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Remote Ready Biology Learning Activities

Remote Ready Biology Learning Activities has 50 remote-ready activities, which work for either your classroom or remote teaching.

Week 2: The nervous system has been equated with an input/output box consisting of interconnected output boxes themselves made of input/output boxes (neurons). If that is all there is, is it less or more likely that the nervous system and behavior are the same thing?


Well, one of the problems I had with Dennett was that he denied the existence of qualia by saying that they only seem to exist...but isn't that the point? How can qualia not exist if they are really defined as the sensory experiences we have...and we do have them. Their "seeming" is sufficient evidence in favor of their existence to allow us to refer to them. We need some way of referring to the perceived mental states..and I do believe that brain=behavior, but that it is also valid to speak of our subjective experiences as something separate from the mechanisms that they _are_, because what they are is not what they seem to be. I just think we should keep in mind that this separation is simply useful for our discussion, not a representation of reality. But then you're right; if I speak of "perceived mental states" this way there is no interface - that was a poor choice of words. Perhaps "relationship" would have been more appropriate. I don't think we can deny the existence of a relationship. >I haven't seen the Searle, but I take it that he and Dennett don't quite get along. Do you happen to have a copy?

Hmmm. If brain=behavior, how can there be "an interface between [the brain's] mechanisms and our perceived mental states"? Presumably, perceived mental states are themselves brain mechanisms? So what is the real problem in characterizing consciousness as a brain process? Glad you like Dennet, I did too. But even he doesn't, it seems to me QUITE put his finger on the problem, as pointed out by John Searle in a two part NY Review essay (starting 2 Nov 1995). Have you seen it? Sure, it has something to do with verbal report, but I think there are some additional subtleties. Let's keep the question (and ambition) in mind, and see where we are at the end of the semester. PG

Have the originals, from which copies can be made. Searle has the same problem with Dennet you do, accusing him of trying to make the qualia experience disappear. And I agree with you (I think) that making them disappear is missing the point. If brain=behavior, then something about the brain has to explain what gives rise to the experience of qualia. That's the additional subtlety. Any idea how to deal with this?


Coordination of Independent Parts of the Nervous System to Produce Behavior

Given that the range of behaviors that any given organism performs is so varied, and that variety can even be found in the outputs elicited by the same input, the concept of several different autonomous parts of the nervous system acting together to form behaviors seems logical. While having a large number of boxes in the nervous system may account for some of the wide range of behaviors, I feel there are not enough boxes to account for every behavior in a 1:1 relationship. How would one explain small variations on the same behavior? Would each variation be controlled by its own individual box? If so, I would think that the number of boxes needed would approach infinity. Additionally, what would be the cause of different outputs across trials, given the same input? Would all the outputs stem from the same box, or would there be a separate box for each output? (i.e., is there one box that does all the controlling for smacking mosquitoes; or separate boxes for smacking mosquitoes with the right hand, the left hand, or mosquitoes appearing on the left side of one's body as opposed to the right, etc.) If there were separate boxes for each output to the same input, one could also see that the number of boxes necessary would be staggering. AA cooperative effort between independent elements of the nervous system would provide another way of generating variability (aside from the mere existence of so many boxes). Perhaps Part A of the nervous system is very involved in generating one response while Part B is not, yet in generating a different response, Part B is very active while Part A is less involved. By varying the degree of activity of a given part, it would seem that one could generate several different behaviors. IIn the Stroop test, subjects are asked to identify the color in which a word is flashed (at threshold levels) on a computer screen. Perhaps one portion of the nervous system (Part A) is very active in identifying color, while another portion (Part B) is highly involved in word recognition. In this task, Part A should be more active than Part B. If, however, the stimulus words that are presented are color names themselves, (i.e., the word "yellow" written in yellow), subjects take longer to identify the color of the word if the stimulus word is incongruent with the color in which the word is printed (i.e., writing the word "red" in blue). This could be considered a different behavior: Behavior 1 is a short reaction time, Behavior 2 is a long reaction time. In this instance, it would seem that the word recognition portion (Part B) has increased its input to behavior, and Part A has less input. Perhaps this is one of the ways in which the diversity in our behavior is generated: behavior is the summation of the input of several sometimes cooperating, sometimes competing, independent influences. By varying the degree of input of nervous system elements, one can vary the behavior output.

VERY interesting thoughts about how to get both lots of behaviors and variability in each. Yes, indeed, we shouldn't be equating one behavior with one box. William James is probably the foremost American philosopher and certainly the founder of American psychology. Fascinating man, fascinating family (brother was the novelist Henry James). PG

I'm not familiar with William James--is he a biologist? I'll have to look into it... Maybe you can make sense of the appearance of ghosts by monitoring the neural activity of people while they are seeing the "ghost." I guess that would be hard to do. How do you tell a tempermental ghost when to manifest? Along the same lines, maybe we could monitor the neural activity of mediums..


An interesting topic, at least to me, came out of that discussion of the cricket song on thursday. The females have a more favorable response to their "brothers" songs then their parents songs. This makes sense to me, they still respond to the parental songs just not as favorably therefore it appears to be a ratio of stability genetically speaking versus the evollutionary variation necessity. What I realized however was that a similar thing happens in humans. In my social psychology class we found out that both in sexual and nonsexual relationships humans tended to like people similar to themselves in appearance and likes and dislikes. What seems to make completely rational in crickets doesn't make as much sense with humans. This also indicates that there are markers in the brain which are stimulated upon meeting someone like yourself. If this is true why are some couples exact opposites or some friends completely different yet the relationship is wonderful. Perhaps due to the extreme mixing (at least in America) of different nationalities and races has caused this to become less of a factor int he genetic makeup of individuals. Yet that doesn't describe how humans were able to get around that impulse in the first place. In evolutionary terms it could have been a result of the exponential growth of the human populace where it no longer became necessaryto choose for "perfect" specimens. Any disease or other disaster that comes along will affect such a small percentage of the population because of our pure numbers that we no longer have to always choose for specimens like ourself. Another interesting topic this week was whether or not there is a he/she within the spinal cord. I dont believe so because there is not difference between two people if all they can do is react to inputs. And even without the ability to move your foot a way from a burning candle you still can have other behaviors as dictated by the brain. One thing that greatly intrigues me involves the 10^12 neurons we have in our brain. I can accept that these neuron using different patterns can create all the different behaviors we exibite. What however about inputs we have never gotten before, or for that matter anyone has gotten before? How about something as outragous as discovering you could will yourself through walls? Perhaps the brain contains the necessary neurons but it certainly has never gone through that pattern before. This would however explain the increased amount of time it takes to deal with experiences new to you. Are signals sent around until the correct connections are finally made or is it possible to increase the number of connections between neurons that we have? I'll have to think about this some more.

Very interesting issue: the drive to homogeniety versus heterogeneity as we discussed it in class. Yes, of course, it shows in human behavior. Suspect the answer to how come some people look for likes and others unlikes is more local than global. Some brains, I suspect, prefer novelty and complementarity, others prefer stability and similarity. Part of the variance within human populations? Your spinal cord argument is pretty brief and a little vague. Spinal cords MIGHT differ in how they react to things, would that be enough evidence for a "he/she"? How deal with things never dealt with before is a VERY interesting question. Keep thinking about it, ok? And raise it again if we don't seem to deal adequately with it by the end of the course. PG


"Is there a laughing neuron?"

We have estabilshed in class that a "behavior" can also be thought of as a "pattern of activity involving a large number of elements." We have also learned that there are at least ten to the twelfth neurons in the human nervous system. There must be at least that many different types of behaviors, given the complexity of human behavior. At this point it does not make sense to argue that there is one specific neuron, or type of neuron, that after receiving input produces the output of the behavior called "laughter."

Now, I think the question should be, is there a specific "laugh pattern"? Can the output of laughter be traced always to a firing of certain neurons in a set sequence? Is there a pathway, a "laugh track," of connected neurons somewhere in the nervous system that always produces laughter as a behavior when it is followed?

If there were a track of neurons that were used only for laughter, there would be the possibility for it to be an unalterable path, producing an unalterable pattern. If the first neuron of the track were fired, the rest would follow inevitably, resulting in a laugh. However, the rigidity of this model lends an unbelievable inflexibility to the structure: The laugh behavior would be affected drastically. If one of the neurons in the path were altered, the whole pattern would be thrown off. Perhaps the incompletion of the pathway would result in an inability to laugh.

However, the fact that there is a very large number of neurons in the nervous system suggests that there is, in fact, a complex interconnectivity between them. This must lead to a great flexibilty of patterns. We know that every neuron is connected to about 2000 others. Though there may be a set sequence of specialized neurons activated in a specific pattern which produces a laugh, each neuron in that path is communicating with many other pathways. So at any point in the pathway, the pattern could be changed by information coming from other inputs to any one particular neuron. Here, the behavior of laughter would not be incapacitated by an alteration, rather it would be "influenced". For example, whereas the behavior occuring after a joke is not necessarily inevitable, for some people, tickling produces uncontrollable laughter. This leads me to believe that not only is there not a specific "laughing neuron," there does not seem to be a specific set of neurons working in a pattern. Unfortunately this brief analysis must end with almost as much ambiguity with which it started: it seems that there may not even be a specific pattern of neuron firing that always results in laughter.

Very nice, very sophisticated set of thoughts/questions. Roughly brings one quickly to the current state of neurobiology. Yes, no laugh neuron. Yes, not even a fixed laugh neuron path. Lots of neurons, with capability to be "influenced" without abolishing laugh, which of course means lots of different "laughs" with small variations among them. Now, how come we have a word for "laugh"? What's different between "laugh" and "cry"? How come there appear to be discrete kinds of behavior? Good problems, want to become a graduate student in neurobiology, work on them for the rest of your life? PG


The question of whether 10^12 "little boxes" enhances or diminishes the functionings of the nervous system and consequently behavior possess many facets.

A valid question asked quite often in modern society is whether our brains are improving. If so, in what direction(s) are our evolving brains taking us? Hypotheses abound stating that rather than enlarging or using more of the brain, the trick is to make the brain work more efficiently. If so, would that mean instead of growing newer, more specialized regions for input processing, our brains are in the process of growing more neurons? Considering the fact that mature neurons are the only types of cells incapable of regenerating new, this poses a problem towards the spontaneous formation of additional neurons. Even assuming that newer, more specialized regions were too come into play, simple physiology tells us that some region of control would have to changed or be drastically modified in order to make room in the limited surface area imposed by the skull. Even with this amazing number of neurons, problems of communication and coordination do crop up. However, with the limitless possibilities afforded by many neurons, it becomes difficult to determine what is actually neurological from what is environmental, immitated, etc. It appears though, that the more neurons an organism posesses, the greater the chance of disorders becomes. For example, schizophrenia brought upon by excess amounts of dopamine in the brain occurs due to malfunctions in the regulatory system of the brain. These sorts of disorder don't regularly appear in lower organinsm presumably. Nevertheless, the presence of these regulatory systems indicate a beneficial co-evolution of control for the neural functionings. With the infinite possibilities of the neurons, an interesting concept is whether the brain has the ability to heal itself. Experiments with chimpanzees indicate that areas of the body which were in effect paralyzed by making lesions in the brain, were able to form primative circuitous pathways. This open up immense possibilites for victims of paralysis, head injuries, stroke, etc.

Overall, it appears that with the extraordinary amount of neurons in the human brain, the increased array of behaviors and functions far out weigh the negatives of neurological disorders. Current experiments indicate even more possibilities hitherto unkown in the area of brain repair and bodily healing.

Interesting questions. What is "improving" or "efficiently"? How would one measure them? Particularly like the notion that increasing neuron number might bring benefits (why exactly?) as well as problems. What do you mean by "primitive circuitous pathways"? Where have you been reading about it? PG


1,000,000,000,000+ neurons is an amazing number of them! It is hard to imagine such an outstanding number. I have had professors in the past who try to help us envision what different orders of magnitude mean, especially when they are very large or very small. Dr. Francl was talking about atoms once, and she said that X amount (whatever astronomical amount was being discussed that day) would create a mile-deep layer over the whole continental United States if they were M&M's. Obviously, the vision of that much chocolate had an impression on me, but the idea that I have about 10^12 neuons INSIDE OF ME... WOW!

I have been told, however, that no new neurons are ever created ant that neurons cannot self-repair when cut. I've also been informed that they die at a rather alarming rate. I know that there is a lot of replication within the nervous system, but I cannot understand why Whomever created and organized all these boxes-within-boxes would not give it the power to fix broken boxes or create new ones. I'm also at a loss for how paraplegics "learn to walk again." When the neurons in the spinal cord are severed and cannot be fixed, what relays the messages from the brain to the motor neurons if no new neurons are formed? So many questions...

Nice questions, can imagine testable answers? How look for them? No neurons created and no regeneration are both old summaries of observations which are currently being looked at anew. And supposed NO ONE created the whole thing. Would it now make more sense that its repair capabilities are limited? Can you think of any other reason why this might be so? PG


Last week, when I was reading some articles in the Scientific American, I moved into the micro world of cells. I was fascinated by the photographs of neurons, and their organization. Before that it was not clear to me how can one know so much in such a detailed way about neurons, the communication of information between them and especially their number. In fact, it still is not quite clear to me how can one count (or even approximate) 10^10 neurons. When I move to such a microscopic world with such an immense number of little particles, it seems unbelievable that this would be all that would compose something as complex as human behavior. In some ways it is even more unbelievable now than a week ago, when I just knew about a schematic and still very abstract OboxO, which at that point still had the potential of containing something mysterious, that would be capable of generating behavior. In particular, itOs hard for me to believe that one particular behavior would be mere (although complex) composition of neurons and movement of chemicals between them: I am talking about the sense of self. I am very curious about our future discussion of the OI functionO that you mentioned today since, I will not very easily accept the proposition that humans are just systems of chemicals.

There were many times in my life when I stopped in front of a mirror and thought: Owait a second, this is me!.O And to convince myself that the physical object that I can see in the mirror and parts of which I can see even without a mirror, is really me, I used to punch my hand. I thought: I can feel, so it must be me. Although I am still amazed by the fact that I am alive, I already know that mere feeling does not prove that the body is really me. I learned that paraplegics do not feel pain but they still have their sense of self. We concluded that since the brain canOt feel the pain (or move legs) implies he/she canOt feel the pain, he/she must therefore be located in the brain. In order to disprove this proposition, we would have to find an activity which spinal cord canOt do and therefore we canOt do. BBut I am not as much interested in where OI O is located, as in its nature. Is it just a illusion that we recognize ourselves? Can we be sure the I am really I? Suppose we take our identity, what we consider our selves. Now we follow Descartes and subtract whatever we have been given on arbitrary basis in this world and accepted as ours: identity that is created by our bodies, our names, education (and any experience in the past). Now, after the knowledge of paraplegics we subtract even our feelings? What is left when we subtract all that? Is there anything at all? I guess I finally brought myself to the question that I would like to get some enlightenment on in this course. I would like to learn about all other things do we have to subtract to get to the pure self. Alternatively, I am hoping to challenge this way of thinking about self as a composition of many acquired things and (possibly) some real permanent OIO.

No problem. Thanks for very thoughtful, interesting essay. VERY intriguing way to pose the question about the nature of the self ( the "I function"). We will indeed talk over and over about how many things can be done without a sense of self (the equivalent of trying to find self by subtracting?). Suspect that where we'll come out is that you can't FIND self that way, that you can subtract any one of a number of things without losing self, but that if you subtract ALL of them, self disappears. Off the top of my head thoughts since I'd never thought of the question the way you posed it. Let's see what happens as the course goes on. PG


We have established through past lectures that the nervous system is essentially comprised of about 10^12 little boxes or individual segments within our nervous system. How could this influence the way in which we link the nervous system to behavior? We as individuals distinguish each other based on many different characteristics one of which is behavior. We have heard the phrase many times: "no two people are alike". This could be easily explained if we were to accept the notion that the nervous system and behavior are one in the same. Because of the vast number of base units in our nervous system, the amount of different possibilities for behavior are overwhelming, thereby increasing the likelihood that no two people will behave the same way. This also maintains our theories of individual differences.

If we accept that the nervous system and behavior are the same then we can see that behavior is regulated by both the spinal chord and the brain. The distinction I see is that they function on two different aspects of behavior. It seems as though the spinal chord has the function of carrying out the task whereas the brain is responsible for the individuation of the behavior (ie making the behavior distinct and characteristic of that organism). Through this approach, we may be able to see a correlation between the size of the brain and the amount of individual variation in behavior from species to species. IIf this theory is correct what does it say about the he/she question(where is it located?). When we think of the term he or she it is specifically referring to one individual. That individual is distinguished by characteritic physical or behavioral traits and since I feel that those are controlled by the brain I feel that the he/she is located in the brain as well. Hence we say about a quadrapalegic that he/she can't move their leg (meaning they can't influence what the spinal chord does because the connection is cut. The spinal chord still can create movement but it can't influence behavior.

Like the approach to self through individuality, argument for a high degree of individuality given numbers of neurons. Distinction between creating movement and influencing behavior which you try and make at the end is less clear to me. Suspect the spinal cord is every bit as much individuated from individual to individual as the brain? PG


We have recently agreed in lecture that our brain is a box which can be subdivided into smaller boxes and this subdivision continues until we are presented with the smallest box possible - the neuron. Each of these boxes has their own inputs and outputs either of which may be generated and terminated within the brain itself (need not be connected to the outside world).

A rough estimation of the total number of neurons in the body is around 10 to the power twelve. This is an amazingly large number. Also determined is that the total population of neurons that have either their receiving or transmitting surfaces outside the nervous system is so tiny that it suggests that the majority of our behaviour is a result of the intercommunication between the different parts of the nervous system and has very little to do with the outside world. The example of the paraplegic also demonstrates how vital contiguity within the nervous system really is. The above example also clearly shows that although responses (certain behaviours/outputs) are possible without impulses travelling to the brain, the brain is essential if that particular behaviour is to be executed with the efficiency and precision required.

This concept makes sense. I find myself making an analogy with say, the auto industry. For the perfect car to role off the lines, you need each section of the company which manufactures different components of the car to function properly themselves and to then have the administration which, like the brain, connects all these sections of the company to ensure that everybody remains in contact with each other and so enabling the production of the car. Behaviour very seldomly involves only a physical action. Often this is all that is visible but there are also many other components to each behaviour that we exhibit such as thoughts, emotion and so forth. Each behaviour can only be executed after taking into account information from a bunch of other places and thus, if these regions were not connected then we would be wrecks! (if we were at all!)

The entire concept of contiguity makes a lot of sense but I find myself asking what is there to tell the brain what to do? The impression I have so far is that one box feeds inputs into another box and this continues for some time until a particular box no longer sends out an output. What I find myself asking is that where does that intial input into that initial box come from? If it is an order from the brain, what makes the brain give out that order? Are there impulses involved in that too? How does the brain function the way that it does?

Fair questions, some answers hopefully in a few weeks (after we talk for a while about the littlest boxes). Worth thinking about yourself though while we're working up to it. Along which lines, your analogy to a factory, in which different parts do different things, is appropriate. But, are you sure there is necessarily a big boss in the factory from whom all action initiates? Possible that different parts initiate their own actions? And are you sure the big boss (the brain) is necessary for "maximum efficiency and precision"? Maybe often things work better if they are more or less left alone? PG


To decide whether there is a he/she present in the caudal end of the central nervous system as well as in the rostral end one needs a good definition of he/she and a lot of evidence. What constitutes He/she? It is probably not only an ability to feel, but also a power to think and a conscience. Is he/she something that is present eveywhere in a body - and is there therefore no separation of brain, consciousness and the organism ? Is he/she the self-consciousness of an organism, something that tells it that it is present and alive. And where is this he / she located? IIt happens, that when a person with a lower parts of the body disconnected from the rest, a paraplegic, is pinched and his leg moves away without him knowng what happened to it we can not say that his leg has a separate he/she inside. Paraplegic's brain can no longer control his legs because there is no continuity between them. So moving a leg away is only a reflex, and the feeling of pain due to which the leg moved is not proof enough that the leg is separately conscious of anything else. When a sleeping person is pinched, he moves away because there is some pattern of activity which tells him to move away from the pain. The rest of his body and his consciousness don't appear to have been involved in anything. An input in the spinal cord doesn't have to go to brain, it can be interpreted in the spinal cord, and produce output. It seems that reacting to pain by moving the body part affected away is something which happens subconsciously without any involving on the part of a he/she. HHe/she is more than controlling the withdrawing of a pinched toe or leg. It is also feelings, emotions, an ability for abstract thinking and many other facilities which we know are centered in the brain. Cutting a limb away does not diminish person's ability for thought, and so there can be no he/she in any particular part of the body, but in the brain; and some conscience of the rest of the body also present in the central nervous system. We don't know whether the pinched toe of a paraplegic feels any pain because there is no he/she, no conscience which would tell us what he feels there.

I think what you're saying is that there doesn't NEED to be consciousness for the spinal cord to cause foot withdrawal to a painful stimulus. But what you don't tell me is what additional observations we ought to try and make to determine whether there IS consciousness there. Are you certain there isn't? As opposed to there needn't be? If so, why?

The notion of 10*10^12 interconnected boxes in the brain coupled with the thought that nervous system and behavior can be explained in each other's terms, is a little unsettling, because even though I know very little about either of them, I can't even imagine how complicated behavior is if it is determined by all the connections of the neurons.

Why? What else do you need to know? Hopefully, we'll get there. PG


Although I am still unable to completely accept the argument that the nervous system (including the brain) and behavior are the same, it seems as though the more I learn about the construction of the nervous system, the more I am inclined to think, "It (the argument) may really be true." The neuron is the basic unit of the brain and the nervous system. In fact, there are about 10^12+ neurons in humans. This enormous number of "small boxes" that are contained within relatively larger ones which are also contained within larger ones (and so on) quanitatively supports the argument that the nervous system is behavior. This new information can account for the many different behaviors exhibited by people. More specifically, we have an enormous (yet finite) amount of neurons which seems to correlate with our finite number of behaviors that are also too many to count. However, even more influencing evidence is the manner in which the neurons are connected to other neurons. They are interconnected in such a way that each neuron in the human brain has hundreds to thousands of connections to other neurons. In other words, a single neuron is receiving about a thousand signals from different neurons and it is sending about a thousand signals to other neurons (whether to the same input ones or to different ones). Therefore, these complex and important interconnections allow numerous neurons to communicate and to cooperate efficiently and effectively by creating many pathways, accounting for an even greater variety of behavior. So by learning about the complex components and structures of the nervous system, I realize that the brain is much more complicated than I had imagined and it can be possible that it is behavior. IIn addition to the things we have learned in class, I have also been somewhat influenced that the brain and behavior are the same from some reading that I have done. In a recent article from 'Science' magazine, researchers suspect that in crayfish a change in behavior also changes their nervous systems (and under the assumption that the brain and behavior are the same, this would make absolute sense). In short, scientists have been performing experiments with this animal and they have found that according to the animal's social status (dominant or submissive), a neuron reponds differently to serotonin, a neurotransmitter. For example, in the dominant crayfish "the neuron is more likely to fire" due to serotonin while the opposite occurs in the subordinate crayfish. Therefore, with such current findings also supporting the argument, it is becoming more difficult to dispute.

More interesting issues, and glad you're finding some additional things to read. Numbers of boxes, and their interconnectivity certainly help in the argument. Are you sure though that behavior is "finite"? I haven't read the Science paper yet, but it was mentioned to me last week by Peter Brodfuehrer and sounds intriguing as part of an emerging effort to make neurobiological sense of social interactions. PG


Although parts of the nervous system are independent and capable of doing different things as with the example of a parapalegic still being able to jerk away when his toe was pinched, behavior still, in my mind, remains a phenomenon of communication between different "boxes" in the nervous system as defined in class this week.

Communication in the nervous system is, needless to say, still an integral part of behavior. Even though a parapalegic is able to pull his foot away, the complete output of behavior is not displayed. The parapalegic is supposed to say "ouch" or exhibit some physical display of discomfort. However, he, the person, does not feel any pain and therefore the parapalegic's behavior is abnormal because there is a breach of communication in the nervous system. So even in this instance, one can observe the importance of communication in the nervous system and how the breakdown of communication affects behavior.

The above definition of behavior can also be used to define the world: the world is a phenemenon of communication between boxes. If you look around, you can clearly see that this definition applies. The boxes are people and all other living things. Each of the boxes are capable of doing certain things in and of itself which we ought to do but the world would not be a world if we did not communicate or interact somehow. You couldn't study one person and expect to understand the world. The same applies for behavior.

Interesting extension from the brain to the world (reality?) at large. Would like to hear more specifics about how you mean this. Yes, indeed, many behavioral abnormalities probably correspond to interruption of coordination. PG


Ever since Descartes work on the mind body duality, our society has espoused the notion that the mind and body are two seperate entities. As a result, when someone has a stomach ache they consult an internist, however if he is depressed and has stomach pains he consults a psychiatrist. This society has also been led to believe that the essence of a human--his being--is contained in the mind. The body is merely a robotic apparatus which can be replaced by spare part surgery, or augmented by plastic surgery. In this culture we believe that I would still be me if I lost my legs to perhaps a mine, or if an arm was amputated, or if I lost a finger, or had my ears pinned back. In other cultures, such cartesian distinctions between the mind and the body are not made, they are seen as inseperable and both constitute a person's self and essence.

This leads to an interesting predicament. We were talking in class about the hypothetical case of a paralysis victim and we were wondering if "he"(his self) was contained solely in his brain and not even his spinal cord. Although he had no control over parts of his body, except those regions above his neck, he could still think and had full cognitive function. He was still a rational and thinking individual even though some of his physical apparatus was lost. For some reason, I am hesitant to accept the fact that his essence or self is concentrated inside the anatomical region known as the brain. Instead, I believe that one's physical apparatus is closely linked to an individuals identity and self and is so central to it that once it is removed or seperated it is a new self which has emerged, which incorporates both the thinking and workings of the brain with the new physical capabilities(and disabilities) of the body. It is not fair nor accurate to say that a certain self existed in the brain of the paralyzed victim all along, and the body was solely a casing for the self which could assume any form and the self is still in the brain,. When we describe the self in our society it must incorporate both the mind and the body. Obviously, the self of Christopher Reeves in the superman movies is a different self than exist in him after his horse accident. Actually, this whole argument is probably not very rational for I never was good at philosophy.

On the subject of the immense number of neurons in the brain and how this relates to control of behavior, it seems obvious that this finding opens up numerous possibilities. The implications for behavior, for a neuron which is bordered by a couple of thousand other neurons seem evident. However, in a way it also confounds the subject, with a number as massive as ten to the twelve, it seems unlikely that we will ever develop a satisfactory explanation, instead we can merely say, that the nervous system is so large and so complex that it is rally beyond our comprehension.

Philosophy is fine. So is cultural relativism, and a sense of identity which includes not only brain but also spinal cord and body and maybe a host of other things as well. But its ALSO true that a paraplegic (in any culture, I presume, though this might be worth looking at) when asked to move his/her leg says *I* can't, implying that in SOME sense self is not only not coextensive with the body but not even coexistence with the entire nervous system (since the spinal cord CAN move the leg). There are other less dramatic but no less interesting examples of this (many of which would also be looking at the cultural dependence of): objects are usually perceived to be pointing at you if they point toward your eyes but not if they point toward your toe; when a arm or leg is "asleep" one sometimes is uncertain whether it belongs to oneself or not. In any case, I can (and do) accept your point (the self is different if it is located in a different body) without having to give up mine (the sense of self is frequently localizable).

As for satisfactory explanations, they certainly are not going to involve accounting individually for the behavior of so vast a number of neurons. But there may not be a necessity for that, if we can find an appropriate and useful way to talk about groups of them. We'll try. Let me know if it works. PG


It is likely that having 10 to the 12 boxes inside other boxes enhances the nervous system rather than limits it. The fact that there are such a numerous amount of neurons must signify that there is an adequete number to facilliate all the actions that the nervous system must perform. I do not feel that it would be too much or it might have eventually disappeared due to evolution; instead, as the animal becomes more complicated the number of neurons most likely increased as did the brain structures, etc.

Considering how much work the nervous system does in its entirity, the idea that I cannot really conceptualize the amount of neurons that seem to exist furthers the idea that so much occurs within the nervous system, especially since I even cannot completely conceptualize everything that the nervous system itself does. I walk which I understand but why do I dream or hope and do rabbits or sponges hope? The brain is so complicated that scientists have no clue as to which piece does exactly what or why certain beings have certain preferences or on and on. However, the high number of neurons suggests that each part has its own set job that it is required to peform, such as a motor neuron in the finger is responsible to get this finger to type. >Some might feel that the large number might hinder operation as everything occurs in patterns for a response. Due to the large number, I do not see how the neurons would slow down response time; instead, I see the entire system as an assymbly line, each area with its own focus. Such a notion definitely combines well to the observation that behavior is the communication of "stuff" to create the certain behavior/action/inaction/etc. Because of some many neurons, the certain pathway is activated as it slowly moves towards the appropriate place for the output to occur.

You make it sound awfully easy. Problem is, if there are JUST little input output boxes doing very simple things (as we'll see), can that REALLY be feeling/thinking etc? Interesting question though: does the extraordinary number of boxes in any way make it harder for the nervous system? Hadn't thought about that one, is worth thinking more about. Thanks. PG


I think we came to the conclusion that the fact that the spinal cord can cause movement independent of help from the brain does not really mean that there is a he or a to be found the cord. I think we decided this based on the fact that the most that will happen is a pulling- away motion in response to a pinch or so or a pretty bad attempt at walking, due to fact that balance lies inthe brain. I guess that, in science fiction movies about genetic engineering and robotics, loving scientists come to call their creations, however marginally human, by name, and refer to them as he or she, but we will ignore them - they're obsessed.

What would we well-adjusted people need to see in order to call something he or she? Fundamental is an awareness of self - the he or she should know that he or she is a he or she, so to speak. How would she demonstrate this? One sure way is to refer to herself in speech. In order to do this, one needs the brain. But she might be deaf or mute. The spinal cord would probably have a tough time learning sign language. So if she could understand someone's inquiries, she could point to herself. In order to understand, she would need either audition or vision as wellas the knowledge of a symbolic language.

In order to demonstrate the myriad 'reactions' or behaviors hes and shes are capable of, the he needs a few senses other than those possessed byt he spinal cord For instance, in the event that we pinch the foot of the he and he pulls away, we would interpret the action as one typical of hes, even if we might expect a concurrent ouch of some sort. After a while, it would become apparent that a he without access to a brain was only very marginally a he when we notice that he is limited to movements below the neck. I have no idea what we are to suppose about his facial expression, but the fact that it isn't changing will prob- ably get interpreted as the final clue to a lack of he. A very large part of he is on the face. Until the spinal cord gains the ability to control movement above the neck, there will be no chance of a she-he. There will be little more than a chance until the spinal cord takes control of speech, hearing and vision (and arguably smell, which is only a tip off if the she doesn't run from skunks.

Think we came to a slightly different conclusion: that we couldn't tell whether the spinal cord has a he or she (a "self"?). You've clearly got the problem right: is hard to tell if there is a "self" there without speech or facial expressions or SOMETHING to appear self-referential. But one could make a computer with a sound capability, and give it the capacity to say "I see you". Would THAT be adequate evidence? Possible that the existence of a sense of self is neither disprovable NOR provable? Let's keep working on it, huh? PG


Does the 1012 little boxes within one big box enhance or diminish the assertion- the nervous system is behavior?

I understand that the brain can be thought of as one large box consisting of series of smaller boxes. The smallest box, the neuron, contains both inputs and outputs. Of the total possible 1012 neurons in the brain, only .0002 percent are sensory neurons and motor neurons. If the remaining 99.9998 percent are interneurons, this suggests that most of behavior is communication between neurons within the nervous system. This is where I have a problem because it diminishes the role of the environment in behavior.

Each neuron receives 1000 messages from other neurons and sends 1000 messages. Does each individual message received have an equal impact on behavior? Although the sensory neurons are fewer in number, is their input of greater significance than input from interneurons?

If behavior is mostly influenced by internuerons within the nervous system which are not in contact with outside stimuli and each brain is unique, why are there strong similarities in behavior among certain groups of individuals? For example, there are statistics which demonstrate that Asian Americans tend to score higher on SATs then other racial/ethnic groups. I am not sure how this could be explained in solely terms of internuerons. Does the environment somehow impact the interneurons without necessarily going through the sensory neurons? Where does the environment or culture enter in as influencing factors on behavior? It seems that so much of our behavior is the result of outside stimuli rather than inside the workings of the nervous system. If the sensory neurons, which I assume is the only contact the brain(nervous system)has with the outside environment, had a greater impact on behavior even with its smaller numbers, it would be more easy for me to believe that the nervous system is behavior.

Interesting, highly appropriate wonderings. Doubt the environment can influence interneurons without going through sensory neurons. Info from sensory neurons can certainly influence interneurons and does. But possible that your sense of the environment as THE principal determinant of behavior is over strong? Maybe interneurons reflect influences in addition to the environment? Worth mulling over, and something we'll come back to several times in the course. PG


I would argue that there is NOT a he/she in the spinal cord. As was said in class, a paraplegic withdrawing a pinched toe, or, an input leading successfully to an output without reaching the brain first, is NOT enough evidence to say that there's a he/she in the spinal cord. The spinal cord may be able to accomplish this movement without the help of the brain, but there aren't too many other actions that the spinal cord can do on it's own. The reason that the paraplegic is capable of moving but can't do it anyway is simply that the connection from the spinal cord to the he/she that controls everything is interrupted. When considering what characteristics are necessary for having a he/she in the spinal cord (or what observations would prove to us that this existed), all of these class thoughts and comments could be brought into our formulation of criterium. I would say, first off, that a basic characteristic would be the necessity of function. For example, when part of our spinal cord is not able to function or stops functioning for some reason (perhaps a lack of continuum with the brain), the disability that results is not considered to be quite as serious as if the brain were to stop functioning. When we argue that the brain IS the he/she, the first thing that comes to mind is that a functionless brain is usually called being brain- dead, and people that become or are brain-dead usually do not go on existing very much longer. When someone is brain-dead, they usually turn off life support, and that probably doesn't happen quite as often with people that are paralyzed or with people that have interruptions in the functioning of the spinal cord. This is probably a really basic and ridiculous idea, and probably lots of it is wrong, but that's the first thing I thought of when I decided that there was no he/she in the spinal cord. So that's one criterium.

Another would be the idea of responsibility. The brain, it seems, is responsible for overseeing everything that goes on in the body. The brain makes our decisions, and if we have problems that affect our personality, we give it drugs to help it make us better. This is another really simplistic view, but if a person is depressed, we don't give them drugs that will act on their spinal cord. This argument can probably be shot down by saying,'well, if you have a heart problem, you give someone heart medication, not medication for a mental disorder', but it seems that to be a he/she in the human body, you have to be responsible for most of the things that the body carries out. The heart may be responsible for getting blood to the brain so it can function, but if we say that the brain=behavior, then it seems that the brain is responsible for a fair amount of bodily functions. If the spinal cord=behavior, then we might say that it's importance in the body is of great significance, and we ought to consider if our personality is the spinal cord. So I guess that's kind of getting back to some of the things we discussed last week. Is behavior everything we are? If so, and we go on the assumption that the brain=behavior, then you've sort of answered your own question. Maybe that's what you were trying to show us, and then agian, maybe I'm just missing the boat. See you in class

Interesting ideas (but be careful about vocabulary, the word is "criterion", and try and find time to write over the weekend, ok?). "Function" is a little vague, and there are actually a lot more things the spinal cord can do by itself than we have yet talked about. Its true that the medical profession currently uses "brain-dead" has significant, but could that be because they have never thought of the question of whether there is a "he/she" in the spinal cord? "Responsibility" is also an interesting approach to the problem, though perhaps in a way different from the way you were using the word. We'll find that the "brain" isn't really a master controller for everything else, but only part of a system of cooperating controllers of which the spinal cord is also one. On the other hand, one might try and make a useful argument about responsibility in the "being held responsible" sense. We tend to hold "he/she"'s more responsible for some kinds of behavior than others, and THAT (if we had a way to specify why we do that) might provide a way to decide whether there is a he/she in the spinal cord. PG


Taken as a given that our sense of self resides within our nervous system, we are led further to the question of exactly where and how within that system it resides. This is far too complex a question to address in anything less than a full length Scientific American article, but perhaps we can narrow it down a bit. As to the question of _where_ our sense of self can be found, the "knee jerk" response might be "in the brain, of course."

Certainly it is reasonable to assume that much of what our conscious selves are composed lies in our brain. With ten to the eleventh of our ten to the tenth neurons existing in the cerebral cortex alone, it is clear that pure neurological computing power is weighted in favor of the structure in our heads. Yet possibly it would be a mistake to limit our sense of self to cranial gray matter. The neuronal network found below the neck may seem to pale in comparison with the wonderful complexity of the brain, yet it would seem to rival the complexity of the brains of many lower lifeforms on earth. Would it not be hasty to rule out its contribution to our own self awareness?

I would not assert that anything in our nervous system south of the head could be independently responsible for writing a novel or solving a complex mathematical problem. Yet many of us would not deny that we ever feel a sense of consciousness below the neck. Surely the satisfaction of a good meal in the belly or the "chills" up one's spine are more than simple processing by the brain of sensory input from the peripheral nervous system. Could they not also be echoes from part of our nervous system working independently of the brain?

When we see a freshly decapitated chicken walk, run, and flap wings in the absence of its head, there lies evidence for some relatively complex neuronal motor interaction taking place in absence of the brain. The neuronal network which makes this possible could contribute to a sense of self even if in a limited capacity. Those of us that have lost a limb can describe the unusual measures the brain will take in trying to communicate with that lost part of its network to include phantom pain and sensation. We know a paraplegic's foot will withdraw when pinched, demonstrating a connection existing below the divide with the brain. Learning about further neurological capabilities from the caudal end of a paraplegic may prove difficult because it obviously cannot talk, but it deserves investigation.

Have you ever thought exactly what it means for someone to say "my head tells me one thing, but my gut is telling me. . .?"

Thank you. Nice, interesting collection of reasons to think there MIGHT be consciousness in the spinal cord. Now, the tough question. What new observations ought one to make to try and settle the matter (or at least shed further light on it)? PG


in reference to the idea that the same set of elements can act in a variety of different patterns leads me to the assumption that there is an infinite number of possible pathways by which neurons can choose to communicate. what i am most curious to understand is how each neuron decides who their next victim of synapsing will be. numerous interactions occur so quickly that there must be an immediate reason for each neuron's preference in dendrite. they do have a choice, don't they? i realize that my knowledge is limited, so i'm prepared to be wrong by using an example of a neuron who has been told by his last informer that his job is to make it possible for his master (the body) to slap someone on the back. let's naively say that he's got twenty choices of neurons on which he can let the secret loose. he knows that he'll need the help of a few, but which few is the question. it's not like each surrounding neuron is holding his/her own road sign, "This way to the Florida Keys - ", so how does he know that his choice will ultimately result in a slap in the back and not a slap in the face? same elements... different pattern...

Nice question, interesting thoughts. Probably first worth asking whether "choosing" or "choice" is a relevant concept for something as "simple" (?) as a neuron. Assuming so, the question is largely one of development, and we'll talk a bit about it in these terms at the end of the course (though you could jump ahead with some of the assigned Sci Am articles). Until recently, the presumption has been that such choices are made fairly early in life and then remain stable. That feeling is beginning to change though to some extent, and your questions have new relevance: if neurons are changing connections, how would they know what ones to make? Any ideas? PG


The nervous system is made up of interconnected boxes or neurons. Behavior is believed to be the result of lots of these neurons sending messageThere is not a single neuron for each behavior, but instead, behavior results from the pattern of activity of the neurons. If the nervous system is composed of 10^12 neurons, it would seem that this large number of neurons could combinein different patterns to produce a variety of behavior. The large number of neurons makes me believe that it is possible that the nervous system and behavior are the same thing. One can consider running and walking, two different behaviors that use the same muscles. If the same muscles are used then the output from the neurons must be the same. Different patterns of activity of neurons can produce the same output. Something makes the legs move faster in running and not in walking. This could be the pattern of neurons involved in the output. The outputs for running and walking might end in the same neurons in the same muscles, but that does not mean that the pattern of neurons signaled during the entire process from input to output is the same in running and walking. Just because the arrow coming out of the box is the same for running and walking, doesn't mean that little boxes inside the big box are having the same response for the two behaviors. Although the nervous system and behavior may not be the same thing, the large number of neurons makes it more likely because a greater variety of patterns and therefore output behaviors could be produced.

Fair enough. But you (and I) need to be clearer about what we mean by "patterns", as opposed to output channels. If this isn't clear to you in the next week or so, check with me. PG


The notion of 1x1012 little boxes enhances my perception of the nervous system and behavior as being the same thing. Since it is not the case that one element (one box) is turned on for a particular behavior while the other elements are turned off, but more likely, it is how large numbers of elements are on and their pattern of activities. When I think about how many keys a piano has, and how many different patterns of music pieces have been composed on it, then the above notion seems highly possible.

Nice perspective (but watch your sentences; that middle one is a doozy). Parallel to possible piano compositions very nice. How many possible piano pieces are there? PG

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