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An ongoing conversation on brain and behavior, associated with Biology 202, spring, 1999, at Bryn Mawr College. Student responses to weekly lecture/discussions. A suggested topic was provided, but students were free to write about any other observations, ideas, or questions that particularly interested them.
We ran into the "I-function" again, in talking about effects of damage to the motor cortex (earlier from talking about quadriplegics). And we'll run into again later in the course. For now, how well-defined and/or useful is this idea? In thinking about the nervous system? In thinking about behavior? Is it something we have to think about? Can one imagine it in terms of neurons, or of interacting circuits of neurons?
For example, opinions. I may hold the opinion that use of animals for scientific inquiry is wrong. The ability to hold that opinion would depend on an I-funciton. I doubt, however, that it is the same I-function in the motor cortex associasted with voluntary movements. A stroke damaging my motor cortex would affect my I-function for movements but would not affect my I-function for opinions on animal research.
This presents in my mind the possiblity that the I-funcion is a neuronal circuit present in many areas of the brain. It performs the same function of creating a sense of self in each area. In the motor cortex, the sense of a self causing movement and in the opinion area a sense of self holding an opinion. I imagine having the I-fucntion spread out would also be beneficial. For if the I function were loclalized to one region and that region was destroyed by some trauma, then the person would live without a sense of being-- which is pretty maladaptive.
It is also interesting to me the point that Lacey presents relating I-fucntion to past experiences. It defintiely seems related to this part of the brain to me too. When a person gets Alhiemer's disease, they and those close to them feel that they are not like the person they used to be-- that they are not themselves. The erasure of past memories seems to erase some sense of self as well. Again this presents to me the possibility that the I-function is present in many areas of the brain and can be impaired by damage to many parts of the brain. Some sense of self is still retained after damage because the I-functions in other areas are still working.
Actually there are both negative and positive feedback loops involved in the menstrual cycle. The extent to which there are changes in the set points of these is an interesting question. As is the issue of the relation between hormone levels and mating behavior. I like your idea that, whatever that relationship, other patterns of activity can also influence whether one actually engages in mating behavior. Whether these ought to be called "corollary discharge" signals is a matter of definition. We developed that term from thinking about what additional signals pattern generators must be creating during movement and probably one doesn't need to be moving in order to make mating choices. Maybe a more general idea would be that "thinking" (like moving) involves patterns of activity (within interneurons rather than motoneurons) and this may also be accompanied by signals sent to other parts of the nervous system which influence their function? I don't know of an existing term for the latter. Shall we call it "internal signalling"? or something like that?
In addition to the suggestion that we there is an “internal signaling” which would correspond to the thought processes that might interfere with mating behavior, I was thinking about how corollary discharges cause a disequilibrium (often accompanied by a queasy feeling) when motor activity on one level does not correspond to activity on another level. While certainly one does not need to be moving on a gross motor level to make choices regarding engaging in mating behavior, I was thinking in terms of the physiological changes that occur with sexual arousal. Could we view increased blood flow, increases in respiration, increased secretions, pupil dilation and so forth, as a result of a pattern generator, and/or at least as motor activity that could cause corollary discharges as we have come to understand them?
And on a totally different topic related to neurobiology, last week I had a conversation with Professor Grobstein about a neurobiological reference in Moby Dick. I pointed out the passage that took place while ship’s carpenter was fitting Captain Ahab for a new ivory prosthesis, and the carpenter says to the captain:
"... how that a dismasted man never entirely loses the feeling of his old spar, but it will be still pricking him at times. May I humbly ask if it be really so, sir?"
And as we might expect, in light of what we have learned in class, the captain replies:
"It, is man. Look put thy live leg here in the place where mine once was; so, now, here is only one distinct leg to the eye yet two to the soul."
Professor Grobstein replied that there was another passage relevant to our upcoming studies on visual fields. I believe that the following from Moby Dick addresses that issue:
“Ahab’s boat was central; and cheering his men he told them he would
take the whale head-and-head, --- that is, pull straight up to his forehead,
--- a not uncommon thing; for when within a certain limit, such a course
excludes the coming onset from the whale’s sidelong vision.”
Interestingly, my philosophy class is right after neurobiology. It is difficult for me to “switch” my train of thought from one discussion to the next. This week in both classes we were discussing the nature of the “mind”, the I function in out terminology. Listening to the accounts of various philosophers who explain the I function without attributing any scientific foundation to their reasoning makes me rather uneasy and I begin to loose faith in their account and the rest of their theory which is often based on how they perceive the mind. The I function is thought to be something “external,” not associated with the body at all.
It is very difficult for me to write about their ideas in terms of abstract notions- I think I deal much better with circuits and chemical reactions! So in one of my papers I went on and on about evidence that brain=behavior and that the I function is a part of the brain. Of course this undermined most of the philosophical arguments which rest on the foundation of external concepts such as the spirit and the mind.
The more I learn about the nervous system the more I start believing that behavior can be explained in terms of what is going on a chemical level (neuron interactions, circuits, etc.). In my philosophy class, very often I feel that I shut my brain off, sort of speak, since I feel the discussion is not going anywhere - how could it be if the philosophers got the physiological foundations of the matter wrong? So, I have trouble defending a philosophers argument since very often I feel that I am simply bullshitting!
The question I have been wrestling with is whether or not philosophy and science can exist together....without undermining each other?
adrianne
I do think that understanding the I-function is necessary for understanding behavior. In my experience of having an I-function, being aware of myself has influenced my behavior. I sometime do very concious things. I am at times very aware of my actions, and I suspect that many people have a similar experience. Strangely, the I-function is needed to study the I-function, so the I-function can change because it is studied. Perhaps this is the power of psychoanalysis. By studying their minds, or awareness, or self, or whatever composes that illusive quality that makes us who we are, people can actually change the way that their minds work. I will have to look into this further.
Although I have trouble comprehending the I-function in neurological terms, I can't question its existence. It is very obvious is cases such as quadriplegia and hemiplegia where the ability to move still exists but the conscious decision behind the movement seems to have disappeared. In fact, the closer we look at this idea the closer we seem to get to a type of choice or "free-will". It could also possibly account for most of what people would call a "soul".
The location of this I-function is still somewhat of a mystery and probably will be for a very long time. I don't think it will be easy or maybe even possible to pinpoint it down to one location. We could begin to assume that part of the I-function is found in the motor complex by the observations from damaging that area of the brain. But the fact that this sort of damage does not destroy the entire I-function implies that there is much more to it than just that particular region. It could be that the I-function is an integration of many different parts of the brain and the motor cortex is just a part of this large integration. Or it could be that different parts of the brain account for different parts of the I-function. The motor cortex would then be the part that deals with the ability to perform certain types of movement. If this were the case, locating the I-function would be a relatively simple task of pinpointing each section. It seems more likely to me, however, that the first case is true and that there isn't a single point for each specific function. This makes the task of location infinitely more difficult.
The "I-function" as a neurobiological construction is useful in explaining behavior in neurobiological terms, though I would not be so quick to dismiss philosophy. I actually have the opposite response as Rachel Berman when I see philosophers wrestling with problems of the self. It seems that these questions have a certain amount of permanence and reveal, actually, the limits of scientific investigation. Science can give us insight into behavior and show us "functions," but it cannot show us "morality" since we cannot derive "ought" statements from "is" statements. Experience and "being" are other matters entirely, as is the idea of a "person" in the social and moral spheres. Neurobiology can tell us that a person is comatose, but it doesn't say whether a comatose individual has any rights in the legal or absolute sense. (I am thinking of issues such as living wills here.) We are still responsible for our lives, being NOT biologically determined (some of you may disagree, which is o.k. Disagreement yields philosophical discourse.) Not all philosophers are like Descartes (to whom Rachel is likely referring, right?) in drawing a distinct division between mind and body. In fact, most disagree with him. Certainly Debbie Plotnick's comments on Moby Dick suggest a role for literature in our discussions of the brain (not just from a historical standpoint, as well, although this is my addendum). I am a philosophy major, for those of you who were interested. Our investigations make for excellent first principles from which to construct an argument, but we are all f
One other thought that occurred to me was what exactly is the evolutionary purpose for the I-function. Before Thursday's class, I thought of the I-function as kind of a thinking mechanism through which we displayed choices and other thoughts. However, on Thursday, Professor Grobstein pointed out that a person's performance at a particular task is usually better when the I-function is not involved, like in the driving example. Also, while most movements can be done either voluntarily (using the I-function), or involuntarily (without the I-function), the majority of movements are involuntary. Moreover, many patterned movements (like slow, steady eye movements) can only be made by the nervous system, not the I-function. It seems to me that we have narrowed down our definition of I-function and now need to clarify its purpose. I look forward to learning more about these issues in the future.
I found an article in the journal called Nature that discusses a relevant topic to last Thursday's lecture and in the upcoming week. On Thursday we started to talk about the role of the eye in the input side of the nervous system "box". Apparently it has just been found that the brain has little impact on what information the retina picks up while watching moving objects. Instead, the retina itself anticipates movement. If the eye had to relay all information to the brain, we would actually see the moving object far behind where it actually is. I think this is interesting especially because it touches on our discussion on the concept of action potential and membrane permeability. I remember Prof. Grobstein saying that if action potential was actually a current of some kind, that it would move too fast for behavior to be really exhibited. The membrane permeability change instead takes time, moving about 1 m/s. It seems that here is an example in which the eye bypasses interaction with the brain because neural signals move too slowly. It wouldn't be surprising to me if other sensory organs totally bypass interaction with the brain. In this way too, the I-function isn't involved, and everything is a lot faster.
In addition, the processes which we identify with the I-function are those which are commonly difficult to attribute to neuronal processes. So talking about the I-function in terms of neurons seems somewhat troublesome to me. While it makes sense to attribute voluntary motor movement to the motor cortex, it is still much more difficult to attribute “sense of self,” “choice,” etc. to a specific area of the brain or to a particular circuit of neurons. While I do think that all of these aspects of the I-function can ultimately be attributed to neuronal processes, the term (once again) seems to oversimplify the issue. Although I can hardly begin to speculate about the neurobiological basis of these processes, I would tend to think that they must be much more complex than the single term would lead us to believe. For example, I don’t think that damage to a specific area of the brain or a particular neuronal pathway would result in a deficit to the I-function in the same way that damage the motor cortex results in a deficit in the ability to make voluntary motor movements. It seems that the neuronal processes which underlie the I-function must be present in many, if not all, areas of the brain.
I had a major problem with the whole "cat straightening its leg in order to defy gravity" thing. Wouldn't it seem just as logical for a cat to bend its leg up like a person bends at his elbow? Or in the person's case, couldn't they just as easily raise their arm up straight to "defy gravity". I guess I had a problem with those specific words being used, and I don't think they are valid. I understand the concept of why the leg would bend up, just not the arguement for the differences among the animals that were used as an example.
It seemed very logical in class on Thursday to demonstrate that at least some part of the I-function does lie in the motor cortex. I think it will be (or is) impossible to find a single location for the I-function. It seems that there may be bits here and there as needed or used by various portions of the brain which control outputs and are involved in signal processing. It seems that we are increasingly setting ourselves up to NOT be able to think of oursleves as having a soul but as more a function of our biology.
In class we have basically only discussed the I-function in terms of movement. My question is, with regards to the lacrosse example, what about the choices we make on the playing field that feel equally as involuntary as the act of passing and catching? Can decision-making occur without the I-function? For example, is my quick and seemingly involuntary decision to stop guarding my opponent in order to help double-team another girl based simply upon involuntary movement (absence of I-function) or involuntary thought-processes? Is there such a thing as a decision-making process which is without I-function? Is there a significant difference in the neuronal firing patterns when I am passing and catching as opposed to when I am making a choice to double-team, even though the decision seems involuntary??
I also have a question regarding the I-function in terms of sight. I was talking with a friend the other day about a phenomenon which I think is called "blind sight". This occurs when we "see" something in our visual field yet we are not really consciously aware of it. The example my friend gave is when someone is driving a car and swerves in order to avoid hitting something in the road, yet later has no recollection of having seen that object in the road. There was actually something there and the reaction is involuntary movement. So, how do we explain this? Are there different interpretations of the visual world according to the I-function, just like there are different types of movement (involuntary, voluntary, etc) according to presence or absence of the I-function? We have just begun our study of the visual system, so perhaps this is something we may discuss later? Perhaps this could be given as an example that the I-function cannot be found in one localized area of the nervous system, but rather it extends to every locus of behavior formation??
From the discussion, too, especially about people whose limbs are frozen, I began to wonder if the three types have very different kinds of firing in the brain, and that the I-function might require the most firing. It would make sense that once the CPG's have a set pattern for daily activities, the firing to execute those activities is minimal. Reflex, too, is obviously something that occurrs in bursts without effort. The I-function, however, is probably the one that shows the most functioning of neuron firing in the brain.
Essentially, the I-function is the most important part of the brain in the sense that, it seems to me, it can explain the most complex functioning of the human brain. If anything, this I-function might also be what people think of as soul, since this is the part that has original thoughts, ideas and processing.
Kim B
In thinking more about the I-function, I became very interested in trying to relate dreaming to the I function. From all of my experiences with dreaming, I would say that for the most part, my I-function is not involved (if it means consciously dictating the content of my dreams). My dreams aren't even remembered by my conscious 'mind' once I wake up. But if this is so, then what actually contributes to the phenomena of dreaming? I thought, for one moment, that the process of dreaming may be associated to CPGs. Perhaps there are actually entrenched pattern generators which are involved in the emotional and cognitive interpretation of certain visual and auditory stimuli. Just as it had been mentioned previously with the scenario of pulling over to the side of the road when red flashing lights are spotted in the rear view mirror-the red flashing lights do not illicit the behavior of pulling over due to a conscious attempt to interpret and act on the visual stimulus…the entire process is so 'automatic' that it does not involve the I-function. Perhaps it involves the pattern generator(s) created for a chain of events starting with the coding of the visual input.
In some cases, it seems that the body can recognize certain visual stimuli even before the conscious mind has a chance to fully process the image. I seem to remember certain experiments where in certain individuals with brain damage, an image presented to the left visual field may produce an autonomic response, but it is only the image presented the right visual field which is consciously assimilated by the patient. If you ask the patient what image they had seen in the left visual field (or whether or not they had actually seen anything) they will say that they did not see anything other than what was presented to the right visual field. So could it be that certain CPGs are activated in the dream state which cause automatic cognitive and emotional responses related to the input, which in turn causes the brain to create the images internally so as to relieve the issue of cognitive dissonance? In other words, perhaps these pattern generators which cause emotional responses and cognitive interpretations for visual and auditory (or other) inputs are activated randomly (or uninhibited randomly) during the dream state. In order to reconcile the fact that there are no inputs actually being received from the external world to activate the CPG's, the brain is forced to produce its own visual/auditory etc imagery to compensate or substitute? This is a strange thought…I do not know if this makes any sense in possibly explaining this phenomenon…
I think that relating the idea of choice to neuronal connections and pattern generators has a lot of potential, although we may never understand it at the level of consciousness. A simple choice can be explained by this theory—external input stimulates sensory neurons which activate pattern generators and cause a certain behavior. Add a couple branches coming off of the sensory neuron and the pattern generator and we have the basis for choice. While this may seem to oversimplify our idea of choice (including deciding where to sit on the bus) remember that one one neuron may synapse with over 500,000 other neurons. This is a system of such complexity that we cannot understand the implications of such a network. I would suggest reading the article in the NY Times "Mindless Creatures Acting Mindfully" This article demonstrates how a collection of bodies which turn on and off according to simple interactions with their adjacent neighbors can form complex and varied patterns. The units form a cohesive network even though they only communicate directly with their neighbors. This model can be applied directly to the brain. While neurons do not "think," the interaction of billions of neurons generate complex patterns in the brain which react to external input. Hence neurons are able to form complex structures which we like to say "cause" certain behaviors.
The "I" function involves thinking and choice. Humans believe that we have a more developed I function than other animals. I attended a lecture last semester which talked about different psychological models of thinking among the species. It often appears that certain species of monkeys are capable of complex problem solving, seeming to demonstrate an ability to "think." However, under controlled experimental conditions it has been determined that these species actually employ a series of trial and error attempts which eventually lead to a solution. Humans, on the other hand, are able to examine a problem, think out a solution carefully and logically and usually apply it rather successfully. While this lecture did not go into the neurobiology of such psychological models, I think that they help us understand our concept of choice and thought. A monkey is not able to make the logical, rational cognitive associations which humans employ when thinking out a problem. This discrepancy could lie in the connections between neurons and pattern generators activating such behavior. Presented with a novel problem, a monkey will activate various pattern generators until it happens upon one that works. It cannot make logical leaps which quicken the process. However, when a human is presented with a new problem, neurons fire and activate pattern generators which may activate related pattern generators and enable us to come up with the correct pattern generator quickly in a logical manner. These solutions will be based on past experience but applied to a new situation. Monkey’s seem unable to make the connection between a present dilemma and past, unrelated experiences which may aid in discovering a solution. It makes sense that our advanced ability to think and reason is enabled by an increased number of neuronal synapses between pattern generators. Don't logic and reason merely consist of connecting related ideas and concepts? While both monkeys and humans rely on the input --> pattern generator --> motor symphony sequence, humans have more connections which inhibit and activate related motor symphonies depending on the input and past experiences.
I think that this can be applied to just about any situation or goal in life, whether it be sports, grades,grad school, money for a car, simply getting to the weekend, etc. Life is all about that delicate balance. The old cliche rings true...practice makes perfect. If you try too hard it all goes to hell : )
Buddhist meditation and life is centered around exactly this idea of the perfect balance. They believe that ultimate discipline and practice are the keys to life and that once one starts concentrating on actually thinking then it all begins to fall apart. Buddhists believe that one should become so comfortable in "The Zone" that is is automatic nature. Over analyzation and concentration is thought to interfere with the simple goal of living and its success.
But seriously, when pondering the results of a brain exchange, procedure of the future, I'd think an important thing to think about is the how much of an effect hormones (that aren't produced in the brain) can have on behavior. That's the only thing I can think of that could alter thoughts/feelings/personality in a brain trade. For example, sex hormones like extrogen and testosterone are produced in the body, effect behavior, and are present in varying degrees in different people. Besides the hormonal issue, and the possible changes brought out by the person's reaction to their new body, personality, memory, and thoughts should be the same.
I also had a question about the spastic paralysis issue. In class we said that when the motor cortex is removed/inhibited, every animal assumes an exaggerated anti-gravity posture because the vestibular nuclei is no longer inhibited. Different animals have different anti-gravity postures. Why does the sloth retract (instead of extend) its legs? How much of its life does the sloth spend hanging upside-down? If it is upside-down often, that would explain the anti-gravity reaction. But to climb a tree, against gravity, an animal must extend its legs. Perhaps the sloth does much more hanging than climbing.
I believe that I may be wrong about this, but this is how I have now come to perceive the "I" function. I seem to think that we can divide the "I" function into different parts. The foremost is that a vast majority of what we perceive to be the "I" function is located in our brain. We have a thought, and then decide to make a choice rather to voluntarily complete some form of movement, or action. This thinking, and then decision process is what I first thought the "I" only dealt with. Now I seem to think that with each part of our body, there are separate "I" functions. I am just wondering, so this may strange, but it is just a thought. Let's take for example the knee jerk we talked about two weeks ago. We said that the knee jerk, if isolated can produce a form of movement on its own without the brain sending messages down to make it move. In this sense, then does the knee jerk movement have its own "I" function? Are there anymore actiond in which our bodies perform which we do not have to send messages to? We talked about this, and came up with body heat regulation, posture, and a few others. So, I think that the "I" function can be separated into different regions of the body. We don't always have to tell ourselves that we know what our bodies are doing. Such cases as the ones above act on their own, so they are in a sense making there own decision without us "thinking" about it. But this is only a thought,... well, I am getting tired now, so I am going to bed. Bye-Bye. Joey X.
I would like to respond to Rachel's query about Philosophy and science existing together. What occurred to me as I read her entry is this: that human beings philosophize at all is a direct consequence of this rather emphemeral thing that we are calling the I-function. In a feat of circular reasoning, it seems to me that whatever neuronal complexities may account for the sense of self, which I think includes the need to understand exactly what the "mind" is, it is precisely this neural circuitry that somehow accounts for the creative ideas that philosophers invent to grasp something that, biologically, continues to elude us. I don't think the philosophers got it wrong, but rather they are addressing a different question, and using the products of the question we are trying to answer (consciousness) in order to it. This is akin to Mary's comment of using the I-function to study the I-function. When we read a philosophical explanation of how the mind works, does it subtly alter how our minds work? This brings me back to my favorite question, that of experience (or outside influences) and how they affect the circuitry that we come with.
... it is plain that he can never see ad object which is exactly ahead, no more than he can one exactly astern. In a word, the position of the whale's eyes corresponds to that of a man's ears. You would find that you could only command some thirty degrees of sight' and about thirty more behind it. If your bitterest foe were walking straight towards you, with dagger uplifted in broad day, you would not be able to see hi, any more than if he were stealing upon you from behind. In a word, you would have two back, so to speak; but, at the same time, also, two fronts (side fronts): for what is it that makes the front of a man - what, indeed, but his eyes?
Moreover, while in most other animals that I can now think of, the eyes are so planted as imperceptibly to blend their visual power, so as to produce one picture and not two to the brain: the peculiar position of the whale's eyes, effectual divided as they are by many cubic feet of solid hear, which towers between them like a great mountain separating two lakes in valleys; this, of course, must wholly separated the impressions which each independent organ imparts. The whale, therefore, must see one distinct picture on this side, and another distinct picture on that side' while all between must be profound darkness and nothingness to him. ....
What is still perplexing to me is the whole idea of seperation from the I-function with paralysis. I don't understand why, if the I-function is involved in almost everything that you do, that simply severing one connection could sever all the communication and awareness of the I-function in an entire portion of your body. Shouldn't the I-function be present everywhere including the cortex? I would think that the body would have a backup system for when one part "goes down" like in a paralysis case.
One question I am struggling with in terms of the I-function and the brain=behavior hypothesis is the idea of love. I wrote about this before, and I still have not worked it out in my head why the I-function seems to turn off when two specific people interact and really "click." I also don't understand why the I-function can seem to turn on again the more you get to know a person, and you can dislike them because of this.
I am not sure how clear this is... I need to formulate my own definition of love and what the I-function is and is not comepletely involved in before I can make my statements any clearer.
It seems to me that we have only defined the I function as what we each understand to be the thinking part of us, we have not located and defined it, but we know when it is or is not involved by our intuitive definition of it. I don't find using the I function to be useful in thinking about the nervous system because it is confusing and not well defined to me yet, so I prefer to use other, more well-established parts of the nervous system to describe things. I do realize that we can't explain everything yet, but it is annoying to have to refer to this enigmatic "I function". In thinking about behavior it is interesting, as I said above, but it is also a bit frustrating to have a thing that we can just have faith in and use to explain things like why a quaruplegic doesn't know he can move. I am very interested now to see if we can place the I function in the nervous system and make it a more concrete entity. That would be a really good finale to the course…
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