Neurobiology and Behavior, Week 11

I found McGurk effect, Blind Spot test, and Checkerboard exercises in this week’s classes very interesting and fun. Examples always make abstract ideas that can’t be examined by eyes more approachable and easier to understand. But in these examples, we could even do it to ourselves and see it happening and it was really fun and educational at the same time. However, at first they were just fun, but then I thought “I can’t trust my brain!” I want to see and things the way they are and don’t have them changed by the time those information reach my brain. I want to hear “dada” when he says dada, I want to see a black dot if it is on the paper, in front of me, and I want to see the two boxes on the Checkerboard as same colors when they are same colors. I always assumed “healthy” brain to be more “absolute” in receiving information, but in fact I feel very vulnerable to outside effect and can’t trust what I see or hear.

 I had surgery on my eyes this past summer to finally correct a long-lasting case of exotropia (lazy eye).  All my life I had convinced myself that if I just concentrated on not letting my eyes "wander," I could fix the problem and avoid surgery.  Imagine my surprise when the optometrist revealed that the problem had nothing to do with the eye muscles and everything to do with my brain -- especially when the surgery involved tightening the muscles behind my eyes.  Apparently, the brain sends a signal to the eye to wander.  As soon as the eye wanders, it goes blind; in other words, if my eye wandered up and left, I still wouldn't be able to see anything in my upper left visual field with that eye.  To correct the problem, they could, theoretically, fix that misguided brain signal -- but the easier fix, naturally, is with the eye muscles.  So the brain signal is still coming, but the muscles are tightened, restricting wandering.

When one of our eyes goes "blind" like mine did, our depth perception is compromised (Try going through a day with one eye closed).  Why, then, was I able to grab things in front of me, even when my eye "wandered"?  Why was I allowed to drive?  Where is the control center for our depth perception?

After our very interesting vision experiment, I was surprised at how sophisticated our brain is, and how we are all constantly "deceived" by ourselves.  After class, I did that cross and dot experiment again with a piece of paper full of text, and it turned out that my brain actually filled in some text at the blindspot. This reminds me that when I was little, I once wondered why we couldn't recall every detail of a picture even though we remembered the image.  Now it all make sense - we can't recall the details because we never really remembered them. Perhaps this is why our brains can process images so fast? I often play with Photoshop, and it sometimes frustrates me because the image files can be very space consuming. Apparently computer softwares don't use the same image saving mechanism as we do. I guess our brains must be very good at selectively storing certain parts of images, so we could have an outline of the scene but wouldn't be fatigued by those trivial details.

And the checkboard. I tried to drag the B square in and out of the board very slowly, and was amazed to see (at least I felt I did) the gradual change of color when it was passing through the grid. I think I can never look at my brain the same as I used to anymore.

    In class this week we discussed that while sensory signals constrain what you can experience, they don’t fully define it. The nervous system interprets what we see and how we see it. The brain constructs the world around us, given visual or auditory input. So how do we know that what we’re seeing is really true? Is there any “correct” way of seeing the world?
   Autistic individuals have been known to see or feel things differently, and more visually than other individuals. This does not mean that their eyes “see” differently, but rather that their brains interpret information differently and that this information is integrated into the brain with perhaps a greater connection to their thoughts. Temple Grandin, an autistic woman who has a Ph.D in animal science and works to design more humane methods of holding livestock, has described herself as a “visual thinker”. In her novel, Thinking in Pictures, she says,
    “Spatial words such as "over" and "under" had no meaning for me until I had a visual image to fix them in my memory. Even now, when I hear the word "under" by itself, I automatically picture myself getting under the cafeteria tables at school during an air-raid drill, a common occurrence on the East Coast during the early fifties. {…} Adverbs often trigger inappropriate images -- "quickly" reminds me of Nestlé’s Quik -- unless they are paired with a verb, which modifies my visual image. {…} As a child, I left out words such as "is," "the," and "it," because they had no meaning by themselves. Similarly, words like "of," and "an" made no sense. Eventually I learned how to use them properly, because my parents always spoke correct English and I mimicked their speech patterns. To this day certain verb conjugations, such as "to be," are absolutely meaningless to me.”
    Temple’s experience with visualizing words, concepts, memories, innovations, and in effect her entire world, is similar to many individuals with autism. They seem to understand better what they see (and the images their brains are capable of creating) than what they hear in conversation, or school (what we define as language). Perhaps the visual processing areas of the brain are fortified by stronger and vaster connections in autistic individuals and this leads them to rely on and think more using vision over language. There do seem to be certain advantages to thinking visually, as Temple is able to map her innovations in every possible situation, with different sizes of livestock and different variables. She can visualize mistakes in her designs and correct them, before finally writing them down on paper. She is very attuned to the behaviors of animals as well. But there are also advantages to being able to think with words, (for example, the ability to connect with other human beings). What causes the pictures seen by the eyes and interpreted by the brains of autistic individuals to be more vivid, more thoroughly integrated and more deeply relied upon in these individuals?

Here is a link to the first chapter of Temple Grandin’s book Thinking in Pictures.
Here's a link to the trailer for the movie they've made about her life. She is a fantastic woman and is considered a leader in animal welfare and autism rights campaigns.

Synesthesia is a condition in which one perceives the world through the amalgamation of two different senses. For example, people are able to see a color when they hear a certain pitch. But would it be possible for the same person to hear a pitch when they see a certain color. Would this unusual perception change over time? For example, if a person heard a certain pitch and saw the color blue, would the same person see another color corresponding to the same pitch later  in life? If this were true, then synesthesia would be somewhat like a dream, which changes with our emotional state of mind.Since these neural connections in the brain causing synesthesia are random and illogical, would it be possible to undo these connections through the process of learning? If a repetitive activity is able to create a central pattern generation, which can be dismantled through lack of use, could the  neural connections causing synesthesia be dismantled?

I found our discussion this week about the sensory side of the nervous system very interesting. Being nearsighted, I have always wondered about how vision works and how it affects our sense of reality. I am still in awe of the blind spot test. Before our discussion I had never been conscious of my blind spot. The demonstration in class was remarkable; I can’t believe that my brain fills in the blind spot by guessing what is most likely there. I can’t help but wonder now what is and what isn’t a construction of my brain. What is reality? Although I understand why my brain must fill in my blind spot, I can’t help but feel a little bit betrayed by my brain because it is lying to me and making things up. I also found the McGurk effect very interesting. I had never realized how much of what we hear is a function of both what we see and what we hear.  

I am very surprised by how much of our perception is influenced by the unconscious factors we discussed this week. The McGurk Effect, in particular, demonstrated to me just how much of what I am seeing I am not actually “seeing.” As we discussed, when you see something it is actually the aggregation of many point sources of light. Then, our brain is taking in a series of snapshots and tying them together subconsciously. So this makes me wonder how this process actually occurs. If you imagined this from the perspective of a computer (or a camera for that matter), you would have to be continuously taking in images, sorting them based on where you had aimed the camera (where our eyes were looking), and then storing them in a short term memory. Then, you would have to be accessing this data and continually updating it, deleting the old memories and replacing them with new ones. Imagine you pan the camera around the room and then hold it still in one direction. The brain has to know to keep the older images of the surrounding area because it has not updated those views during the immobile period.

So imagine you’re in a very dynamic environment (like looking out the side window of a train). How does your brain process an entire frame of constantly changing image? In that situation, you can’t really focus on much for very long, but still you are able to perceive the intricate details of the landscape.

Our discussion made me think about those clocks that move a wand back and forth very quickly to display an image. (If you don’t know what I am talking about, check out http://www.youtube.com/watch?v=O7errqgg8CA). They must work because our brain takes the images and stitches them together. If we didn’t normally store images and then reference it, we would just see single LED lights. Instead, we are able to stitch together a comprehensible image.

We don’t actually know what’s really going on in the world around us. Instead, we just perceive whatever our brain has constructed for us. Hence, there are really two ways that we could be affect what you see. First you could put on sunglasses, or look through a colored glass pane…this would affect what you see. But maybe you could also alter the way that your brain stitches together the images. If this alteration happened subconsciously (or without your awareness), is there any way you would know? Does this have anything to do with the way that drugs may affect our perception of the world? Imagine you unwittingly took a pill that caused hallucinations but didn’t affect consciousness. You wouldn’t know that you were hallucinating. If you’re hallucinating, your eyes are still inputting the same point sources of light. Despite this, you may actually see things that don’t exist. Hence, those hallucinations must be occurring in the processing of the visual input. Our brain might take in point source information from a lamp and see a monkey. I am curious to learn more about how that connection is made.

    Also, check out this video on synesthesia. He perceives numbers as having a sensory component!

    http://video.google.com/videoplay?docid=4913196365903075662#

   
 

We were talking in class on Thursday about the fact that the human system for vision is not perfect, just a system that happens to work most of the time.  It’s strange to think that vision is more likely to not work well than to work well, but it does go a long way towards explaining why so many people need glasses, and most people end up needing them as they age. It reminded me of the argument for intelligent design, that something as complicated as the human eye could not have evolved without the influence of a creator. The fact that the human eye doesn’t work perfectly is good evidence for the fact that it is a product of evolution. Evolution simply favors what works, even if it isn't perfect. A "designer" wouldn't likely have created something that doesn't work perfectly, and certainly wouldn't have created something that doesn't work well much of the time.

The idea that an unconscious part of the nervous system fills in the gaps in your vision, along with the fact that even if you know about the gaps in your vision you can never actually see them, raises some interesting questions. To what degree does unconscious mind control behavior? How much of our unconscious behavior can we change if we become consciously aware of it? It’s also strange to think much of the information that is transmitted to our eyes is thrown away before it reaches the nervous system, and it just fills in the gaps. How much of the time is what our nervous system fills in different from what is actually there?

In light of our discussions this week about the visual system and the great deal of information that is actually constructed by the brain, it seems to me that humans actually have very limited control of our behaviors. We respond to stimuli, yes. But we are actually responding to stimuli that has been falsified in such a way as to make it easier for the human brain to understand it, process it, and create appropriate outputs for the inputs.

So what is the point of the I-function, then? Is it just to interpret the stimuli which have been processed and edited? Why can't the I-function discern what has been edited by the brain and what are in fact the raw details? Shouldn't there be some function that can reconcile the differences between the two realities?

            I’ve been wondering about the benefits of having our nervous systems make up information to fill in the gaps in our sensory inputs.  Is it faster to fill in the gaps in our vision automatically from pre-existing patterns or based on the rest of the image we are seeing?  Is it more efficient? I think it’s mostly beneficial that we’re only able to focus on a small area at a time while our nervous systems fill in the rest of the details.  I’d go crazy if I had to notice every detail of my surroundings at all times.  It would be too much information to process. For instance, as I’m typing this I’m sitting at my desk and there are sticky notes all over it, each a reminder of something else I need to get done. Right now I am very glad all I can see of them are their bright colors and not the words written on them.  I am similarly glad I can’t see what the people around me are writing in their notebooks in class. I can see them writing, and if I were to focus on their papers I could read them, but I don’t need to in order to write my own notes.  We’ve talked about how our senses can’t and don’t relay all possible information about all possible phenomena to our nervous systems and how that means our nervous systems are not perfect and are very limited.  It seems to me that our senses take in too much information at once and that it is in fact the rest of the nervous system that is not adequate to process it all.  

            I’ve also been wondering whether it’s easier to observe details or to ignore them when we don’t need them.  I’m assuming everyone has had the experience of having someone point out a detail that they hadn’t noticed before and subsequently not being able to un-see that detail.  The same thing happens with the other senses, too. I think the importance of details is determined by whether those details have become part of the I-function.  We’ve already pointed out how engaging the I-function can slow and limit the behavior of the rest of the nervous system, and I think this phenomenon is another example.   

This week we talked about how everything you see is a constructed best guess from our brains.  While I have heard this before, I do not quite know how to rationalize it.  If everything we see is our "guess" of the world, only from similar upbringings or culture surroundings would we be able to see the world in a similar fashion.  While our eyes all work the same, we are all different people who interpret situations differently.  This led me to think of the validity of eyewitnesses during murder trials or any other trial.  Based on what we learned this week, the eyewitnesses to certain crimes could have not seen the full crime at all but their brains filled in the blanks for them making them think they did.  Our brains are programmed at "filling-in-the-blanks", but that can have some serious consequences if the wrong person is put away in prison for 10 years.  When our brain fills in the blank, what is it based on? With the cross and dot illusion, our brain filled in the blank with the pattern behind it based on a pattern we had seen before. But in the case of seeing a crime, what do our brains draw from? Are there certain cultural pattern we are used to seeing? Or does the brain give the best "guess" at who we thought we saw commit the crime? 

 First of all, I am very excited we have been talking about vision! Vision has always fascinated me, especially the role the brain plays in what we perceive. The fact that our brain "lies" to us makes a lot of sense with respect to corollary discharge, which checks expected information with perceived information. Since we do not receive any input from the spot where our optic nerve goes back into our head, our brain has to make up what would be there based on what it expects. I like to think about how much we perceive and to what extent it is "real" or just what our brain is telling us. There is really no way to know. If you have never seen the Matrix before, now is probably a good time with the context of our class discussions and where they might lead. If our brain is pretty much guessing at what it sees, how can we know it is telling us the truth? A three dimensional world becomes a two dimensional retinal "image" that in turn becomes a three dimensional perception. How can we be sure that anything besides our own brain really exists, if our brain is what tells us what we perceive?