Topic 9: What would you like to investigate further?


So far, we've covered the workings of the input and output sides of the nervous system, with some brief glances into the influence of the "I-function" on both of these. We haven't looked closely at the more elusive qualities of this part of the nervous system yet, such as the question of where it comes from (that is, what might its neural basis be) and what controls it. If it is considered to be the part of the nervous system responsible for the conscious control of behavior, then what influences the function itself? How does consciousness enter into all of this? Why do we experience what we experience?

There are perhaps multiple levels at which subjective experience could be examined. Certain experiences such as qualia like "redness" or "greenness" seem as though they might be easier to explain in terms of physical substrate than others, although even these are (in my opinion) out of reach for the time being. I'm not quite sure if I think it's possible to explain them; what if they are simply the way it is, unsatisfying as this must be? That point of view would make me a mysterian though, which isn't really what I consider myself. So maybe it's just difficult to conceive of a complete explanation at this point. Other kinds of experiences, though, are not merely sensory impressions but cognitive impressions, and others still are combinations of the two, I would say. Thoughts might be an example of the first. The second is harder to pin down...what about the neural basis of humor? That is a question that could be easily banished to the confines of psychology; however, if psychology and biology are truly nonseparable disciplines as far as the mind/brain is concerned this would be a mistake. What is it that makes something funny? Is it a combination of cognitive qualities that produce an emotional reaction? It seems more complicated to define than something like anger or sadness. I don't know why this example in particular is bothering me, but I just realized I'm completely unable to define it.

Agree the I-function knows more treatment, will get to it (of course). Though probably not enough to fully satisfy you (appropriately). Interesting point of yours, to think about more. Yes, I don't think qualia per se are going to turn out to be so difficult (I really do think Damasio helps). Humor is more challenging indeed. PG


As the major premise of this course has been that the "brain IS behavior," in thinking about what topics need to be covered before the semester comes to a close, I'm forced to return to those phenomenon which seem to be unexplainable by the previous assertion. In my case, the best things I came up with were the seeming existence of ghosts (seen by more than one person at a time), and the ability of some mediums to give information which they could not have possibly known without receiving it from the dead.

If those phenomenon can be explained, I will be much more inclined to accept the brain=behavior assertion.

SERIOUS challenge. Fair enough. Can agree that what needs to be accounted for is the human experience of things which seem inexplicable in terms of what we currently know? That the "supernatural" is defined by exclusion, i.e. consists of experiences which we can't account for? If so, then I think we can indeed handle them in terms of brain function. We'll see. PG


We have come a long way to explain the activity of the brain. Behavior which seemed too complex on the first day to be explained is now much more determinable using action potentials, corrolary discharge and cpg's. However this classs has also taught me that is the brain has one mechanism for achieving a desired affect then it has at least six other systems. There is not enough currently known about the brain to answer all of these questions, each minute mechanism gives us more of the picture on how the brain works. We also delved into the optical sensory system full steam, and although the concepts learned here are definitely applicable in other sensory systems it would be nice to get a further understanding of touch, hearing, taste, etc. Another topic which was touched on but not heavily discussed was learning. I do feel competent enough to use the information I have learned to explain how learning occurs but I think further information is needed to answer questions such as is the ability to learn at a specific level genetic. Why are some people really good in one area and not in others? And so on. Another topic we touched on but didn't get completely into is I function and the neocortex. It may be due to a lack of knowledge in that area at this time but at this point I have little understanding of how these make a difference between the higher animals and the lower animals. We know what we can do to end this phenomena but not what we can do to cause it. Overall I feel this course has given me a good general insight into the workings of the brain which will allow me to gain further knowledge as time goes on and let that help me complete the mystery of the brain. Michelle K. Bostick

I'm pleased you have the feeling you have things you can yourself use to make sense of other things. And sorry we don't have time to do some other senses, since they're fun, and there's more there. But let's do do more about learning and genetics, and about the I function and the neocortex, since there are some more generalizable ideas there. PG


Well, I thought I had it all figured out, the idea that the picture in my head is "more real" than the image on my retina. But I was talking with Rufus the other day, and I realized that what I had understood and worked out for myself conceptually could be interpreted differently from what was taught in class. I definitely have some questions.

On the retina, the photoreceptors transduce information about the intensity of light falling on them, they record absolute values of light intensity. Then, the retinal ganglion seem to take the derivative, mathematically, of this information, and only pass along the change of values reported, not absolute values, to the brain. The brain then must fill in between the edges itself. We learned in class that because light intensity is always changing, if we only got the absolute values of light intensity coming from the world around us from instant to instant, we would not be able to have a sense of constancy about anything we saw. In this way, the picture on our retina, light intensity wise, is always changing, making that "reality" less real than we know it. I can recognize a wall despite the fact that depending on the instant, my distance from it, and many other factors, the information on my retina about light intensity coming from the wall is constantly changing. So the conclusion is that because the ganglia use just the derivative of the changing light intensity and pass along only information about relative contrasts, which stay constant, than this is where I get the "reality," consistency, of the wall, and this is more real than what is originally on my retina.

I imagine that if I perceived the light intensity changes, I would perceive the world as if lit by a strobe light. I would see a barrage of situations, each different, from moment to moment. However, I don't. I have to think though that if my ganglia are acknowledging that there are light intensity changes, then they also must know that there are absolute values. To note a change, the ganglia must also note some constancy.

So here is where I am getting confused. First, why is using the derivative of photoreceptor information so different from using the original values? Second, if we say that the photoreceptor information about light intensity is constantly changing, then where is the consistency that the ganglia pick up on and transmit to the brain?

I'm not sure I see the confusion. You've described the "reality" better than I did. The derivitive is more constant under changing lighting conditions. And the constancy that the ganglion cells pick up and transmit to the brain is the derivitive, created by the lateral inhibition network intervening between the photoreceptors and the ganglion cells. That ok? With both you AND Rufus? PG


In looking over the sylabus, I find that I am primarily interested in various aspects of the mechanical processes of information retrieval. For instance, why do certain mnemonic techniques work better than others? Is there a particular format which the brain handles more easily than others? If all of the various structures contribute small portions of their information, where does the final output manifest itself?

I would also like to learn more about the I-function in the context of self-awareness. Specifically, which system are involved and what each contributes to the holistic sense of being. What sort of studies are currently underway that address this aspect of behavior and how such a system originated?

Your first question is a nice one, and follows indeed from what we've learned. It SHOULD be easier to learn some things as opposed to others, and is. The question is why? (for the future, I'm afraid, though maybe that's a good thing since it gives you something to work on). As for the I function, THAT we'll take more about. Holistic? Maybe, maybe not. PG


I realized recently that I never mailed you a mini-essay two weeks ago. I went home that weekend from Thursday until Monday. I elected to do zero work during this time and instead to enjoy the Easter holiday and the company of my family. I could not, however, escape from learning. When I sat down in my optomitrist's waiting room Friday afternoon, I had a choice of reading _People_ magazine's Academy Awards issue (great for Hollywood gossip!) or _Time_. After a quick glance to see what my favorite stars wore to the Oscar's, I picked up the news magazine. The cover-page article's topic appealed to the neurobiologist in me: Can computers think? And if so, what's so special about the human mind?

"I should read this! Professor Grobstein will love it!" I thought. I opened the magazine, but the page I opened it to caught my attention and I never got back to the cover-page article before it was time for my appointment. The article I opened up to was about a pair of conjoined twins. These two identical 6-year-old sisters each have their own head and and neck but share one torso, one pair of arms, and one pair of legs. They each have their own spinal cord and distinct nervous systems--one feels everything on the left side of their body and the other feels everything on the right.

I found their situation extremely amazing: they can walk, run, clap hands, etc., just like a one-nervous-systemed person. Anyone who has ever taken dancing classes or run in a three-legged race knows how difficult it is for two bodies to operate together so fluidly. No corallary discharge signals are telling one twin's brain what is happening on an entire half of her body, yet she and her twin can still funtion as a single person!

This also reminded me of the qestion I asked in class (and that someone else asked in an essay) that was never answered: if identical twins have identical experiences, would they have identical nervous systems?

Thanks. I noticed the article too. Interesting situation indeed. And I haven't forgotten your twin question. We'll get to it. PG


I am not sure what the topic was for this week, so I will just write about reality. I am returning to this issue, since I need to reexamine some of my earlier ideas in light of what we have talked about in class. First, I want to return to art and math. In one of my previous essays I talked about abstract art and higher-dimensional spaces as representations of the ÒrealÓ reality. I found it fascinating that there existed something bigger than us, something that we can not perceive. Our classes made me realize that indeed, we do not know whether something like fourth dimension exists. Mathematics conceves of the fourth (and higher) dimension as a generalization of one, two and three-dimensional spaces which we are capable of perceiving. We can create representations of four-dimensional objects in 3d, analogical to a picture of a 3d object in the plane.

For example, a cube in 2d: [Picture not available]

However, this analogy does not do much more than take our perception of the three-space anduse our logic (based on perception) to generalize. Therefore we can not say anything definite about the ÒrealÓ reality. In this sense, art is a good representation of it. It expresses our imaigination of reality, but does not make definite claims.

Now, is our reality more real than the ÒrealÓ reality? Yes, since there is nothing real about the ÒrealÓ reality.

There is only one definite reality, and that is each individualÕs subjective reality.

Then, there is something like probability of collective reality, which is based on correlations of different individualsÕ perceptions (i.e. we are able to identify the light reflected from certain object and to ÒrecognizeÓ that object). We seem to perceive space, time, sound and other sensory input in similar ways. For example, we identify the same sound as pleasant or unpleasant, high- or low-pitched, etc. However, we can not be sure that these correlations are perfect.

It is interesting how my understanding of the world has changed in several weeks. When I wrote my last essay on reality (before we brought up this topic in class), my understanding of the issue was very intuitive. Things make much more sense now, when I learned about lateral inhibition, and the sensory systems in general (maybe you should cross-list your class with philosophy...).

Thanks. Philosophy of course is intertwined with (and probably has its origins in) natural history. Which is to say in "trying to make sense of things". I'm glad some of this is getting across and impacting. Indeed, as far as one can tell from brain research, everybody's reality IS fundamentally private, but the commonalities of private realities suggest there exist external things with which we all commonly interact. Which in turn suggests enormous benefits in sharing private realities. PG


During the past couple of the months, we truly have covered a large spectrum of information. Obviously we can not learn EVERYTHING about neurobiology in one class, or in ten classes for that matter, but I think I have learned a lot about what goes on in my head.

There are two main questions that still bug me however. Why and How do we have emotions? There must be some reason for them, because we have so many, varied emotions, but they seems to only serve as a detrement. What is the purpose of grieving over a lost one, or feeling frightened? It seems to me like it could only be bad. And where do emotions arive from? It seems like there is no external stiumuli, so it must originate within the body.

Another question that I am curious about is where and how does the brain store information. There is endless information that each of us remembers, and it must be kept somewhere. Where is the library that holds of of this? And if action potentials are nothing more then permeability changes, how can the information be kept? Man can store a seemingly endless supply of information, but how? And how does the brain find the requested information so fast, when there is so much info to weed through.

I look forward to maybe getting these answears, ------Dan Feinberg

Thanks for accepting in advance that we don't have time for EVERYTHING. We'll talk a bit about how the brain stores information, but not enough to answer your more specific questions. That's a whole field of very active study in its own right, and I can point you in some directions if you're interested. Emotions raise some more general issues, which we will also talk more about. If we don't do enough of that, there's a very nice recent book called Descartes' Error, by Antonio Damasio, which you might want to read. PG


At this point in the course I feel we have covered most of the aspects of the original "boxes within a larger box" analogy we used to describe the nervous system as a whole at the beginning of the semester. We have accounted for in adequate detail what sort of processes involve the input into the box as well as the output from the box and how output signals can act as input signals as well. The approach that has been taken has been quite helpful in understanding the material because each concept was approached in a slightly more theoretical manner before it was explained what actually happens biologically. One aspect that I feel should be covered in a bit more detail is the concept that input signals can come from within the box. Much of this is attributed to what we have designated as the "I" function.

Is there really so little known about the I function that it can't really be explained biologically? It just seems that the I-function plays such a large role in our everyday behavior that it deserves a bit more coverage. Perhaps there are some modern theories on what defines the I-function and what sort of responsibilities it has in the overall scheme of the nervous system. There are some theories that the I-function box is perhaps the Master or Main box, because if given enough development it can control or generate input to parts of the body and nervous system that were up to this point considered independent of the I function (control of autonomic NS, heart rate, body temp). Another question that is closely related is what we mean by the mind and is it the same as the I-function?

Fair enough. More than happy to go in this direction for rest of course, though they are a couple of more preliminaries to cover first. Have already suggested that I-function is less a part of behavior than one usually thinks, and will suggest that, important as it undoubtedly is, it is not in fact a Master box. Yes, mind/self re I function an interesting and approachable question. PG


Our initial assertion was that behaviour is the brain and since no two people are alike in this world, it follows that there are no two brains that are alike either. Since the start of the semester we have learnt a lot about the structure and function of the brain. The brain is considered to be a box which consists of smaller boxes, the smallest being the neuron which we have studied in detail. We have studied action potentials, patterns of activity, central pattern generation, reafferance, corollary discharge signals and perception through studying the visionary system. All of this has highlighted a number of important principles that can be applied to explain many behaviours. We learnt through the course of the semester the importance of intercommunication between the many different boxes within the big box; that much of behaviour has its origin within the nervous system and that the nervous system stores an incredible amount of information. Slowly, it seems that the pieces are coming together but I still find that there are a number of pieces that have yet to be explained.

I still feel that there are some more fundamental principles that need to be addressed and explained in order to apply them to other behaviours. The "I" function is still a source of mystery to me - how it operates, interacts with the rest of the nervous system and the extent of its role in behaviour. Each individual has a different personality which makes them individuals; different faiths, beliefs, talents, hopes, emotions, intuition, they undergo different changes and maturity and so forth. I still do not find myself capable of explaining all of these in terms of what we have learnt thus far in the course. We are all similar in the sense that our body structure is similar, our organs have the same functions and so on, what makes our nervous system capable of making us so different from each other? I realise that a large part of the reason why we have to be different is for evolution but are we different because of our nervous systems, our genes - what?

Fair questions, and we will talk some more (and some more explicitly) about them. More about the I-function is part of the (an) answer, but not the whole thing. Remember that it is not only our nervous systems which are different in different individuals but also other organs as well. All have same GENERAL functions, but lots of individual variation. Because of ...? And what causes ...? We'll see ( in part). PG


At this point in the course I think we have an understanding of the general functioning of the Nervous System, and also some explanation of different behaviors. The dependence of behavior on the actions of Nervous System, and the interconnections between the two appear clearer than before, yet we didn't talk about the behavior as much as I thought we would. May be a partial reason for it is that it is unnecessary to distinguish and clarify the borders between behavior and the actions of NS. We went over many examples encompassing both brain and behavior, and I think that studying them together really prevented a lot of confusion for me, as I tend to center on small things and sometimes miss the bigger picture. I also expected the course to be a lot more anatomically detailed, and I'm happy it wasn't, because that would have complicated concepts we studied to the extent where I, for one, would have been unable to sort them out. On the whole, I think, this course was a good introduction, not overly detailed, yet sufficiently so as to provide a basis for further study.

I wish we could have spent more time on the subject of how thoughts originate, and how we think. I'm also curious about dreaming, especially pictures we see in sleep, and the role that visual cortex plays in their creation. We kind of ignored the phenomenon of hearing, and is it in some ways analogous to the way in which we see? Also the interesting distinction between the involuntary actions of NS (those we can't control ) and those things we do have some control over, was made in relation to a couple of the phenomena in NS, yet not in association with the process of seeing . Is it still relevant ? We still have to put all of the things we learned together, and then we didn't do anything with memory, recognition of places, people. May it would help if we could approximately trace all the actions of the NS when we read, for example.

Indeed, didn't talk about "behavior" in terms of formal analyses, but, as you said, did talk about what most people mean by behavior ("folk psychology"). Am glad it works for you. Do agree though that there are some important things left to talk about, including voluntary/involuntary distinction (yes, its present in vision, remember the blindsight experiment I described?), and dreams, and the origins of thoughts. Will still try and get to those. PG


In my opinion this course has been much more interesting than I thought it would be. There was less memorizing of anatomical parts (and their functions), but more application to behavior which I thought was more useful and more effective in learning the functions (and some important structures), instead of straight memorization. In addition, as a result of this course I've had some great philosophical discussions/debates with my friends about how the nervous system IS behavior.

I realize that we only have four class periods left, so we won't be able to discuss the vast amount of material out there on the nervous system and behavior that we have not yet covered (it would probably take a number of lifetimes anyway). I was wondering whether we have learned everything to be able to answer the question about the identical twins. But more specifically, my original question was about identical twins living in the exact same environment, such as a bubble. Also, are we going to be able to answer why the right side of the brain controls the left side of the body and vice versa? (Is there an answer?

Furthermore, I don't think I'm completely clear on the I function. Is it only related to consciousness? For example, when people say, "I felt like it..." In addition, I was wondering if we were going to talk about memory. (And we probably will not have time for this, but for my own knowledge, do dreams contribute to our behavior in any way? If so, how?)

Hmmm. YOU want to teach this course next time? I'm VERY pleased the course has engaged you the way it has. No, we're NOT going to be able to explain the left/right problem, but its one you (like me) can keep (hopefully productively) worrying about. On the other hand, we WILL talk about the twins (I promise), and about the I-function. AND a bit about memory, and yes, about dreams. PG


I was thinking about the optic nerve and the possible reasons why it might crisscross.

One can approach this problem from an evolutionary perspective. Then, there exist two possibilities. The first is that it conferred no advantages on an organism, but at the same time was not maladpative. It was just one of many plausible solutions and arose by chance.

The other possiblity is that it did confer some sort of advantage. If someone could describe the advantage, this would win them the nobel. The only possibler conjecture I have is this. Crisscrossing of the optic nerve adds more distance to the neural pathway. If a straight line existed, the net distance would be shorter. Perhaps the distance added by this crisscrossing corresponds better to the demands on the nervous system by the outside world. Maybe an exhaustive quantative analysis of nueronal speed and distance and reflex time could demonstrate this. We always tend to think that faster is better, but maybe, the distance allowed by a crisscross suits us better.

Just a guess.

Would need to be fleshed out a lot. And could equally achieve distance by making nerves longer without crossing them. More generally, there are actually THREE reasons why things are the way they are, not two. In addition to random event but not maladaptive and random event which is adaptive there is the possibility that certain forms are inevitable given random interactions of particular kinds of elements. Is possible the crossing phenomena have this character. PG



I would have to say that since we approached the sensory systems and how input affects the nervous system, I have become fairly comfortable with the issues we have addressed so far. It is basically impossible for us to have a complete understanding of how we "behave" since scientists discover new things everyday. I know behavior and what makes each person an individual is something that I will always question, even if science can supposedly pinpoint to what gene each response can be attributed. In general, a lot of behaviors occur in response to seeing something. The visual sensory system is probably the most used, especially as a first repsonse (except for those who are blind). Though reality is not exactly what is lying/reflected on the retina, it still remains the reality for that person. Therefore, a great deal of behavior due to the so-called "I-function" remains hazy; personalities still cannot be explained.

I do wish that while we were learning about the sensory systems that we had covered how the nervous system actually allows or causes taste. I realize that it is a sort of input that is used only for certain occasions (and thus probably not as important), but I have noticed a trend wherein the nervous system of each person can tolerate certain degrees of spices. I think it would be fascinating to learn about why some people respond differently when eating certain foods. I realize no two systems are exactly alike yet why are there what are referred to as "supertasters" for whom the taste of white rice can be a perfectly seasoned meal. Also are there patterns that exist for enjoying a certain taste before someone has even tried the food? Or would it be more likely that the nervous system is aware of sourness and is already more likely to dislike that? Another aspect to taste, I would like to consider is how much the "I-function" may or may not play a role.

Taste is indeed interesting, and there is a lot of work on it (which we won't get to talk about but I can give you some starting references for). The I function and personality we WILL talk more about. And about another thing you mentioned. Yes, who one is remains hazy because we don't yet understand enough about the brain. But is also remains hazy (and always will) for a second reason we'll talk about: you make it up as you go along, and the better you understand it the more it changes. PG


At this point, we have a good understanding of movement, vision, and the general workings of neurons. From this base of knowledge, we can speculate about other sensory systems. What we have not focused on is the effect of internally generated signals on behavior. By looking at the hypothalamus and the pituitary gland, we can learn about the regulatory effects of hormones on the body, and their impact on behavior. For example, we have not investigated the role of hormones in the sexual functioning of the body, both in terms of development, and in terms of sexual behavior. Human sexual behavior is of interest because it is affected not only by chemical signals within body, but by the quest for pleasure. We need to determine what pleasure is and where it comes from.

From the hypothalamus, we can also learn about sleep and feeding behavior. To what extent can we control our sleeping patterns, and to what extent are we just fighting a losing battle in trying to ignore fatigue? Feeding behavior is also quite complicated in human beings, in that it is an interplay between chemical signals and psychological ones. It is for this reason that it is impossible to create an accurate animal model of anorexia nervosa, for instance. How much of eating is psychologically driven? How rigid is the set point - are dieters also fighting a losing battle? Are hunger and satiety effected by mood? In addition, we need to talk about memory, since a large part of our behavior results from information we have stored in our brains. How is it stored? How do we learn, on a neuronal level? Are memories always real, or can they be imagined? What "memory" are we born with, and how does this explain instincts?

The only problem is that we only have several more classes . . . .

Yeah, that's the problem. But we MUST talk a bit about hormones and similar things (and will), and at least a bit about memory. Nice questions, all very much worth pursuing and, I think, pursuable given the things we have (and will still) talk about. PG


There is not one area in the brain that produces the picture in our head. This\seems to be one of the themes of this course- the various functions of the nervous system are localized and fragmented with small boxes doing different things simultaneously. It is difficult to comprehend that a complex behavior such as the production of the picture in our head is not controlled by one part of the brain. Prior to this class, I assumed that the majority of behavior is controlled by what you term the "I" function box.

If there are over a billion neurons in the nervous system, how can there not be a mechanism which coordinates all their activity? Take the analogy of a countrywith a billion people in it. It seems that it is more efficient and the people are better provided for- in terms of education, healthcare and employment in a centralized, socialist government verses a laissezfaire political enviroment. Wouldn't it more effective if the nervous system had such a mechanism? Does thenervous system accomplishes daily, complex behavior in the absense of the "I" function? I am still not completely clear of the exact method by which the boxescommunicate with each other. How is the final decision made out what picture get seen in my head?

Bingo. There INDEED is the question (are the questions). We will, I promise, look at the question of who makes the final decision as to what picture gets seen in your head. And no, it won't be the "I-function". And yes, this does relate to the broader question of whether systems can be organized without a central authority. There is an explosion of books on this subject, both highly academic and popular. Out of Control, by Kevin Kelly, is a not bad example of the latter, with a bibliography that can be used to get into the more academic literature. In any case, the nervous system seems indeed to be a "complex system" of the non central authority type (most biological systems are). Which does indeed in turn raise some questions about any presumption that social and political systems necessarily must have a centralized authority. PG


Well, as far as the things we've covered go, it seems like we're really behind in what was scheduled on the syllabus. I guess somewhere around spring break? But I really think that that's good, because otherwise it would've just been too much information, and we all would have been overwhelmed. And it must be good b/c it means that everyone was really interested and focused on the issues we were discussing. I wonder how much of the syllabus we would have covered if no one had asked you questions. Speaking of questions, I have a whole lot of questions to ask you. I don't know if I should ask you over email or if I should make an appointment to come in and see you... Anyway, I have a big long list of all of the recent things that I'm not crystal clear on, or that just popped into my head during lecture.

As for what we should be covering next, I think we should discuss the other sensory systems and how they're similar to the visual system or not. It just seems like we spent a lot of time discussing the visual system and the implications that everything we discussed before it had on the visual system. So I guess as far as our goals go, we pretty much succeeded. Going from a basic question of 'What is behavior?' to a general model of the nervous system to a much more specific model of the nervous system, to lots of mechanisms the nervous system uses to create or interpret behavior, to showing how a sensory system produces behavior using all of the information we'd previously learned, is basically a good way to go about achieving this answer to 'what is behavior?'. All I'd like to see now is an expansion of that answer to other systems. See you in class. Jennifer.

Indeed we've slipped from the syllabus. Thanks though for the thought that it may be better this way; I've learned a lot too from our conversations. And thank we've got some useful general principles which people can use. Instead of going on to that, how about a few more general principles, related to things toward the end of the syllabus? PG


In the final weeks of class, I would like to attempt to address several issues. To begin, I feel that there is a need to acquire a more holistic understanding of how the multiple systems of the body interact to create a "complete" sense of reality. I would like to gain a more in-depth understanding of the manner in which the auditory and visual systems, for example, are integrated to achieve the final picture. If light and sound travel at different speeds, how are the two experiences integrated? I would also like to explore memory, learning, and the manner in which one's expectation or anticipation of an approaching event works to "color" one's experience. I do feel very satisfied and pleased with the course that this class has taken and I have learned a great deal!!Thank you.

Thank YOU. The course of the class is your influence as well as mine, and I too have been pleased by it. The integration of the boxes remains a major issue, and we'll talk a bit more about it (though not enough, partly because its only recently been able to see it as a major issue). And yes, we'll deal a bit with memory and its interaction with other influences on expectation. PG


So far, we have assessed the nervous system as a collection of interconnected boxes which communicate via patterns of action potentials. We've seen how these boxes can influence one another based on properties that are common to all of them and some unique properties in some individual boxes. We have begun to understand color vision as a function of these boxes, thus making a leap between the basic interactions between the smallest of boxes to the explanation of a relatively complex phenomenon. We've seen how principles applied in visual phenomena are similarly used in other areas of the nervous system. We might say that the nervous system not only has at least six or seven ways of doing a particular thing, but it also uses the same way to do six or seven or many more other things.

Since we have been invited to express what we'd like to explore further, I'm going to give it a go. Something that has troubled me from the beginning is the mysterious "I function" and free will. I'm still trying to apply what I have learned about the nervous system to create a model of something capable of free will---choosing one thing over the other. What is it that governs the Harvard Law of Animal Behavior? At best, I'm having fleeting glimpses at a model of explanation in this area. I'd love to have them take a little more form before we end the semester.

Gee. Exactly what *I* wanted to talk about too. Thanks. Let's see how it goes (and yes, same way to do six or seven different things). PG


In our last few (two?) weeks of class, I'd love to talk more about neuropeptides and how various drugs are able to resemble naturally produced neurotransmitters and some other interactions of these drugs with the N.S.

Will do SOME of this, but probably not enough for your taste. Earl Thomas teaches a course in psychopharmacology (as you probably know). Hopefully, we'll give you at least some framework for continuing interest. PG


I think we have reached a good understanding of the way the nervous system works but we have not talked about many specifics. We discussed vision in detail but did not learn about many other senses or how input from more than one type of receptor can combine to form one output. It seems that many responses would be the result of a combination of inputs.

Fair enough. Yes, need to combine inputs. Will touch a bit on that today. PG


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