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Neurobiology and Behavior, Week 9

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 begun to move into the space between neurons and behavior, the creation of new properties by interconnected neuronal circuits.   In addition to central pattern generation, we now have corollary discharge.  Does this help us make sense of behavior in terms of neurons?  In what ways?  With what limitations?


rkirloskar's picture


Snakes use their tongue to detect smell in thier environment. Would this be considered as a form of synesthesia? If it is, then I wonder if the phenomenon of synesthesia was a result of humans inheriting vestigial neural connections. There may be some more animals capable of using one sense to stimulate another and these neural connections responsible for such phenomenon may have been passed onto various species as organisms evolved over time.

JJLopez's picture


The comment below made me think about memorization in general.  I think that I have a pretty good visual memory, but I cannot memorize texts.  It amazes me how artists can remember all their work.  For instance, how on earth do theater performers remember all their lines, and can recite everything word for word?  How can singers remember all the lyrics to all their songs and perform at concerts without messing up any lyrics of the many songs they play? I'm wondering, just like piano players have a c.p.g for their piano playing skill, is each song or each play script memorized stored in a new c.p.g. or is it just part of the brain's general memory box?  How can a person develop such a large capacity for memory or how can the body recognize or remember which c.p.g to use when it comes time to perform? 

kdilliplan's picture

Getting Songs Stuck in Your Head


I’ve been wondering how and why songs can get stuck in your head. This seems to happen to me frequently. Sometimes the song is one I’ve heard recently, so it makes sense that I’m thinking about it. Other times, it’s a song I haven’t heard (or I haven’t been aware of hearing) in a long time. Does it make sense to think about songs that are stuck in someone’s head as a repeating pattern of signals that may or may not have an input trigger? It’s interesting that sometimes it’s just the tune that gets stuck, other times it’s the sound of a specific recording of a song, or a specific person’s voice singing it. I suppose this makes sense after talking about how inputs can be complex and induce behaviors and responses that are even more complex. I wonder what it is about having a song stuck in your head that makes you want (or NEED) to hum it or sing it. I also wonder why the (usually successful) cure for a song that’s stuck in your head is to listen to that song. What does that do to alter the pattern in the brain enough to break the loop? 

Are there other, similar phenomena in the nervous system? I never really think of having a sight or a smell or a feeling or a flavor stuck in my head. Scent memory (a specific scent reviving a memory out of context) is somewhat similar, except that phenomenon is generally associated with a scent input. Recurring dreams might also be similar, except I don’t usually think recurring dreams run on a loop incessantly throughout the night. 


meroberts's picture


I think that you bring up an interesting point, Kathy. Have you ever thought that maybe you remember songs because of the presence of other sensory information? Perhaps you recognize a similar place or person and think of the song. This reminded me of something I learned about in another neurobiology course. Synesthesia is a condition where someone associates inputs from multiple senses. For example, a person might think of the color red when they hear the number 6, or something crazy like that. This website explains it a lot better than I could:

Maybe the association between spontaneously recalling songs and synesthesia is way off base. But maybe you think of a song or certain song lyrics because you're reminded of it by being in a certain state of mind, or by being near someone who reminds you of the song in some way. Perhaps there are other senses at play when you remember a song (seemingly) randomly.

mleung01's picture

Phantom limb and corollary discharge

The concept of the phantom limb is fascinating but incomplete. The experiment “The Mirror Cure for Phantom Pain,” only looked at 3 groups: mirror movements, covered mirror movements and imagined movements. The conclusion from this particular experiment is that patients that watched the reflected image of their intact foot in a mirror while they moved reported a decreased in pain in their amputated leg. My question is why didn’t they put in a group for people who wore prosthetic limbs or those who have 2 amputated legs? If the results were that using mirror movements helped, wouldn’t the concept of knowing you have a prosthetic attached have the same affect? As for those who have 2 amputated legs, how would you categorize them in terms of this experiment?The idea of corollary discharge can be applied here too. If corollary discharge means a mechanism in the brain that allows one to distinguish between self-generated and external stimuli and perceptions, could it be possible that a patient just perceive they have a limb or self-generating the pain?

Another thought that I had on corollary discharge is when children pick which hand will be their dominant hand. As in many Asian cultures, the right hand is the preferred hand of choice and grandparents or parents sometimes uses force to establish the dominant hand. But, if you place the a utensil or pencil in front of the child, it will choose which hand it would like to use by itself without any external stimuli. Its an innate ability just like walking, eating and breathing.  


Saba Ashraf's picture

Corollary discharge/motion sickness

            This week during class I had also found the topic regarding corollary discharge very helpful regarding motion sickness. Many times I have attempted to read even a short piece of writing during a car ride, but my carsickness shows up shortly after. I have found sometimes though that I can read a short piece of writing during a car ride without feeling any symptoms of carsickness, yet other times I don’t even have to read much and the symptoms will appear shortly after. Also, my carsickness shows up only when reading, but doesn’t seem to show up when I’m doing some sort of puzzle. Because the nervous system experiences something that it had not expected, motion sickness arises; however, it would be interesting to find out why I only get motion sickness when concentrating on a book, but not on a puzzle. I also find it amusing how differently some individuals’ nervous systems respond to input signals regarding motion sickness. Just how others have mentioned, some individuals in my family have no issue with motion sickness, yet my mom and I get motion sickness very easily. This adds to the differences between humans because if we all responded to the same inputs the same way, humans would be that much similar. The phantom limb example used in class was also very interesting and it makes sense that one with an amputated limb would still feel it on their body despite the fact it is not there anymore and when they are able to visualize their amputated limb through a mirror, the symptoms of the syndrome decrease.   

yml's picture

Corollary Discharge

I found the discussion about the phantom limb syndrome and mirror box treatment very interesting. I have seen this in the show House, MD awhile ago and thought it was interesting. Of course, I didn’t know anything about corollary discharge and wasn’t even sure if it was made up thing for the show, or well known and recognized treatment. I also thought the pain and why the treatment works is are all because of “psychological” effect. In other words, it’s all in your head (not the head with nervous system, neurons, etc, but head as “mind”). Learning about corollary discharge taught me that the problem with phantom limb syndrome is not because one “believes” something, therefore it happens even though it’s not really there, but there really is brain chemistry that explains why brain acts that way. I don’t know what I’m saying makes sense for others, but it is kind of legitimating the syndrome.

With phantom limb syndrome and mirror box treatment, corollary discharge is used to “fool” the brain to think of the hand in the mirror as real arm and because it’s working fine, it shouldn’t hurt, therefore it doesn’t hurt. In contrast, the car sickness example used corollary discharge to correctly put the vision in accordance with the movement, therefore does not feel sick in the moving car. If I understood correctly, these two examples showed how one idea can be used in opposite ways to get rid of problems. Clever!  


cschoonover's picture

CPGs, motion sickness, and pain

 I thought our discussion last week about CPGs and corollary discharge signals was really intriguing. Mostly I found it interesting that we have an innate ability walk, eat, and keep ourselves afloat in water and that the period described as “learning to walk” is just a necessary delay for maturity. That fact that these motor patterns are built-in and allow us to do things that we may not have learned how to do is amazing and is a further testament to the sophisticated inner workings of the human body. If we are born with CPGs for specific motor patterns, does this extend beyond movement? For instance, are we born with CPGs for thinking?

From CPGs we moved to corollary discharge signals, which coordinate the CPGs and go back across the NS to the sensory side and influence how input signals are interpreted. What I found most exciting about our discussion is that our experience of the world is a function of what we are doing combined with our own state. This means it is impossible to treat any two people the same because their experiences are so different. Motion sickness is a great example of this phenomenon, as it is a mismatch between expectations of input and actual input. I have not experienced extreme cases of motion sickness, although as I have gotten older I have noticed that my predisposition for it has increased. I used to be able to read for hours in the car, watch movies, etc; but now I can only read for a short amount of time before I start to feel sick. It now makes sense to me that this is the result of the discrepancy between the expectations of my NS and what is actually occurring. The corollary discharge signals say I am not moving because I am sitting in a car. However, visual input signals convey objects (trees, other cars, buildings) streaming by the window. Therefore, my sensory input does not match my NS. If the input difference is small, the NS can easily adjust. But if the difference is large, the NS says something is terribly wrong and it has difficulty adjusting. It is puzzling that over time I have become more prone to motion sickness and I wonder what the reason for this is.

In this discussion of corollary discharge signals, we mentioned that the experience of pain can be likened to motion sickness. If I assume there are similar mechanisms involved in the sensation of pain as in motion sickness, then it must follow that the NS and the input signals do not agree and the result is pain. This seems to be a more confusing notion to explain, as I am not sure where to begin. Does the NS expect there to be a lot of sensation changes due to harm to the body, and then the input signals are different? Or is it the other way around? Do the input signals exceed the expectations of the NS? I have had quite a few injuries, due to athletics, and most have been fairly painful. It would be interesting to understand what goes on behind the scenes and what causes such a wide range of intensities of pain.

Schmeltz's picture

baby swimming

This is pretty cool - didn't know that newborns also have the ability to float on their backs.


Kwarlizzle's picture

Eureka Moments

I am getting to the point where I can rephrase the class in 'scientific terms' and so that makes the subject less abstract and more plausible for me. In Tuesday's class we talked about tne difference between necessity and sufficiency. Basically. Just because something is necessary to produce an end result does not mean it's sufficient to produce said result by itself. Just because a central pattern generator is required to produce walking does not mean the central pattern generator is sufficient by itself to produce walking. The muscles have to be strong enough...the ear has to be able to keep balance... It was a little thing, but I am immensely proud of myslef. This class goes over my head sometimes. it was a great moment to be able to restate something in my own terms!

Schmeltz's picture

CPG blockage

I think it is amazing that we are born with the innate ability to perform certain tasks and activities due to the presence of central pattern generators.  A question that comes to mind, and that we touched on during class, is to what extent the environment impacts these central pattern generators.  Specifically, I am interested in what causes CPGs to fade.  Can they ever fade?  Can they disappear completely?  Is it possible that they are still completely in tact in the nervous system, but have faded in the I-function, the part of the nervous system that you designate you.  Or maybe they have not faded in the I-function particularly, but the corollary discharge, the reporting mechanism for that particular activity or task, has faded.  We discussed that newborns have the ability to swim which is why it is recommended to parents to start swimming lessons with their kids very early on.  Yet, many parents wait until 2 or 3 or even later to put their kids in the water and at this point, the kid has lost the CPGs necessary to hold their breath under water and blow out.  Perhaps though, the child has not lost the ability, it is merely being blocked or overpowered by other CPGs corresponding to fear and anxiety.  Or they have faded just because the child has not used them; however, in the case of the baby bird experiment, the baby bird had not used its wings, yet the instant the jacket was removed the bird had total knowledge of how to fly.  Why does the young child not have total knowledge of how to swim when the CPGs necessary for swimming were present at birth?  It is clear that the environment must play some sort of role as we determined.  When I was learning how to swim I was terrified of the water.  My Mom would tell me put your face in the water and I would totally freak out.  I refused and every time I tried I was convinced I would drown even if I was in only three feet of water.  Then, one day, my Mom was completely fed up with my refusal and complaints to get in the water so she picked me up and threw me in the deep end.  I was shocked and pissed off, but I swam to the surface and to the side of the pool with no problem. That's how I learned to swim and that's how my CPGs for swimming were quickly rekindled and reactivated.  I remember getting to the edge of the pool and crying because I thought what she did was cruel, but I was also thinking, now that wasn't so bad.  It makes you wonder what other CPGs we have that our minds are continually blocking due to emotions and environmental factors.  Climbing, for example, is always blowing my mind.  I know that my body has all the necessary tools to land certain moves, but doing that move at 3,000+ feet can throw one off.  I remember this one mantel I was trying push up over and I kept falling and falling and the rope kept rubbing up on the edge of the mantel.  I knew the rope would be okay from a logical point of view, but the fact that I was hanging off a rock 2000 feet above the ground with a belayer 70 feet above me that couldn't see me freaked me out to the point where I became frozen and forgot everything.  I think becoming scared and hesitant impedes the functioning of certain CPGs.  Eventually I had to get over it and just do it.  I had to just detach myself and my fears from the situation - kind of like detaching the I-function because it was the I-function that was screwing up the corollary discharges I needed to coordinate that movement to power myself over the rock.  I guess this suggests that your experience of things is a function of not only sensory input and CPGs, but also your own state of mind.  I think that your state of mind can cloud your ability to activate certain CPGs.  Now, I understand why some climbers prefer a beer or two before they power up a rock...  

Serendip Visitor's picture


I have a project I think u will be interested in

Colette's picture

To generate a central pattern

To generate a central pattern the behavior patterned has to occur or at the very least as if it had occurred.  Repeating the behavior strengthens retention of the pattern.  Neurons carry out the behavior and the sequential activation of the neurons is retained as the pattern.  Central Pattern Generation is not exclusive to actually carrying out the behavior.  The neurons which would have carried out a behavior can be patterned even if they do not carry out the behavior so long as they and the pattern are identified.  This may relate to musicians preparing music to be performed when they study the music to be performed without actually performing the music in order to prepare themselves to play a composition.  Central Pattern Generations appear to be coordinated by corollary discharges. 

kgould's picture

 In Oliver Sack's book, An

 In Oliver Sack's book, An Anthropologist on Mars, he writes of many different cases that he has looked into, but the one that came to mind while we had class on Tuesday was "A Surgeon's Life." It details the case of a surgeon and amateur pilot with Tourette's syndrome. 

I know, it sounds absurd and terrifying at first, like something Kurt Vonnegut would write about. A surgeon with Tourette's? No thanks.

But the thing is, once Dr Carl Bennet (the surgeon) starts surgery, his tics disappear. While cutting, snipping, and sewing, he shoes no signs of Tourette's.

At home, Dr Bennet is at times compelled to poke at a brick wall up to 500 times, all at once. The wall is pock marked and worn. The fridge is dented and bent-- he throws frying pans and pots at it. He can't study in the living room because he has to poke the lamp next to his chair. 

But when he is in the OR, sterilized and ready to remove a cancerous tumor from a woman's breast, he is fluid, graceful, and quick. 

I've tried to wonder what roles CPGs play in all of this, but I am not familiar enough with Tourette's to draw any conclusions.

Any ideas?

natmackow's picture

I’m reading this book for the

I’m reading this book for the book review! I can’t put it down; I’m completely hooked.

In the operating room, his tics increased, he darted, reached, lunged, moved to touch someone’s unsterile shoulder, but never quite did. As soon as he began the surgery, he was focused, smooth, unhindered by tics. He lost the identity of a Tourettic, and took on the persona of a confident, brilliant surgeon.

Perhaps his ability to almost ignore or forget about his need to tic while performing surgery has something to do with CPGs and the I-function? Perhaps this is related to a pianist focusing and letting their brain and fingers play the song, and not actually thinking about their actions, lest they lose their rhythm? Because Sacks mentions that when Bennett was distracted multiple times during surgery with outside demands, his concentration would break, he would remember that he was Tourettic, and his smooth rhythm would be lost (which was why he wasn't allowed to be distracted).

AndyMittelman's picture

    I am particularly

    I am particularly interested in our discussion of innate abilities that people/animals are born with. On Tuesday, we talked about how we are born with (and then fine-tune) certain CPGs that allow us to accomplish evolutionarily-important things. Just as we don't need to learn how to eat, we innately can flounder in water to keep ourselves afloat, and Jed knows how to fall off the couch. I remember a video that someone once sent me (the video was a joke), that explained that cats can fall from large heights (30-100 feet) but rarely survive short falls (10-30 feet) because they innately know how to "right" themselves...the implication was that it took the cats 3 stories to successfully flip over to land on their feet. Unfortunately I could not find the video to post for you all, but i did find this (which disproves that theory):

 It's a pretty interesting video to watch. The cat is dropping but knows instinctively (because of the CPG) to right itself before it hits the ground. We've been talking about how our nervous system takes inputs from our senses and can use those in conjunction with pre-scripted patterns to generate future outputs. This makes me wonder: if you took a cat, blindfolded it (so it could not visually tell which way was up or down), then threw it up in the air, I wonder if it would orient itself upside down? So the cat appears to have a CPG that tells it: Wow, I'm suddenly falling, I need to right myself before I hit the ground. I'm guessing that blind cats also have this pattern engrained in them as well. This would suggest that the cat doesn't see the environment wooshing by (and the floor approaching), but rather senses the fall due to the acceleration. So, back to the idea of throwing the cat upwards...if it senses acceleration and then orients itself to absorb the impact, I hypothesize that the cat would orient itself upside-down when you throw it upwards. (as a side note, the physics part of me thinks that you would have to be accelerating the cat at a constant upwards rate of 2g, such that the cat would have the same perception as that of gravity normally has on you downwards). An interesting thought experiment to think about, nonetheless.

    So if we have these CPGs, and we're creating (and modifying) CPGs all the time, then what else can we do that we don't know about? Presumably, evolution has endowed us with life-saving instincts, so I would imagine that many of these patterns would emerge in their appropriate critical moment. Just as we know to duck when something is coming at us (as pointed out by the IMAX story), then we must also have other abilities engrained in us. Any ideas?

mcchen's picture

Corollary discharge signals and motion sickness/movies in 3D

 I found our discussion on motion sickness and corollary discharge rather interesting because I have always wondered why some people get motion sickness and others don't.  Are the nervous systems of some people just better at realizing that even though the person is not moving, the car is?  My mom does not get motion sickness at all, she can be crocheting or reading a fine print book in the car and be perfectly fine.  My brother, on the other hand, cannot read or do anything else in the car other than sleep.  So does this mean my mom's nervous system is better at blocking out the unexpected signals received while sitting in a car?  Does that make her nervous system faulty? Since our bodies rely on pain to tell us something is wrong, would not having motion sickness mean that even when what the nervous system expects and the actual signals received do not match, the body can accept that?

Corollary discharge signals can also be applied to watching movies in IMAX/3D.  I saw a move in IMAX/3D this weekend and it definitely got me thinking about the actual signals we receive versus what is actually there.  So even though the movie was technically in 2D, due to visual effects, the images virtually came to life.  What I found interesting was that when an object was being thrown at a character, most people in the audience ducked.  It is instinctual to avoid objects that are coming at your head, but we were all sitting in a movie theater, we all knew that the screen could not actually harm us, and yet most of us still flinched.  I have a friend that cannot even watch movies in 3D because she gets headaches from it.  I guess watching 3D movies can be interpreted as a type of motion sickness because our nervous system is expecting a movie on a large screen but in 2D while the actual signals being interpreted are of 3D figures coming out of the screen.  


An interesting article on Phantom limb for anyone who's interested:

natmackow's picture

Motion sickness and the NS

Our discussion this past week of the communication between corollary discharge signals and sensory neurons was interesting and allowed me to understand a bit about motion sickness (something about which I’ve always been curious). The idea that discomfort as a passenger of a vehicle is, in part, due to a difference in what the nervous system expects (I’m sitting still and my NS, or corollary discharge signals, expect signals from sensory neurons to agree with this) and the actual signals received (unexpected input signals of motion from sensory neurons) makes sense to me.

I don’t generally get carsick, unless the traffic is stop and go, and I’m reading. Looking out a window in a moving vehicle doesn’t bother me, and perhaps now this can be explained as my nervous system adapting to this kind of input. Or, is my nervous system innately better able to adjust to these discrepancies between expected inputs and actual inputs? For example, my father never seems to get carsick and can go on any manner of theme park ride without physical consequences. This could be explained by the fact that his NS learned to deal with these inputs over time but for the fact that my mother’s NS has never “learned” to adjust to those motion signals. While she perhaps is not as prone to carsickness as she was as a child, she is still more likely to be affected by these differenced between expectation of input and actual input. How much of our ability to adjust to these differences is inborn, and how much is learned through experience? What causes one person to become more ill than another given similar sensory input?

I do get motion sickness when I distract my NS by reading in a car in traffic. The words in front of me bounce up and down, the car jerks suddenly (it’s movements are unpredictable to me and I am not in control of the braking), and I lose my place on the page. I get dizzy, nauseas, and develop a headache. Maybe this can be explained by my NS not being able to anticipate such choppy movement and adjust in its processing of words when they are not still. In fact, anytime an image in front of me changes or moves when I, or my NS, do not expect it (I have trouble watching movies in cars as well), I feel ill. Perhaps when I am looking out of the window of the car, my NS is able to use visual sensory inputs to better adjust to the unexpected movement. When I read, my vision is focused on something else, and without the help of these visual sensory neurons, it is possible that my NS is more unable to adjust. Finally, perhaps, when I’m reading, but the car is moving smoothly, my NS is less dependent upon visual cues and can better adjust (as I do not feel sick in these situations)?

aeraeber's picture

Corollary Discharge and Reality

Corollary discharge helps explain why neurons are connected in such complex patterns and how their communication creates behavior that is not exactly the same each time. If central pattern generators didn’t communicate with one another, they wouldn’t be all that useful, because they wouldn’t be able to adapt to changing circumstances. It also brings “thinking” into the equation, since internal actions affect outputs through corollary discharge. This leaves me wondering why some behaviors involve a connection to the I-Function and others don’t.  How does the I-Function seem to “get in the way” of patterns to which it isn’t connected, like riding a bicycle? How easy (or difficult) is to create new lines of communication between patterns? How do patterns and the lines of communication between them actually form?

On Tuesday we talked about the fact that everyone has difference experiences based on the same input signals, and that any single experience can never be the same for two people. In my opinion this gives more evidence for the idea that every one inhabits there our reality, their our universe, but that those realities must be similar to some degree, since it’s not the inputs that are different, just the internal signals that we use to interpret them. It’s sort of a frightening thought, that we (humans in general) don’t really have a common reference point of experience. No one will really ever understand what another person is experiencing, especially in terms of emotion. I suppose that’s why it’s so difficult to predict what any one person will do when presented with a difficult situation. On another note, if these internal signals were connected to the I-Function, would it then be possible to consciously change what we perceive as reality to some degree? We can change the input we are receiving, but maybe we can change how we experience it, effectively changing our reality and not anyone else’s.


Lauren McD's picture

Answered Questions

In last week's forum, I questioned the idea of babies having the innate ability to walk and not learning to walk. This week's discussion helped clear my confusion with this counterintuitive idea. Babies are born with the central pattern generator to walk, but they are not born with the abilities to balance, use certain muscles, etc that are necessary for walking. So in a way, learning and maturation are linked into the walking process, making walking an accessed ability. My question of whether or not baby birds would be able to fly if they didn't witness other birds flying was also answered. While specific experiments have not yet been conducted, it is expected that they would still be able to fly. The discussion in class this week helped answer my questions from last week, while also introducing new ideas. I found the phantom limb discussion intriguing, and wonder how anyone could have first thought of its therapy. The discomfort felt is a misalignment of expectations and actual input. This helps explain many common symptoms such as motion sickness, and I'm curious about what other discomforts it can help explain. I appreciate how we are now bridging the gap between neurons and behavior.

MEL's picture

CPGs and Corollary Discharge

I think that corollary discharge and central pattern generation help us make sense of behavior in terms of neurons. Corollary discharge and central pattern generation make it easier for me to understand how we perform common daily activities so easily and effortlessly. I found our class discussion about phantom limb syndrome very interesting. It does make sense that the central pattern generator for a limb remains even after a limb has been amputated. If phantom limb is due to the non-correspondence between sensory input and corollary discharge, is there any way to stop or decrease the pain? After a substantial amount of time, will the limb’s central pattern generator stop working due to disuse?   I also found our discussion about motion sickness very interesting. I have noticed that I get car sick when I am in the backseat of a car but never when I am driving.  This also makes sense in the terms that is due to the non-correspondence between sensory input and corollary discharge


molivares's picture


I was completely fascinated by the article Mind Over Body: Stroke victims cannot perceive paralysis in themselves--or others in Scientific American. This notion that, “Some anosognosics not only are unaware of their own paralysis, they are also unable to perceive paralysis in others. This finding seems to indicate that our awareness of ourselves is inextricably entwined with our awareness of others” is something that I’m having trouble understanding in terms of corollary discharge. If corollary discharge is a mechanism in the brain that allows one to distinguish between self-generated and external stimuli or perceptions then what role does it play in the awareness of others in the case of anosognosics? I guess I’m just having trouble applying this neurobiological concept to a case that involves not just a self-awareness but an awareness apart from ourselves. This articles certainly does add, “a new twist on the old mind-body problem; our bodies are, in a sense, self-projected constructs, an integral part of our minds” – a concept that brings us back to the beginning of the semester in talking about Dickinson’s and Descartes stories on the brain and behavior.

emily's picture

corollary discharge

 Corollary discharge has helped me better understand vision and hallucinations. In my first web paper a Revision of Vision, I wrote about vision as a function of the brain, that what we see has to do with what neurons are active (whether due to outside stimuli or processes within the brain). However, I had no background to say what specifically would cause the brain to activate its own neurons. This week we learned that CPGs interact across the NS with sensory input, influencing how that input is interpreted. The brain's own "outputs" altering how our sensory inputs are translated supports my claims, that what we see has just as much to do with what our eyes tell us (sensory input) as what our brains tell us (CPGs/corollary discharge). Corollary discharge helps us make sense of behavior in terms of the neurons because it shows how connected all the neurons are to each other; they can "check" each other. 

mcurrie's picture

Pain and Corollary Discharge

As we talked about corollary discharge and its connection to phantom limb and feeling pain in their nonexistent limb I was thinking about pain. Like when you get a cut or some child scrapes their knee and doesn't feel the pain. But when someone points out they have a cut and the person looks down then the cut starts to hurt and with children they have the sudden reaction to cry. Why when we get the cut is there no pain? I can understand that when looking at a cut the corollary discharge would tell the body that is it hurt and that the body should feel pain and so you then experience pain. But what about before looking at the cut? What is blocking the feeling of pain? You could also see this when children fall and parents make a face. Sometimes the kid is fine and as long as their parents don't make a sad or weird face the kid laughs and goes on with playing. But when someone makes a face and asks the child if their fine they start crying knowing that they should be hurt. Is this corollary discharge of placing a certain face and voice to being hurt and so tell the child their hurt and should start crying? Then this still opens the question of what is pain? What makes us feel pain? Is it corollary discharge, a central pattern, something else or a complex of patterns, neurons, chemicals? 

Jeanette Bates's picture

phantom limbs and carsickness

             I think that corollary discharge has helped me understand a lot of natural phenomena. For example, I get carsick rather easily, especially on the blue bus, and my friend has always told me that I should look out the window when I get carsick.  Whenever I do, I start to feel better. I now recognize that my body happens to be very sensitive to conflicting signals. My inner ear is telling me that I’m moving, but when I’m reading or even just looking at the head in front of me, my eye’s sensory neurons are telling me that I’m not moving.  When I look out the window, however, I see movement, and so the conflict goes away.

            Corollary discharge also helps me make sense of why the mirror treatment works on people with phantom limb syndrome. If someone’s eyes see that there is no limb moving, even when that person thinks that he or she is moving it, then that person’s body will come to realize that there is no limb to move and the pain that that person feels will decrease. This makes me wonder about how much pain a person with a prosthetic limb would feel. If the sensory neurons see that there is a limb, does that information trick the brain into thinking that there is a limb? And if it does, would this decrease pain because it would cause the brain to think that the signals for movement are successfully getting through? 

gloudon's picture

stuck on central pattern generators...

 So, I am aware that we have moved on to corollary discharge, but I have one more CPG question left.  Does each innate skill get its own CPG? Or, can multiple, similar things be stored in one central pattern generator.  If you think about memorizing pieces of music, to the point where your I-function conflicts with your CPG's ability for you to play the piece of music without thinking, does it create and get stored in one big CPG file in your brain?  To me, it would make sense to have a music CPG that stored all of the pieces, or to have one CPG for each piece of music that you memorized.  Further, if you play multiple multiple instruments and or read multiple musical clefts, are they stored in the big music CPG or do they each have their own CPG?  If they are separate CPG's, does each subsequent CPG become easier to form?