. The point is that we can't detect visual screens in the physical world--so I have no way of telling whether or not a planarian experiences a visual screen.

  2. Hi Josh,

    Oh so much to say, so little time! Let me just start with saying that I might put together a response to articulate where I think this argument is going off the rails - which is not to say that it's completely wrong, but you know me - argumentative to a fault. As a prelude to that, I guess I must ask ... who is it that actually thinks that consciousness is "reducible to the physical brain"? And, what exactly is it that you mean by this phrase? And how has Dr Velasco's revelation about aphantasia (real cutting edge stuff there) affected your thinking (if it has)?

    I'll leave it there for the moment.

    1. I've put my response together - HERE.

      Enjoy :)

    2. Neo!

      Thanks a ton for writing a response article. I shared it on all the social media. XD

      I will respond back soon!

    3. Physicalists think that consciousness is reducible to the physical brain--so many scientists, skeptics, and atheists. Anyone that adheres to 'reductionalist naturalism'. Examples: Neil DeGrasse Tyson, Stephen Hawking, Richard Dawkins.

      "Reducible to the physical brain" means that consciousness is purely physical. There is nothing non-physical about consciousness. It's just physics.

      Regarding aphantasia--very, very interesting. I would say that these individuals lack a part of their consciousness--they lack visual screens. I need to learn more about the condition before I could say more!

    4. That was soon :) and I was wondering why I suddenly got a bunch of traffic from Facebook ...

      I do need to be more careful with the terms "physical" and "thing". When I talk of things, I usually mean concrete things (like a chair) as opposed to process things (like a waterspout) - but of course a chair is really a process thing as well, just at a much slower pace. And when I say "physical" I often mean "concrete" - as in "a physical body". The various uses of these terms allows equivocation, and we should try to avoid that :)

      That said, in terms of just being physics, yes - the brain is physical, neurons are physical, and I would suggest that consciousness, despite being an emergent feature, is - to the extent that it "exists" at all - physical. I just don't think that the brain itself is consciousness - I suspect that it's more about the interface of the brain with the outside world, so it needs more than brain ...

  3. "HOWEVER, when we point to the spots, we see pretty much the same thing--neurons."

    I still think this is a little specious - we don't just see neurons, we see neurons in a very specific arrangement, firing in a very specific pattern.

    To say that this pattern "is not a picture" seems akin to saying that the ordered magnetic bits on a hard drive which represent a .jpg file "are not a picture" - they are absolutely an encoded representation of a picture, and saying that this "is not a picture" seems like a distinction without a difference.

    Aphantasia highlights why it is reasonable to believe that there is no non-physical component to our consciousness. Parts of what we think of as our consciousness can selectively be physically located in the brain and destroyed, which means their existence is purely physical. How could brain surgery destroy part of your soul?