Anatomy Of The Brain

Last week I wrote in brief about the differences between conscious and non-conscious thought, and how experiments show humans use both. Even the most primitive animal brain is an extremely complicated organ, and the human brain is obviously the most advanced brain we've encountered. Conceptually there are three main sections of the human brain, corresponding to the evolutionary processes that produced the brain.

Pardon the aside, but I wanted to say a word to the Christian readers who believe in Intelligent Design instead of evolution. Feel free to interpret "evolution" with "how God chose to create life". Your personal belief about how humans came to exist won't change your interpretation of what I have to say, so don't let my choice of language get in the way. Remember, I was a Christian for 30 years. I was taught creationism by my parents. In high school I believed the theory of evolution, and just said "God used evolution to create humans". Now I just think "humans were created through evolution". I still think people who believe in Intelligent Design are wrong given the data, but I see no reason to be condescending or judgmental about it.

As I was saying, there are three main sections of the brain. At the core is the so called "Reptilian Brain", or more formally the brain stem. This section handles basic reflexive responses such as "fight or flight", mating instincts, and the fear of other species. It also handles exactly one emotion: rage. Next is the Mammalian Brain, or Limbic system. This is the area of the brain that handles all other emotions, as well as concepts like family, culture, and attachments. Some aspects of conscious thought and self-identity are handled by the mammalian brain as well. Last is the Neo-cortex, which is responsible for higher level thought such as speech, reasoning, imagination, and speculation.

While there's a clear physical boundary between the reptilian and mammalian brains, the division between mammalian (limbic) and neo-cortex is not as clear, and there seems to be a stronger bleed between the functions. For example, some conscious thoughts are handled by the mammalian brain while others are handled by the neo-cortex.

Humans have all three brain sections, as do higher mammals such as other primates and larger mammals. Small primates such as rodents do not have a neo-cortex, although they do have the limbic system and reptilian brain. And as the name implies, all reptiles have the reptilian brain, but lack the mammalian brain and neo-cortex. So the brain sections correspond to different evolutionary forks. The primary feature that separates mammals from reptiles is not hair or internal gestation, but a more advanced brain.

If that's true, then reptiles don't actually have conscious thought. They simply respond to stimuli in the same fashion every time. But mammals, having a memory, can learn from past experiences and modify their behavior. Perhaps this is how mammals survived the dinosaurs after a natural disaster hit the earth. Dinosaur brains weren't programmed to handle the "meteor crashed into the earth and all your normal food dies" situation, whereas mammals could learn to find new food sources.

In computer science terms, the reptilian brain is analogous to a state machine, or a simple circuit board. It's pure hardware, and if you give it the same set of inputs, it produces the same set of outputs every time. It has no memory. The mammalian brain is more like a simple computer program, in that its responses are based both on sensory input and on past memories and experiences. Running the same computer program multiple times might produce different results. Mammals have the ability to learn throughout their life while reptiles do not. And since the neo-cortex handles imagination, reasoning, and "what if?" scenarios, it's closer in function to an operating system. An OS can run multiple programs in parallel, similar to the neo-cortex's ability to think about multiple thoughts at the same time, even conflicting thoughts.

This biological framework provides an interesting context from which to answer the questions "What are emotions?" and "Can a computer have emotions?" Some day I'll write on that, but there's a lot more to say than should be stuffed at the end of this column. In the meantime you'll just have to speculate.

Armchair Neuroscience

I'm really grateful for my undergraduate education at the University of Chicago. I believe it's the best liberal arts school in the country, in large part because it lacks the name recognition of Harvard or Yale while still placing academically in the top ten undergraduate institutions in America. No one goes to the University of Chicago for the fame or connections they might get at Harvard, and as a result the school attracts only those students who really want to learn. At the University of Chicago, they teach you how to think and analyze everything.

The joke in college was that a University of Chicago student didn't need to know anything about a subject to have an opinion on it. This is pretty much true. I distinctly remember getting an A on a paper about The Brother's Karamazov when I had only read the first quarter of the book. The trick was to relate the concepts discussed in class with the material I had actually read and with other texts read in that class. While I'm sure my professor would have been mortified to find this out, it speaks a lot about learning to analyze abstract concepts and come to conclusions that happen to be right.

In other words, The University of Chicago taught me to bullshit well.

Most of the time I talk about a topic, I really do understand the subject matter. But I'm not willing to let a lack of expertise or study prevent me from sharing my opinion, so today's topic is neuroscience. As a disclaimer, I've never studied this subject in an official capacity in my life. All the information I have is from personal reading into other studies, most of which are (I think) peer reviewed.

There! That's a more accurate disclaimer than you'll hear from any journalist, and yet they are often no better qualified than I am to write about these topics. In particular, I recently read an article on msnbc.com that hypothesized that your brain could be controlled by an inner zombie.

Yes, that's really their conclusion. And by "conclusion" I mean "hypothesis supported by circumstantial evidence that's phrased as a question so no one can refute your claim because you're not officially making one". Since there's no challenge in ridiculing a claim like this, let me instead give a fair and impartial summary of the article. Then I'll rip it to shreds and propose a hypothesis that better fits Occam's Razor by several orders of magnitude.

I'll admit the term "inner zombie" is just a term chosen to generate interest in the article. And in some sense it worked-- I'm linking to it. All they really mean by inner zombie is a thought process that's not conscious and not (always) connected to the rational decision making. The article cites some studies where people are blinded by deactivating the visual processing section of their brain, and then shown a word. The people have no conscious knowledge of the word, but when they are asked to "guess" what word might have been shown, they properly guess the word with much higher than expected accuracy. There's also a study that shows people who are temporary blinded can still reflexively react to visual information they can't see. And while the article doesn't mention it, there's also a study done on people who are blind because their brain doesn't process images even though their eyes are fine. Compared to other blind people, these people do a much better job than of dodging obstacles while walking down the street, like other people or sign posts.

I'd like to note that these results are all from real, peer reviewed studies. Scientists aren't questioning the validity of these results. But they also aren't jumping to the same conclusion that MSNBC did. Here's the basic argument the article makes:

1. People show the ability to reflexively process and react to visual information even when they consciously report blindness.
2. Therefore an unconscious process has control over their conscious minds.
3. Perhaps all consciousness is controlled by these unconscious processes and consciousness is a myth.

It's step 3 that doesn't make any sense. Sure, humans have unconscious processes that handle the same information conscious sections of the brain handle. But why does that mean the whole brain is controlled by the unconscious part? Given our daily experience, I'd suggest that the reverse is true. Our general actions are primarily controlled by conscious processes, and only when consciousness shuts off do the unconscious sections take control. There's no reason to suggest consciousness is a myth and a "zombie" is "controlling your brain".

But the brain is a really strange organ. The reasons the brain work this way are rooted in the differences between human brains, standard mammal brains, and the reptilian brain. Next week I'll talk more about these things and explain why I think dogs have consciousness but lizards do not.