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Neurobiology and Behavior, Week 13

Paul Grobstein's picture

Welcome to the on-line forum associated with the Biology 202 at Bryn Mawr College. Its a way to keep conversations going between course meetings, and to do so in a way that makes our conversations available to other who may in turn have interesting thoughts to contribute to them. Leave whatever thoughts in progress you think might be useful to others, see what other people are thinking, and add thoughts that that in turn generates in you.

You're free to write about whatever came into your mind this week, but if you need something to get you started ... We've finished a survey of vision and ended up in something of the same place we did with movement, distributed systems, constructions and a distinction between unconscious processing and an I-function responsible for what we're aware of, for "stories."  What are you reactions to this?  Can we use it to make sense of other aspects of brain and behavior?


sophie b.'s picture

 I found it more than a

 I found it more than a little bit disconcerting that sight is not fact, but rather our mind's interpretation of the world, especially since sight is generally perceived to be absolute fact (except for during hallucinations or mental illness, like the case of John Nash) . It seems sort of contradictory to everything that we learn about visual images as children. However, after thinking about it, sight as the brain's interpretation of our surroundings actually makes perfect sense. 
People have different tastes in what they find aesthetically pleasing, even though the actual objects (or people) that we are viewing are the same. It seems that while we often think of sight as something that cannot be manipulated by our minds, however the vast differences in taste suggest that sight is in fact, subject to interpretation by the brain. 

Colette's picture

  When discussing the movie


When discussing the movie "Beautiful Mind" about the schizophrenic John Nash, it made me wonder--aren't we all a little schizophrenic? Like Nash, we see so many things that look real but in actuality are not. For example, when we looked at the checker board and we thought some of the colors were different, but when put under the right type of light, they were actually the same color. There can be much variation in the accuracy of sensory perceptions. Many animals have much more sensitive and accurate senses than humans, for example bloodhounds for smell and eagles for vision. Compounding the problem is the interpretation of sensory signals done by the brain is not perfectly accurate. What passes for real may only be an approximation. Inaccuracies are not diseases, but limitations. When the source is unknown it might be difficult knowing if a person is speaking in the next room or the DVD. The defect in distinguishing what is real in disease states like schizophrenia usually goes beyond figuring out that the TV is not a real live person.

natmackow's picture

Perspective cues "fool" the NS

I found our discussion of the experience of the picture in the head to be pretty interesting. I was especially intrigued by the cues that artists utilize to create a sense of depth for their audience. Artists seem to achieve a greater sense of depth through these cues, while photographers, in directly copying a 3-dimensional world, create 2-dimensional images. Somehow, the human nervous system can be momentarily fooled by a painting in thinking that its images extend out into our world, while a photograph appears merely as a 2D representation of something. What is going on in the brain that causes this discrepancy of interpretation?

Images of sidewalk artists’ uses of perspective cues: One, Two, Three

Despite this, the NS still perceives an element of depth in photographs, and the intensity of this perception is dependent on how the photograph was taken. Photographers often use perspective visual cues, much like painters do (large objects are closer to the individual taking the picture, parallel lines converge toward a point, etc.). These cues allow a viewer of an image to “see” the object in question as if it were actually in front of them. This use of perspective can also be used to “fool” the nervous system into interpreting an image differently than they would with a slightly different perspective (as in the case of our leopard photo). The following images are examples of this: Four, Five, Six, Seven

Our ability to “see” how we perceive and interpret visual inputs allows photographers and painters to manipulate these cues to make their audience see what they want them to see. Despite our “i-function” knowledge that our initial interpretation of these images cannot possibly be real, our NS still believes the story until given further input. This seems to suggest that the NS’s interpretation of visual, auditory, and other sensory inputs override any such knowledge the “i-function” has about what is being sensed. How involved is the “i-function” in seeing these images? Is the “i-function” only involved in the experience of a sensation or is this mystery more complex?

kdilliplan's picture

Finite Ambiguity

I’ve been thinking about how people often see what they want to see and don’t see what they don’t want to see.  From they way we’ve been talking about vision, the I-function and stories in class, it would be easy to say “we’ll never truly know what ‘reality’ is because everything we perceive is only a story in our heads” and be done with it. I don’t think that is a useful thing to do. There seems to be a large amount of standardization in the way people see things. For instance, in the case of the ambiguous images we looked at in class, there were four main responses: 1) It’s a woman standing by a tree with buildings, etc. in the background. 2) It’s a face.  3) It’s both a woman by a tree and a face, depending on how you look at it.  4) It’s neither a woman nor a face, only a pattern of light and dark. However, very few people would look at the image and see something other than one of those four options. Very few people would see a space ship, or the inside of a library, or a basket of fruit, no matter how much they wanted to. The same goes for all the ambiguous images we looked at.  We can make several different stories about what we see, but we can’t really make an infinite number of plausible stories.  This leads me to believe that there is some degree of “truth” to the images, or at least we are all similarly limited in what we are able to perceive.

meroberts's picture

Making do with the I-function

The more we learn about the I-function and its role in shaping our images and perceptions, the more confused I am about its purpose. It limits the sensory input received by the brain and it distorts our perception of reality. Yet, there must be some reason for it since we (presumably) all have an I-function. I understand that it limits the amount of information that the brain has to process and respond to, but I don't understand the underlying process of filtration. Why is it that some input is indeed interpreted by the brain but other sensory information is discarded? Is the same type of input discarded consistently or is it a random process? Moreover, what type of information am I missing because my brain can't, or won't, process the information?

cschoonover's picture

Filling the Gaps

 The fact that the picture in our head is the result of a conglomerate of interconnected pathways, a pattern of activity across a number of neurons makes sense, especially in relation to creativity. I think the world would be an incredibly boring place if we all saw the world in the same way. Like we talked about in class, some of the greatest technological advances have been the result of creating a picture or story in one’s head of something that has never been seen before. Without this ability it might take ten times as long for the world to benefit from inventions such as the airplane or computer. Both of those were novel inventions, not simply updates of previously existing objects. Part of the excitement that accompanies the world of science is the ability to imagine a solution and then determine if it can be put into practice.  In my last web paper I wrote about the world of bionics, and specifically bionic arms. Before the first one was constructed no one ever thought that after an amputation they would ever use that limb again. And with what was probably considered to be an “outrageous” idea, amputees were given the chance to live more normally. The first prosthetic was realized via a picture in the head and made possible due to the notion that, because this picture is simply the brain’s best guess, the best guess allows us to bring into existence things that aren’t actually there.  

A large part of our “perception” of the world involves experiencing what we sense. It was interesting to determine, in class, that the picture in the head is being reported to the I-function and that the experience of the world can change without a functional I-function. In class we said that without the visual cortex you can see things, in the sense that you can respond to them, but you can’t experience seeing them. This is a strange phenomenon to imagine because so much of my understanding of the world involves experience, and making decisions and “guesses” about the world based on previous experiences. If this is true for the visual system, then it seems to me that it would apply to the other sense systems as well, maybe most particularly the auditory system. Does this apply to the other sensory systems? What about our sense of touch? How much of what we feel is just our brain creating a story? 

Congwen Wang's picture

Back to I-function

After spending several weeks talking about how our other parts of the brain trick our I-function, we come back to the more I-function related dicussion this time, it seems. I'm really interested in the case study about patients with visual field deficits. So, they can't see things with certain part of the retina because their I-function fails to acknowledge some of the brain activities, but they can still point out the direction of the light quite accurately because the other boxes in their brain are still working. This result is very intersting, and it actually confuses me. I always think pointing the direction with our hands mainly involves our I-function, but now I'm not so sure. After all, how can those patients use their I-function to point out the light correctly, when their I-function is not even aware of the light? So maybe pointing our hand to something doesn't require the presence of I-function?

yml's picture

Tricking my eyes

I found the example of cube with just outlines, how we can see it as one way (sides as outside of the cube) and another (sides as inside of the cube) depending on how other object pass through it. Without those objects, I could still make myself to see it (wait, I’m still seeing it as same, but perceiving it differently? – it’s getting confusing!!) one way and another, alternating back and forth, but it took some effort and took awhile to change back and forth. However, with other objects passing through, transferring the thought was so much easier and more instant. And there was an example of checkerboard, from last week, where even though we know what’s the truth, we can’t change how we see it. So, now, I was wondering if the I-function for each of these examples were behaving differently.


MEL's picture

Vision and Optical Illusions


Even though I initially felt a bit uneasy about the fact that my vision is only representing a “story” of what’s out there and not actual reality, I now understand why it must do this. Without construction, we would only perceive dots and meaningless information. Although this construction sometimes causes us to see our world in impossible and incorrect ways (e.g. the impossible arch), most of the time our brains' construction enables us to function and gives us useful information about the world around us.  Also, the “story” our brains create and our sense of reality are checked by many other cues and sensory inputs. Taking all of these facts into consideration, I think that our visual system works in a very logical and efficient way.  

I also found our discussion about optical illusions this week very interesting. I think that these ambiguous pictures are very fascinating because our brains can form more than one construction. I found it very interesting that in class, when looking at the optical illusions, it took me a long time to see the other possible construction. It seems that my brain constructed one image and held on to the belief that it was the actual and only possible image. In order to see the other possible construction, I either had to really concentrate on the image or I had look away from the image for a long time and suddenly look back. I think the idea that my brain stuck to its initial interpretation really shows why and how we have such a concrete and stable view of the world.


AndyMittelman's picture

The Leopards

I keep thinking about the picture of the leopards that we looked at this week. After looking at them, I have come to the conclusion that the leopard in the foreground is looking straight ahead, and the one in the background is looking over its left shoulder. Of perhaps more importance, what is it about our visual system that allows us to perceive multiple meanings in a single image?

Whenever I see optical illusions I think of elementary school when we used to look at optical illusions in art class. I distinctly remember heated arguments about what the pictures displayed. Each one of us saw an image and adamantly defended this perception as the sole interpretation. Of course, we knew that there was another meaning to the picture but it took great effort and time to get a classroom of first graders to see both sides of the optical illusion. The teacher would have to slowly and meticulously point out the aspects of each illusion. Even still, many of us struggled to easily switch between the two images.

Unfortunately throughout most of my education I have been deprived of optical illusions, until the other day. This was the first time I looked at one in a classroom setting since first grade. I was immediately struck by the dynamic visual ability of such mature adults. What is it that allows us to see both images of an optical illusion? We can switch between the images (like the animated cube), whereas previously I could only see one version without great effort.

I am guessing that as we mature, we also gain a more dynamic relationship with our sensory input. Perhaps we learn how to interpret these inputs in more complex ways. More importantly, we seem to realize that our senses should not be endowed with unquestioning faith. It is possible that our interpretation of the world is not the sole interpretation. As we cross between interpretations, we identify that our surroundings may have multiple meanings. This is a sign of maturity; we are not arguing like first graders whether the leopard is looking forward or backwards (but you should know that my interpretation shown above is the best one). Maybe this is the sign of a more experienced relationship between the i-function and the sensory inputs?

mcchen's picture

I-function and checking our stories

 When we were looking at the optical illusions in class, I found myself only seeing the image in one or two ways.  But after people started saying that they saw it another 2 different way I started looking for them.  We had discussed that our NS is constantly unconsciously checking our "stories" all the time, making sure they match up to our surroundings.  But what happens when I am consciously looking for different ways to see an optical illusion? Doesn't that mean my I-function is involved and I am consciously trying to change the story that I already see?  What I found interesting was that while I was trying to see the optical illusion differently, I had to sort of erase what I already thought I saw and start again with a clean slate.  I think the sense of "erasing" what I thought I perceived definitely had to involve the I-function in some way unless the NS does it also to prepare for other incoming input.  

Saba Ashraf's picture

Reality/optical illusions

            I also found the optical illusions very interesting during class and the illustration of different objects moving through a 3d drawing of the cube in class was a good example of the fact that the nervous system has the ability to interpret objects in different ways. I think the fact that people’s brains see and interpret things differently adds to the fact that we are all different and because of this, our “stories” of what is actually out there differ to some degree. This relates to the fact that we aren’t limited to what’s actually there because of the creativity we have and if different individuals interpret things differently, it only adds to the variation of creativity. I also agree that we constantly use cues to check our sense of reality. For example, we may not have to constantly make sure whether an individual is real or not like the example of the schizophrenic in class, but we may check to see if others found something as surprising as we do by their reactions. I often see people look to one another when something crazy or surprising has happened to “check” if others also reacted the same way. I found the discussion about the striate cortex and the loss of the ability to see everything on the left of the fovea quite interesting as well. In particular, the fact that people with this condition are able to locate where the lights are coming from was amusing, but made sense considering the picture in the head is not in the I-function.    

aeraeber's picture

Thinking About Mental Illness

It’s still a bit strange to think of what we experience as a story rather than as reality, because we treat it so much as reality, as something absolute and unambiguous. I suppose it would be difficult to deal with if we didn’t treat it as such. If our conscious brain had to make sense of all of the input we received, it would probably be entirely overwhelming and the world would be a very strange and confusing place. Still, it leaves me wondering how much of the commonality in human experience is based on learned terminology and cultural ideas and how much of it really is the same? On the other hand, it is sort of comforting to think that we are individuals, at least in the sense that we have different perceptions of the world.

The fact that there is a distinction between unconscious processing and things that we are aware, things connected to the I-function makes sense in that our behavior is not always related to our perception of the world.  Possibly this has something to do with phobias. People can never really explain why they are afraid of heights or crowded rooms or open spaces, they just are, to the point that it hinders their normal functioning. Maybe that fear is so disconnected from the I-function that it can’t be accessed by it at all. This might also help us make better sense  of mental illness. Perhaps people with schizophrenia, bipolar disorder, or severe anxiety simply have stories that are so radically different from those of other people that they cannot function well in society. Do anti-psychotics and other such medications then have some effect on the stories a person's I-function tells them? How exactly do mental illnesses affect perception anyway?


gloudon's picture

Filling in the blanks...

The concept that the brain fills in the blanks for us (with colors) is starting to really make sense to me.  This concept must save the brain a lot of time, as it doesn't have to interpret every pixel, like a camera.  Also, it probably saves our brains time in that it answers questions to prevent confusion.  For instance, if see something from far away and it appears to be covered in dots, then you just go with 'its covered in dots" unless you personally choose to question what you are really seeing.  I can't imagine how much time it would take if I needed to think about each object I saw, and question the color or pattern or texture.  To me, it seems that our brains are set up to make these assumptions and save us time from thinking about what the color or texture is to everyone else.  I know I could drive myself crazy if I looked at a shirt that was greenish blue, and debated which color it was with myself.  It always seems to me with those kinds of discrepancies that i'm not fighting with myself over the color, but I may disagree with other people as to what color the shirt really is (green or blue), because my brain made a quick one time decision about the color.   

lfrontino's picture


I was definitely interested in the idea of conflicted brain images and some of the cues artists use to "trick" the brain into thinking the flat strokes are actually 3-d. What I wonder is why photographs don't appear as 3-d images to us. I guess they do in a way, but it seems strange to be able to take a moment that is so obviously real life and 3-dimensional and be able to depict it on a flat photograph. Why doesn't our nervous system interpret this at 3-d since we know what these people actually look like in real life? 

Also, is there a certain brain wiring that causes us to see one image before another in an ambiguous figure? It seems strange that the class would be so divided as to what they saw first on the images that were displayed in class. Sometimes it took me awhile to actually see the second image; does this have to do with me as an individual? 

Our discussion on Thursday also brought up an excellent point about imagination and how this is necessary for further progressing our society in terms of technology, etc. I don't think I find it as unnerving as I should that our brains don't actually see reality precisely for the fact that because of this, it makes it possible to imagine things that could otherwise never exist.  

Lauren McD's picture


I found it really interesting this week that we looked at many optical illusions. They were always intriguing to look at as a kid, but now we have the ability to look at them and analyze the functions in our brain that relate to them. Every illusion we looked at doesn't have a true image; it is merely a pattern of lines and light. How we interpret those patterns is what creates the image in our head.

This may be slightly off topic, but our discussion of the movie 'A Beautiful Mind' was interesting as well. I can't possibly imagine attempting to ignore something that I thought was reality. Is there any possibility that schizophrenic patients can actually find the will power to ignore their hallucinations? It's an interesting thought that patients with schizophrenia are only seeing another version, or story, of reality. And yet humanity deems them 'crazy.' In class, we discussed how we can never truly know what's out there because we can only see it through human eyes. If there are different 'stories' of reality, who decides where to draw the line of stories between sanity and insanity? Surely someone who is colorblind is not considered insane, but someone who has hallucinations is. Isn't everyone's reality slightly different? Perhaps our conception of insanity is a story so different that it is difficult to function in everyday life.

mcurrie's picture


 With the soldiers who's neocortex's were damaged and they couldn't actually experience seeing the flashing lights but the nervous system was aware of it makes me wonder what else we are not experiencing but the body is still aware of. I figure this would be a survival mechanism, that although the person may not see or experience something the nervous system is still aware of the surroundings and can alert the organism if something is not right. Or the corollary discharge then gives a signal to the I-function for the person to then become aware of a disturbance. Is this what is going on when I zone out? Or is zoning out still the I-function. I know when I stare at a wall I am completely unaware of my surroundings, having only my thoughts or even just a blank mind. Then when there's a sound or hand waved in front of my face my nervous system jostles me out of my trance and tells me to become aware of my surroundings again.

Going back to what we first talked about in how everyone sees things differently, and if they look at an ambiguous figure some will see the same image while others will see another. I would still like to perform the experiment to account for all five senses and see how a person describes what they see, hear, feel is similar and different, like putting people into a room with a music box that doesn't exactly look like one but is playing music. I think it would be interesting to compare the descriptions, see what words people use.

molivares's picture

More on hearing and filling in gaps

This spring break, I was in Turkey with the Bryn Mawr and Haverford Chamber Singers and we had spent the entire semester learning about Turkish music which is closely tied to Arabic music . One of the things that struck me most about Turkish music were the nine in-between tones between notes.  I learned that some of the most talented Turkish singers could pin point and sing all nine of the in-between tones. This really impressed me because in Western music, we really only distinguish between semitones/half-tones (C and C# or B and Bflat).  When I listened to examples of the 9 in-between tones that were distinguishable in Turkish music, I was hardly able to tell the differences between them. I suppose that this was an example of my brain filling in what I was hearing to a scheme of notes and tones that I had learned and was familiar with.  What then can be said about the relationship of the brain filling in gaps (in hearing) and the learning through a certain schemas?

Jeanette Bates's picture

Filling in the gaps

I think that it is very interesting that the brain can see without seeing or that it can “lie” to us, telling us that we see things that aren’t actually there.  Since the brain is a tightly connected network, it makes sense to me that there are some parallels between how the visual system and motor system work, especially in relationship to the I-function. In other words, I am not surprised that people can see without consciously seeing anything because there are people that can move without being able to consciously move anything. What I am most curious about at this point is how what we have learned about how these things may relate to other systems. For example, we have learned that our brain “lies” to us about seeing and hearing by filling in the gaps of our vision or gaps in the words that we hear. Does this apply to smelling, tasting, and feeling? What I mean is, can it possible that we aren’t completely feeling something, or we aren’t feeling all of it, but our brain decides to fill in the gaps and lie to us about the way we are feeling something?  

emily's picture

Vision --> I function --> Intuition

I thought the most interesting point of discussion this past week was when we talked about the patients with damage to their neocortices who were unable to "see" the lights flashed on the screen, but were able to point to them with a fair degree of accuracy. This is because the visual information was not getting to the I function even though it was getting to the NS by means of the retina. In light of our past discussions about the I function, this makes total sense. Our "story" of the world depends on what we are aware of: if we are not aware of anything (visual information does not get to I function), then there can be no experience. This implies that what we see, what we sense, what we are is a function of the brain, and ultimately depend on a small fraction of the neurons (the I function). But, this also implies that there might be so much more going on in the world that we do not even realize, that have no connection to our I function. Things we can respond to, but we cannot experience, like pointing to lights we cannot see. Intuition, gut feelings? I wonder how the I function relates to intuition. We experience a sense of insistence, and often we do not know where this feeling comes from, or, we point to this feeling that we often cannot make sense of.