An ongoing conversation on brain and behavior, associated with Biology 202, spring, 1998, at Bryn Mawr College. Student responses to weekly lecture/discussions and topics.
If brain=behavior, then things learned about nervous system structure and function might be expected to change how one thinks about behavior. In this respect, how significant is or is not a better understanding of such cell level processes as action potentials and membrane potentials in general? If such understandings have changed the way you think about behavior, explain how and why. If not, discuss why you think they might or might not in principle do so.
(As in weeks past (and future), students were free instead to write instead on any other subject that struck them as particularly interesting during the week).
Perhaps what struck me most here was in looking at the larger picture. I am a firm believer in the larger picture. I like the idea that behavior is not caused but allowed to happen. I immediately thought of such things as panic attacks and disorders, general anxiety, depression, and maybe even compulsions. Do people just have an inhibitor in their nervous systems that, if turned off by a chemical imbalance or environmental trigger, will become activated, causing panic, depression, etc.? Obviously, it is more complex than that but it is a new way of seeing illness. If this was a widespread interpretation of the nervous system, I can see it having a huge impact on the stigma attached to certain illnesses, particularly mental illnesees.
So, there you have it. Now, if we could just find out what this inhibitor that affects paraplegics that can't be discussed in mixed company is....
Not bad for not being riled up. At least two ideas that one might productively spend a life time doing some looking into. And interesting how that comes from going back and forth between details and "larger picture", no? PG
One of the most interesting topics is that there are neurons that constantly have a high concentration of sodium and therefore are constant generators of action potentials. We can relate this to the brain=behavior discussion because this insight helps to explain why humans can have behavior (output) with no apparant input.
A particularly relevant example of this is the pacemaker cells in heart. Just think if we had to consciously "think" about making our heart beat all day, every day as long as we lived? As absent minded as I am at times, I certainly do not think I would survive very long!!!
Furthermore, another topic that sparked my interest was the fact that since synaptic transmission is the way that one signal is passed from one neuron to a target, neurons are intimately connected and can have great influence on one another. Signals can be stopped in their tracks, slowed down, or even stopped simply by the influence of another neuron. It makes me wonder if signals can actually be "changed" by other neurons through synaptic transmission? It also brings to mind that some behaviors may not be caused by anything, but may simply be allowed to happen!
An interesting area to explore would be to study what suddenly is allowed to happen by the nervous system when a person's spinal cord is damaged or severed.
Lastly, I have been struck this week by the enormous complexity of the human body! It is no wonder that when a seemingly minor health problem may arise, that because of the body's interconnectedness, it can rapidly become something major or even life-threatening. As a future physician, it helps me to think about treating the person as a whole system, and not simply to look at the specific problem by itself.
Several interesting points, including the generalities that parts can work by themselves and wholes are lots of parts which, for some purposes, need to be thought about as wholes. Remember its not the sodium "concentration" but the sodium "permeability" that can lead to spontaneous generation of action potentials. PG
if brain=behavior then whatever makes our brains makes our behavior. I believe that the DNA sequence which was uniquely pieced together from our parental gametes is directly responsible for the such characteristics as hair color, size, predisposition to acquire certain diseases, and many other physical characteristics of our lives. It seems I can not escape the logical extension of these traits to include the actual "wiring" together of our neurons. is it the basic connections of our nerve cells which determine our behavior?
I hope not. I know twin studies are often referenced when discussing issues such as these, and that they are often full of frustrating confounding variables, but I would like to relate a short story of some twins I know. Two of my cousins are "identical" twins, one was born, however, with a misguided esophagus such that he could not eat. as a result he underwent many operations over the first nine months of his life. this extra stress and attention seems to have had a long lasting effect. he is now smaller and more reserved than his gregarious brother. Throughout the twelve years of their lives the smaller one has been give more babying, more reassurance and protection by their parents and everyone they come in contact with.
thus, they have experienced significantly different environments growing up, even though they have been raised together. I'm not sure where to go with the argument now, but it sure seems like a good one for environmental effects on behavior.
long term environmental stimuli which tend to elicit one type of behavior seem to override whatever genetic influence there may be on ones behavior.
how, then do I explain the amazing examples of slaves, prisoners, and the like which have survived horrendous conditions seemingly coming out stronger? I don't know....
I am hoping to come to the conclusion through this course that our behaviors are indeed determined in the present tense, rather then predetermined through means none of us have control over.
That would indeed be a satisfying place to get to, and I think we will. Not only because its satisfying but also because its the "best summary of observations" or "trend of the evidence". Yes, of course, genes INFLUENCE neuronal connection patterns (among other things, which also include permeabilities). No, they don't DETERMINE them (as is evident from a variety of things in "identical" twins, who do have the same genome but differ in general in a variety of ways, including, for example, finger prints). The question is, of course, what are the OTHER influences, how may are there, and how do they operate? We'll talk a lot about this as we go. For some foreshadowing, you might take a look at Serendip's section on Genes and Behavior. There's also a new book on twins, reviewed in the NY Times Book Review last Sunday,which I haven't read but looked interesting (Twins and What They Tell Us About Who We Are, by Lawrence Wright, John Wiley and Sons, 1998). Its on a list of books about twins maintained by Twinspace, "the website about twins", which might be an interesting window to further exploring that particular phenomenon. PG
Or at least gives us some underlying mechanics to increase our "faith" that this is so? You're right, though, that the "mechanics" make it a bit easier to understand (accept?) why things feel different and different times and why we act/react differently to different things. Do the mechanics help in other ways? PG
It's hard not to get caught up in the complexity of behavior. Think about taking a drink from a glass. This is a pretty simple behavior, and it is easy to understand how the cellular level processes of action potentials function to produce a physical manifestion of themselves in the lifting of the glass and the swallowing of the water. But now, think about the behavior of falling in love. There just has to be something else there besides concentration differences and sodium and potassium gates. People have been trying to understand and explain the experience of falling in love throughout all human history. This behavior just cannot be explained away like taking a drink can be explained.
So, where does this leave us? I don't think that explaining behavior in terms of cellular processes makes us inhuman, unfeeling machines. Rather, I think that this understanding adds more complexity to the human experience. It also gives us a solid basis for explaining simple, routine behaviors. But I'm still waiting (like a lot of others) for that "something more" that makes us who we are.
Fair enough. But ... does thinking of drinking a glass of water in terms of concentration differences and gates really "explain it away"? One is still drinking the water, and what is involved is, as you say, a dauntingly complex and orderly set of ion movements. Maybe "falling in love" is the same thing but even more complex? It doesn't get "explained away" either, just recognized as a set of ... ion movements, which is so complex as to achieve all of the extraordinariness of falling in love?
By the by, its February 14. Happy Valentine's Day everyone. PG
Taking the nervous system into account means being able to give it some of the blame! In some cases of the disorder amblyopia, displaying a severe loss of vision, untraceable to disease or deformity in the eye itself, a malfunction in the nervous system is to blame. The cellular processes leading to this dysfunction are still being researched.
These cellular processes also account for conditions such as addiction. That the neurons in the brain can become tolerant of certain substances and can adapt to the drugged condition is surely something significant as a reason to understand the cell level processes. Receptors on certain (LC) neurons respond to opiates, inhibiting the neurons' firing, and eventually becoming tolerant. Understanding how this is possible can help in finding a way to rehabilitate opiate addicts.
In such ways, the comprehension (to the smallest detail) of the properly functioning nervous system can do a world of wonder in diagnosing and treating an organisms' disorders.j
Is good point, similar to the thinking about epilepsy with which we started the course. Studying the properties of neurons does, in a wide array of cases, turn out to yield insights which CAN be used to influence behavior (for good and, perhaps, for less good, depending?). And that, of course, is both an argument for the importance of cellular level processes and for the more general brain=behavior proposition. On the other hand, it also generally turns out that behavioral phenomena can be influenced but not fully controlled by cellular level manipulations (anti-depressant drugs, for example, work for some people, sometimes, but not all people all the time). Any idea why that is so? And what it implies about both the relation between cellular level phenomena and behavior and the more general brain=behavior proposition? PG
I was reading the other entries, and my attention was caught again by the notion that much of our behavior is the result of things being "allowed to happen". It set me thinking along the following line: if abnormalities, malfunctions, etc., are the result of the failure of excitatory/inhibitory postsynaptic potentials to create the action potentials necessary to prevent such malfunctions, then not only might we have a clue as to the causes of some types of mental illnesses (as stated above), e.g. OCD, but also a potential explanation for the mental deterioration that seems to accompany aging.
Seeing my grandmother getting old and losing more and more of her memory, becoming increasingly delusional, I've wondered, as I'm sure many of you have, whether this is inevitable. Are her neurons undergoing a process of entropy, moving towards an ever increasingly disordered state? If so, then why is it that despite her inability to remember something I said just a few minutes before, she can recall with clarity and precision scenes and experiences from her childhood?
I remember reading in this wellness/nutrition healthletter that old people don't think any worse than their younger counterparts, just that it takes a bit longer; that if you give them time, they are quite as able as someone half their age. It also said that to counteract the effects that aging has on one's memory, one should keep one's brain active, do crosswords, et al. Does this mean that if we continue to stimulate our brains, send input to our neurons, that they keep working better? Does input to the brain become increasingly important as we grow old, or is it that it is just as important at any age and that it tends to decrease due to our decreased activity?
Funny how thoughts tend to come together...going back to Jeremy's essay, in light of what I've just written, it seems that our behavior (->activity) does have a rather important role in determining our lives. Neurons create certain involuntary behavior and allow for other potential behaviors; whether or not/how we make use of or choose among the opportunities presented to us by our biological make-up in turn impacts on the functional elements, and so on, and so on...I think we need to stop thinking in hierarchies and straight lines and take the circular route. Or maybe spirals...Hope this makes sense to whoever takes the time to read it--I have a tend to think as i write (but let's leave that for another time).
Wonderful links to your own experiences, others thoughts, all in and around the course material. Very gratifying, just what the forum is supposed to make possible. Many thanks. There's a lot of interest/action these days on the aging phenomenon, which is still pretty poorly understood. See this Sunday's New York Times magazine for an interesting and provocative article on the ongoing development of "memory enhancing" drugs.
Along more conceptual lines, you're right of course that there is an increasing understanding that things in biology (including the brain) have in general multiple rather than single causes (I remember when this thought first hit me, in the context of some research I was doing more than fifteen years ago, and actually cowrote a paper on the subject, which isn't on Serendip but perhaps ought to be). And that there is a general "loopiness" in causation, so that things which affect other things are in turn affected by them. With the bottom line indeed being to suggest there is plenty of "room for flexibility and growth". We'll try and make all that more concrete for brain and behavior as we go on. PG
It is no wonder that with all of this input, our senses often feel bombarded when we encounter another person to whom we are attracted ó if only for biochemical reasons. This onslaught of the senses is universally identified by medical symptoms: sweaty palms, racing pulse, a "sick" feeling in the stomach ó all possible chemical reactions, caused when one comes in close contact to the beloved. There is no cure for the common crush. However, it is possible to identify and explain its symptoms in an attempt to do what humans have been attempting to do for many millennia: define the incredible emotion we call love.
Nice addition to the set of thoughts on this subject (will decline to feel incorporated into class of ... having "few practical attributes"). To which we might also add some of the above conversation: behavior has an enormous number of influences, few "determinants" and some earlier conversation: every brain is different. So "has been proven" is a little strong and a little sweeping. On the other hand, both odor and symmetry are unquestionably factors of significance in a significant number of people. I'm not sure I'd want to deprive people of the experience of "the common crush", but maybe knowing more about some of the factors involved would help people avoid some of its sometimes less satisfying consequences? PG
In Love: is it really all in your head, brain scientist Karl Pribram talks about the fact that "apart from individual psychological influences, there are a myriad of overlapping brain signals and processes that are involved in love and sexual attraction." His theory involves 3 specific regions of the brain in addition to pheremones: a steroid regulating hypothalamic portion which is located in between food and temperature regulatory centers, the amygdala which is involved in producing the symptoms of someone "in love" such as distraction, heightened physical sensitivity, and apathy towards things such as eating and drinking (Pribram), and the frontal lobe which is associated with "motivation and commitment" (Pribram). The pheremones are said to "stimulat[e] arousal centers in the brain" (Pribram).
Pribram is quick to make the distinction between being "in love" and being "loving." Being "in love," he says, involves being passionate and this "in love" state is associated with a unique brain chemistry.
What this scientist has to say makes a lot of sense to me. Especially because his ideas do not exclude other factors involved in "falling" or "being in love" such as "availability, feasibility, mutuality, compatibility and commitment" (Pribram).
Despite the involvement of other factors, the views outlined still strike me as too reductionist. I feel uneasy about the idea that love can be explained away; although, I do not reject the possibility. It just seems that if the above is true than it may be possible one day to plug yourself into an equation on a computer (i.e. 2 * constant + you = your love), push a button, and voila...out comes a description of your ideal mate. I think a lot of the fun is in exploring and through that learning what works for you and what doesn't.
The link is actually to an article quoting Pribram, but neither less nice nor less relevant for that. Pribram though may be thought of as in the "fewer practical attributes" class (see above). Helen Fisher, mentioned in a recent Inquirer article, is an anthropologist who actually more directly involved than Pribram, in thinking about love in relation to the brain. Regardless of where it comes from, the story indeed seems to be that (as above) there are lots of factors in "love", not just one. The question is, as you say, given THAT, is there STILL something too "reductionistic" about the whole approach. Does it "explain away" love, and if not, why not? I like your way of looking at the problem: could one measure everything and come up with "ideal mate"? Probably not, since the "exploring" and learning probably changes the definition itself. So we're back to process (see above and last week) and, perhaps, to the brain? PG
The ball-throwing example is one of the simpler actions. It is much more difficult to explain the process by which memories are stored or dreams are experienced. Evolution has dictated the development of a bafflingly intricate and complex system to form human behavior. We are left to ponder, open-jawed, the seemingly abstract, spontaneous creation of thoughts and actions formed merely by the flow of ions with a concentration gradient. Truly spectacular.
Spectacular indeed. Both as the outcome of a process (evolution) and as the process itself (the details of what is occuring at any given time). And, of course, as a process (what is occuring now) which is part and parcel of the larger process, hence presumably both reflecting it and altering it. From which several general issues emerge needing to be explored in the specifics. What achieves the "coordination"? What properties and interactions are needed to account for the outcome at any given time? Is now the end of the process or only the particular stage we happen to be in? What role do we play in what happens next? And what are the consequences of whatever role we play for that? Are the concepts of neurotransmission enough to approach such questions or is something more needed? PG
Love is probably one of the most obsessed over "feelings" which is definitely not a bad thing. After skimming through the previous responses the "love" debate caught my attention and I began to thing about other emotions.
Why do people cry? Or how? And why all the other things that go along with it. Sometimes there will just be tears, other times loud sobbing, sometimes there is the chin quiver-etc. My actual question is why do tears go hand in hand with emotion--people cry when they are happy, sad, scared, mad, etc. and sometimes they don't. Going along with the equation that brain = behavior, any action is caused but neurons firing. So that is what causes tears. In that case the conclusion can be drawn that the "feelings" neurons are associated with the "tear" neurons- but why? Why do I feel like crying when I see a sad movie? Is it a necessary reaction? Certainly not necessary for survival- crying in the movie theater is not going to save my life or someone else's life - like the actor in the movie. In this case tears seem futile- all I get in the end is a pair of puffy eyes.
I understand the psychological benefits of crying and not "bottling up" those emotions but I can't help but wonder just why people cry. It would be fun to open up someone's skull and look into their brain. If people were cartoon characters, I would be able to follow the path of sparks to see exactly where "tears" originate.
Interesting image/thought. With modern imaging techniques its actually getting increasingly close to possible to see the "sparks" in real people even without opening up the skull. As a thought experiment: imagine that you CAN see the sparks of someone sitting in a movie theater starting to cry. Try and imagine all the possible ways it could look. Are there some of them which would allow you to say where tears originate? Any of them? PG
Fair enough. And probably as it should be (or at least has to be). Yes, because there are all those things going on behavior is quite rich. At the same time, knowing there are all those things going on requires us to try and say how they happen to be there (at least a different phrasing, maybe more useful?, of the "why do we cry?" question), and how they are coordinated (maybe, actually, the same question? if the coordination is inherent in the things being there in the particular arrangement they are?). We'll see how we do with these questions as the course goes on. PG
Yeah, I too have the feeling that people sometimes learn things because they're told to and quickly forget them (and share your suspicion that there is some conspiracy to do this "to make students miserable"). Hence the question. And I like your answer. Yes, at least some behavior level questions get at least partial answers from looking at cells. Yes, it can help with mental health and other clinical issues. But, most importantly for me, it does seem to "make it easier for us to understand and accept others' behavior". And our own. Wonder why that is? In terms of neurons? PG
I think it is very significant to understand the details of action potentials in the cell because in order to comprehend behavior as a whole, we first need to understand the parts that make it up. Cells and action potentials within the cells are the little parts that make up how we react to things and situations around us. Potentials are key to our behaviors.
My thoughts about behavior in general haven't changed much, but I feel I understand at least the beginnings on how behaviors are formed. I find it interesting to think of information flowing through our cells in waves of permeability. Since the signals are not electrical, it takes time for signals to travel through the body. This may even be an acceptable reason for why people trip over things or are unusually clumsy- it may just be because their nervous system had a considerably longer time delay than others in reacting to obstacles. Or perhaps, they could just be absentminded (of course I'm not talking about myself).
The thing that both interests and scares me is the fact that all the action potentials are the same throughout all neurons. The only difference lies in which neurons are carrying the signals and where they are being carried to. If by some freak chance there was an accident and someone's sensory connections were confused, the person would never be able to actually see with his eyes or hear with his ears again. They would forever "see" thunder and "hear" lightening. I think this is something to be concerned about, but I'm not even sure if this could actually happen though.
There are indeed known situations in which there are easily observable alterations in "wiring patterns" in the brain. Ocular albinism, a genetic condition, is one such case. If one accepts that every brain is different, one might also suspect that, to one or another extent, everyone's connection pattern is a little differenet and so everyone to some extent sees/hears things differently? We'll talk more about this, but it is indeed another place where knowing something about cell properties might help to better understand one's own behavior and that of others. PG
Considering brain function in light of cell level processes is definitely crucial. A simple proof is that as students we need to remember that the brains we rely on are made up of cells need nutrition and rest, and so we need to eat and sleep. The most obvious examples of the significance of understanding neurons involve brains which are different from the "norm." Attention Deficit Disorder, as controversial as it may be, should represent a step forward for medicine and psychology in the long run. By discovering the biochemical basis for childrens' uncontrollable or excitable actions, the way we view their behavior has been changed. We may hopefully now deal more sensitively and efficiently with this difference.
Yes, action potentials suggest a "binaryness" of brain function. But also, yes, thats probably misleading, given that the frequency of action potentials (a continuous rather than a binary variable) is certainly a relevant parameter, and that the membrane potential varies continuously as well (in fact, some neurons use that as their inputs and outputs, without ever converting to a binary form). And, even more yes, awareness of the cells and their properties is a good reminder to eat (among other things). As for ADD, I very much share your hope that it will be "a step forward for medicine and psychology in the long run", of exactly the sort you suggest. PG
Nice point, well made. Indeed, the "same" thing may be quite different in different people, because of the extraordinary dependence of nervous system function on the details of its organization. So the "same biological process" may in fact be substantially different things when looked at at a sufficiently high level of detail. PG
Essentially then, not what thoughts I entertained about behavior changed, but my appraisal of behavior did. Definetly, for a greater appreciation of behavior and in fact all functionings of the body, an understanding of neuronal workings is essential.
Yes, the details are themselves complicated, and that's impressive. Beyond that, is it a good thing or a bad? Useful or simply confusing, maybe even unnecessary? How does it depend on what one wants to do with it? PG
What an amazing structure this nervous system of mine is! At any moment, I am taking in, processing, and responding to a multitude of sensations; but, in fact, all that is really occuring is that my sensory neurons are allowing certain inputs to instigate a domino effect of potentials throughout by body and into my brain (which, in ignorance, I am considering my central processing unit).
However, I don't find the most amazing part of my nervous system to be its abilities--I am most impressed by its inabilities. It seems to me that this system is highly faulty. I can't help but think of all the events occuring around me that I am unaware of because they simply don't stimulate the proper neurons or enough neurons. Frankly, it's scary to realize that objects that I cannot see are passing before my eyes, materials that I cannot taste are in my mouth, and touches that I cannot feel are covering my skin. Let me now revise my exclaimation: What an imperfect (but amazing nonetheless) structure my nervous system is!
Nice thought, well worth keeping in mind in general and in connection with some of the discussion above (and earlier) about whether the products of evolution "make sense". Yes, both amazing AND imperfect. Overall, as well as, in different ways in each individual. Given which, how DO we do what we do? Discover things that we can't see/taste/touch? PG
Language is THE essential component of expressing our beliefs, emotions, thoughts and dreams. It is, among other characteristics, what sets humans apart from other vertebrates - this abilty to express complex thoughts - this marvelous thing called language. Although there are permutations upon permutations of languages, dialects, slang, accents etc, the basic underlying tenet is that language is a visible and unique behavior that humans are capable of expressing. It is what sets us apart.
Thus, if one considers the biocehmical level of what is occuring in the brain - the synapses, the action potentials etc, one can gain further insight into behavior, specifically the behavior of language production and use. Without language, we would not be capable of producing such intricate thought processes in an organized manner. Let's consider the fact that I am dyslexic. What does this mean at the molecular level? Certainly, by considering what is occuring in simply writing this essay at the chemical level, one is perhaps better able to grasp the vast complexity of the brain and the ability it has to transfer such chemcial signals into the actions of our daily lives.
Certainly it is a bit disconcerting to fully embrace the brain = behavior in the most full notion, but it is essential to begin to at least consider the ramifications of such molecular intricacy translating to highly complex actions that only humans possess.
Interesting issue indeed: language and its development. The article you saw is actually available on the web: The Origins of Babble. Part of a general trend to recognize existence of abilities at earlier and earlier points in childhood. Is language really unique to humans is an interesting and still being debated issue, but certainly the extent of symbolization and creation of stable records of individual thought and experience is a distinguishing characteristic of humans. Is worth thinking about what THAT is in terms of neurons, and why we do so much of it. And yes, its worth thinking too about what dyslexia might (or might not) be in terms of neurons. My own guess is that it is more likely to have an explanation at the level of groups of neurons and interactions of groups of neurons than at the level of molecules themselves. Well worth exploring further ... and yes, important that knowing more about the nervous system in relation to behavior gives one avenues by which to explore. PG
Regrettably, what I am failing to grasp is a clear concept of the bigger picture. While on one level the explanation is worthwhile for the basic understanding of how the body works, I have not been able to make the conceptual leap as to how the conscious brain controls the body. An autonomic feedback loop where the neurons are able to "sense" changes in the environment which in turn stimulates another neuron to innervate a target makes sense. But the question that still remains in my mind is along the lines of memory. How does the brain remember concepts and pictures? How are they assimilated so that ideas can be formulated from all of the memories in the mind? Why are memories of childhood able to be triggered when in the presence of certain smells or sounds, and why else aren't they easily accessible? It is amazing to me that there are people in the world who make incredible "conceptual leaps" that they describe as intuitively obvious. What is intuition? I have seen its expression, but why is it different in one individual than in another? How does your brain continue to work on solutions when you divert your attention to other things (or even go to sleep?).
The role of the brain as the processing unit of a body machine is a wonderful explanation that definitely clears up a lot of the questions that I had earlier in the class.. I would really enjoy delving into how thoughts spontaneously arise.
I appreciate both your understanding and your impatience. Indeed, we need a base, "from which we can expand to more complex topics". And the issue is not only to develop some tools needed to approach such topics but also to reach some understandings without which I don't think we can even adequately define the topics. To put it differently, one's intuitions about the meaning of such things as "intuition" need to be dissected a bit before the extent of the problem is clear. So bear with us and we'll see if we can get some of the things you're interested in sufficiently dissected (by looking at simpler things they aren't) so that we can talk about them effectively. That make any sense? If not now, AND not at the end of the course, be sure and let me know. PG
I'm being less than brilliant this week, so this will have to do, mes amis. I'll work on coaching my neurons to operate in a pattern more conducive to brilliancy this week...
I'll look forward to next weeek, but in the meanwhile, you're doing fine. You, of course, are not the only one who had a foggy idea of little energy balls (or some equivalent). And it is to avoid such "magic" that it is indeed important to get straight what neurons can do, and what they can't. Yes, of course, demons made a lot of sense until ... neurons came along. PG
Nice set of issues, very much in the spirit of the course. Yes, indeed, this now makes more sense, but if that then what about THIS? Yes, talking about neurons and their spontaneous activity certainly makes it easier to understand that a behavior might appear without an external cause and that is PART of what we mean by "voluntary" or "self-motivated" behavior. But there is something additional in that idea which spontaneous activity in neurons doesn't seem to help one understand. Another level of complexity, as you say. So, now we have the problem straight. Think we can solve it? PG
What we have learned about action and membrane potential has definitely altered how I think about brain=behavior. It provides a critical foundation on which larger questions can now be explored. Why does a spontaneous potential happen? Do we think of these only in terms of certain homeostatic or vegetative functions, such as heart beat? Or can we apply this to all thoughts, memory, and intuition? If we know that certain behaviors happen because they are allowed to, what behaviors (emotional vs. physical) might be inhibited in all of us? How do things that once happened freely later become inhibited, and why? Are there scenarios in which we have no free will?
There was an article in Newsweek last month that talked about the neurotransmitter serotonin. The byline read "Could a single brain chemical hold the key to happiness, high social status, and a nice, flat stomach?" Clinical trials showed that individuals who had achieved a high rank within a group's social hierarchy had higher levels of serotonin in their blood than individuals at lower ranks. But it also makes the claim that "social standing has as much effect on serotonin as serotonin had on status." If we know that a chemical can have such huge effects on mood, such as depression and anxiety, and habits, such as obsessive compulsive disorder "possibly by overstimulating the receptors involved in planning and vigilance", why couldn't it apply to everything we do, think, and feel? Namely, all our behavior? This week's lecture, and this article in particular, made me think a lot about the use of drugs in therapy, and in what a vast range of scenarios it might be helpful or necessary.
Even if we knew the exact correlation between every permutation of brain chemicals and behavior we could not predict what course a life would take. So while I am definitely embracing much of the brain=behavior argument at this point, I'm still not entirely clear on how this affects, and is in turn affected by, other things such as our genes and experiences.
Nice set of connections. Yes, indeed, the next questions are do some of the principles we get from neurons apply generally? Only "vegatative" functions or "thoughts, memories, intuition"? Because, as you say, there are indeed aspects of those things which it seems DO have properties like those of neurons. And other aspects which don't? So let's start putting the neurons together and see whether we can get the additional aspects? Drugs as therapy, more generally as behavior modifiers are a very interesting and very general aspect of this question. As is, in the last analysis, would we, tracking this line of thought, find ourself doing away with free will? Or instead, perhaps, come up with a firmer base for asserting its existence (with all the attendent personal joys and responsibilities)? We won't, at least, ignore the issue, I promise. PG
It is comforting to know there is a biological explanation for most things, but it can also be frustrating. Some things will always remain a mystery.
Most assuredly so if one doesn't specify them so they can be further explored. Give us some examples of what is mysterious, and why you think it must inevitably remain so? PG
Nice thought. People/brains ARE stubborn. What do you suppose that means in terms of neurons? What might "believing" be, in terms of neurons? And what is the relation between that and "making observations and drawing conclusions"? Certainly in terms of neurons taking a class is just "making observations", yes? From which one may draw whatever conclusion one likes? Or .... ? PG
And tell us when you do, please? Lots in here, might help to take it apart a bit, focus piece by piece. Yes, an important conclusion is that there is no explanation of all those different behaviors in the individual neurons or the signals they use since, in an important sense, those are all pretty much the same. Which means that an explanation for the large number of different behaviors probably has to be found in groups of neurons rather than in individual ones and, fortunately, the properties are such that one can combine neurons in different ways and get lots of different groups. The "allowed to" is interesting, indeed, and may help understand some things, but not others (not being a "machine"?). So, what kinds of organization might one imagine that would help make sense of that? Just because something is all neurons, does it have to act like a "machine", in the sense that we use that term based on machines we know (and have made ourselves)?, or is it possible that machines we have so far built aren't as elaborate as .... the machines that we are? PG
Signals are conducted about the nervous system in part due to the concentration gradient, and variable membrane permeability that exists at a certain time and place along a particular neuron. The type and quality of such signals, has a great deal to do with their mode of transnmission (chemical or electrical) and the kind of neuron they are travelling within (channel diversity). All of this can be used to explain a great deal. For example, motor neurons transmit via electrical currents because they can travel faster along myelinated axon sheaths than can signals along chemical pathways. Thus, we have a good chance of blocking a punch thrown by the third grade bully. Furthermore, chemical transmission allows for the modification or modulation of the signal such that the receiving neuron is 'flexible' in its response. The chemical intermediary, the neurotransmitter released when the presynaptic electrical signal reaches the presynaptic terminal, can vary. The post-synaptic terminal also varies in that the nature, properties, and number of the proteins embedded in its membrane are any of mnay possibilities. Thus, the range of possible responses to a signal is tremendous. This range of difference in response allows the nervous system to adjust over time, through repeated experience of similar imputs. It has been posited that this is the means by which we learn, and store that which is learned. So, now through practice we can not only avert the impending fist of our nemesis but respond with our own devestating blow.
All of this is wonderful, and indeed begins to explain how our genetic template can begin to be crafted by experience(re: Jeremy's essay) but, of course there has to be a but, what about the big picture? I am with Doug on this one. How are these responses to typical external stimuli stored? Where does the question of choice come into play? What about intuition - that nebulous gut feeling we have that often motivates behavioral choice? What is it about my DNA, thrust into the environmental contexts through which I have lived, that has allowed me to become the 'person' (the brain?) that I am? The questions go on...
I know that we don't have the ultimate answers to these but in a way that is the point. Behavior is a conflagration, a crazy multitude of possibility that evades compartmentalization. I like where we are going but science has never really been great at dealing with the abstract intangibles of life.
I'm inclined to agree with you about science and the "abstract intangibles", but also perhaps inclined to be more optimistic about science's prospects than you. Perhaps, like evolution, its necessary to make easier steps before it becomes possible to make more difficult ones? And the "abstract intangibles", the big picture, is part of the latter? The wherewithal to better understand "conflagrations" and similar complex systems is beginning to come into being, in part because some scientists, like you, recognize existing limitations in understanding, and in part because better understanding the details has brought into existence tools which weren't earlier available. As for the specifics, "memory", "intuition", "choice", "who one is and how one got to be that way" ... we'll at least take a crack at them all. PG
I believe it is important to understand the mechanisms which create neurological activity. It serves as a base to understanding more complex questions. My feeling however is that we may never get around to answering all of the questions which bother me this semester. Even worse is that more questions come up every week.
Even worse? An interesting issue. For a professional scientist, one of the keys to "tasting" a successful line of research is that it "opens up", creating new questions. So I, at least, will take your feeling as suggesting a promising start for the course. So long as the questions are new ones, instead of the same old ones. Yes, we don't want to get into "all purpose excuses" with things originating inside the nervous system. But yes, I think the ones we have will, non-magically, help us with much more than "bodily functions". PG
Appropriately so. Indeed one might wonder if some of one's behavior (a lot of it) is not only not caused by something outside but doesn't follow the "think then act" process either (though we'll have to say more about what that means, and will, in thinking more about the "I-function"). And that really shouldn't bother the Freudian in you. The message there, after all, was that some of one's own behaviors occur without one being aware of their causes (an "I-function" activity?), and that it is helpful (why?) to better understand such causes. So neurobiology is perfectly in line with Freud, no? PG
Even though the I-function can never be damaged, pathways from the I-function box to the myriad of neurons that are responsible for motor control can be damaged as we see in patients with Parkinson's disease. This damage to the brain's telephone wiring that leads from the self to the body's actions doesn't mean that Parkinson's patients are incapable of any desire to execute basic behaviors. They are merely incapable of directing their brain or muscles to do so. Somewhere the action potential gets incorporated by the wrong post-synaptic nerve or just dies out. The importance of observing neural activity is to determine how these messages should have been relayed from the NS to the muscles, and how these pathways can be manipulated so that communication can be restored. Each firing neuron has such a considerable, direct effect on the next neuron in its pathway leading to the intended behavior that the precision with which our unscathed neurons relay action potentials is surprisingly amazing.
Hmmmmm. Lots of assertions, particularly in that first paragraph. Maybe break things up a bit, develop more one at a time? All interesting though. We'll talk more about the I-function and the "self", but don't automatically assume they are the same thing because there are some observations which suggest otherwise. Along a related line, do you really want to assume that all activity is initiated in the I-function box? Maybe some starts outside that box? I like your discussion of connections from the "I-function" box to other places, and problems of interruption of those connections (sort of like the paraplegic, yes?), but why do you presume that the box itself can never be damaged?h PG
Fair enough. But why do you believe these things, what inclines you to be a "biological minded person"? And what do you see as the distinction between biological and psychological? and why is the former needed for the latter? PG
Because the interpretation of a signal is mainly dependent on the specific neurons that are carrying the signal, if the signal deviated from the "normal" pattern of neurons we might actually be able to see thunder. I don't know how plausible this is in real life, so the rest of my comments might be irrelevant. Even if it isn't plausible, it still points to the link between perceptions of reality and behavior.
A lot of behavior that is linked to the I-function is heavily influenced bu reality as it is percieved. If I really believe everyone else is out to get me, then I will act in accordance with my belief. Most other people would then accuse me of exhibiting abnormal behavior because they do not believe that anyone is out to get me. It is abnormal because I am reacting to a view of reality which most people would not share. This can be seen in people who have low self images. If their perception of themselves becomes increasingly positive, there will probably be a corresponding increase in changes of behavior.
But what about views of reality that we expect to be more concrete than self image? What if I covered my ears every time bright light shone in my face, or I closed my eyes every time I heard a loud sound? My eyes and ears would suffer damage due to the fact that they were not protected from the real dangers. I would hope that I would eventually figure out that there was a problem. But it is possible I might not, especially if a lot of other people also suffered from the same problem. We might just believe that our eyes and ears were supposed to fail us early in life. I don't actually believe in a sixth sense, but following along with this line of thinking, you never know.
This brings up the point that a proper understanding of reality is greatly to our advantage. At the same time, however, it points out that we are incapable of discerning what the "real" reality is.
Very well said: there is indeed a quandry there. And you've even given some of the ways of dealing with, by exclusion. Yes, we believe we have a sense of reality because we test it ourselves as well as by comparing it with what other people say. At the same time, people DO see things differently, as we'll talk about more later in the course. PG
Tourette's Syndrome is indeed a very interesting connection from things we talked about (don't worry about the spelling, I had to look it up). And there isn't a general answer to your question, in the sense of one thing that accounts for all examples of things being "allowed" rather than "caused". In general, though, one might guess that there are two broad classes of explanation: membrane permeabilities which lead to spontaneous firing or an absence of inhibition which normally holds spontaneous firing in check. Looking around on the web in one or another situation to see which holds might make an interesting web project. There are some additional subtleties to be aware of, though. Both epilepsy and Tourette's may show some context dependence, i.e. "attacks" more frequent in some sensory environments than in others. Can you fit that into your picture? PG
This concept intrigues me, because it implies that constant levels of neurotransmitters in the brain are needed for normal functioning. Indeed, abnormal levels of dopamine are believed to be involved in both Parkinson's disease and schizophrenia. It seems to me that the amount of a neurotransmitter bound to receptors does not depend on interaction with the environment but instead is relatively constant. Before I was introduced to this concept, I thought neurotrasmitters simply linked neurons together, relaying inputs and outputs from one area of the nervous system to another, constantly changing in response to the environment. Now I see the brain as very constant; even small changes in the amount of neurotransmitter availible are compenstated for by changes in its receptors. When levels of neurotransmitter do change drastically,as in schizophrenia, a individual's whole personality can change, although there is no change in his environment. I am beginning to believe that we are our neurotransmitters; that it is levels of chemicals in our brains, more than any of the experiences of our lives that make us who we are.
p.s Please forgive me if my explanation above is unclear. I found the concept a rather difficult one to explain.
No problem, you've done well, and the issue of internal regulation of both transmitters and transmitter sensitivity is an important and relevant one (though not one we'll spend much time on in THIS course). Who we are is certainly in part a function of transmitter levels and sensitivities, but don't overstate the case. Transmitter levels and sensitivities are to some extent internally regulated but they are also influenced by the environment. And, in the last analysis, its the patterns of activity in neural networks rather than the transmitters themselves (which influence them), which are probably "who we are". PG
While I do feel that the nervous system is an essential part of behavior, I still am not comfortable accepting the statement the brain=behavior. Without an environment in which to exists the nervous system would not be able to function and therefore there could be no behavior, so I still believe that the interplay between external and internal (the nervous system) environments, is the cause of what we call behavior.
I'm content with behavior as a brain/environment interaction, except for one thing which we'll get to as we proceed: it is demonstrably so that the nervous system will continue "doing its own thing" when totally isolated from the environment (for an advance look see Figure 2 of Variability in Brain Function and Behavior). And, of course, the environment has its effects only in so far as it produces action potentials in the nervous system. I agree that for a better understanding of behavior, "it is necessary to understand as many of the variables affecting it as possible". But it seems to me that calling the nervous system simply one of those many variables is seriously underestimating the centrality of the nervous system and its effective identity with behavior. Needless to say, we should touch base on this again and again as the course goes on. PG
Also, I wonder what the evolutionary motivation for hormonal influence on emotional behavior is. This is definitely perceived to be more of an issue for women, who have a relatively well-understood hormonal cycle: everyone has heard about how weepy premenstrual women are supposed to be and what strange cravings pregnant women are supposed to have. Though I believe that these phenomena are often overstated, it has been documented that hormones have a strong effect on emotional state. I guess I wonder first of all what the biological benefit of these emotions is and, secondly, how hormones enhance this. Furthermore, why do we hesitate to examine this relationship in men?
It should certainly be examined more extensively in men and, as we'll talk about later in the course, there is good evidence for internally generated mood variations in all humans, irrespective of sex. We'll talk too a bit about what the advantages of mood variations might be. Interesting and relevant issues. "Evolutionary advantage", though, is a slippery concept, as has been discussed on and off earlier in these exchanges. James Gould, an evolutionary biologist, has written about this slipperiness extensively. PG
Also, I was intrigued by how in some cases the NS does not actively cause a certain behavior but rather actively inhibits itself from allowing that behavior to happen. I did not know until last week that chickens actually do run around when their heads are cut off! I had once seen on a Nature TV show, or maybe it was Discovery, how a female praying mantis will bite off the male's head during mating and how this enhances his "performance". And I had always wondered how that was possible, but I guess the "suppression theory" now offers an explanation.
I hate to sound like the moralist on this forum, but the comments some people have made about attraction and love-- well, they do not exactly disturb me, but they make me wonder. I once read an article about how, despite the protestations of many of us, attractive people do receive much better treatment, not only in terms of romantic involvement but in things such as the kind of service they receive in stores and restaurants. That article said that people seem to link attractiveness to symmetry, and said that the face of Denzel Washington, who most would consider very attractive, is almost perfectly symmetrical.
I guess what actually disturbed me was someone saying how, for example, large breasts are usually a signal that a woman can nurture children very well and this explains why boys are attracted to them, if this is how they are genetically "wired" to behave. Well, maybe this is more the age-old "nature vs. nurture" topic, and I am going off topic slightly. But it seems such information could justify shallow behavior and double standards that I think most people try to overcome through education. After all, if it's genetically determined that men want voluptuous women, or that women want providers with money to take care of their children, why fight it? But it seems that if these genetically-controlled tendecies are followed through on completely, this would mean that many good and decent people would be left out in the cold in the dating game. Or maybe I am being too idealistic here.
Also, assuming that most people try to overcome such animal natures; I know that some studies have shown that the brains of men and women function differently. Well, if some behavior differences (probably not all) between men and women are due to biological factors, would this in itself justify different standards of behavior for men and women? Since I am sure some would argue precisely that, that treating men and women differently is not discriminatory because men and women are different.. On the other hand, this is what some people used to say about white people and black people, and maybe still say -- remember The Bell Curve? I guess the larger question is, should the fact that a behavior is determined by genetic factors be in itself a justification for such behavior?
Also, someone referred to how it was purely evolution that had shaped the development of the NS. But as I learn more and more about the complexity of organisms, especially the NS, I can't help thinking that the mind-boggling complexities I encounter didn't develop purely by chance. I can't help thinking that there was a Designer, a Creator, who somehow guided the process of evolution. And if that is true then the fact that behavior is purely due to the many biochemical processes in the NS doesn't diminish the significance and meaningfulness of behavior.
Lots of interesting issues. To start, you are of course correct that since permeability depends on proteins, genes influence the nervous system (and hence behavior if ...). The operative point is "influence", as opposed to "determine", and I don't think you're being too idealistic: genetic influences should NEVER be confused with "determinants" and used as an excuse for anything. It is indeed the business of education (and culture and parenting and ...) to give people the wherewithal to behave in ways they might not have otherwise (an interesting definition of "animal nature"?). All of which of course bears on any kind of genetic difference, including males/females, blacks/whites, and so forth. Genes don't "determine" behavior, they, among other things "influence" it. There are some more thoughts on the Bell Curve , and other related matters, in Serendip's section on Genes and Behavior. PG
The idea of the combination of inhibition and spontaneous activity was an important concept that I never had heard of and that helped explained some of the underlying causes of behavior patterns.
Glad you liked it. Want to be more specific about behaviors which it might help to understand? Yes, of course, we can't do much with just one or two neurons, but the background on cells will be useful. Any guesses on why, and what the limitations might turn out to be, if any? PG
Granted, on a small scale, things are changed, some become more important, some become less, but the overall effect does not neccessarily change. What types of behavior occur depend entirely upon what occurs in the axons and dendrites and synapses of the individual cells, but knowing that it is just a bunch of ions moving in and out of equilibrium does not change the fact that you swung that bat to hit the ball, or fell in love at that moment, or cried necause someone told you that your grandmother died. Of course, a small change in the way that the ions moved could make you miss the ball, or not fall in love, or just stay shocked, but would that be a failure on the microscopic part, or just a different behavior? And would the behavior chosen vary as to the person, most certainly. If one person is rather poor at baseball, they will miss the ball more often than not, a better player would hit it more often. I do not believe that knowing what happens on every level, changes the outlook on behavior, it only explains some of the mechanics.
Hmmmm. My sense is that there is somewhat more subtlety in your arguments than is fully reflected in your conclusion. You suggest a very interesting way to approach the problem: would changes in cellular and subcellular properties change what is observed at the behavioral level? The answer is sometimes dramatically, sometimes very little. Which is to say, there is not in general a DIRECT relation between lower level and higher level properties, for interesting reasons which it would be worth trying to specify more carefully. On the other hand, SOME things that are mysterious at the higher level can be made more sense of by appealing to "the mechanics". Maybe indeed some of why I was always a poor baseball player has explanations other than "failure to concentrate", "not willing to work hard enough", and the like? That would make me feel a little better about it. PG
C.G. Jung proposes an individual human psyche composed of paired opposites: chiefly, the conscious ego, and the unconscious shadow which, for better or worse, opposes whatever attitude the conscious ego asserts. Jung suggests that each "soul-image" comprises both anima and animus, meaning not that the person is both male and female, but that the soul is at once masculine and feminine.
The sciences echo Jung's suggestion that natural phenomena can be described as both unity and duality at the same time. (Niels Bohr fashioned a coat of arms for himself which bears the motto, "Contraria Sunt Complementa," and which features a Yin-Yang symbol in the center of the crest, alluding to the Eastern philosophies that have embraced this paradox for centuries.) Physics describes light as being simultaneously particle and wave, and shows how it behaves as both. Physicists both distinguish between and concorporate matter and energy, time and space. The idea that paired opposites compose the whole is central to our understanding of the atom. The newest Physics suggests that the oppositely-charged nucleons formerly believed to be fundamental are composed of an even more minute pair of particles, and that both of these particles are, in fact, composed of the same basic material: that the fundamental opposites are actually different vibrations of the same "string." Chemistry provides the imperfect model of resonance structures, which help us to conceive how a molecule can be instantaneously the same and different. Biology tells a story of continual anabolism and catabolism, describing how life is a process of both overcoming entropy and succumbing to it.
In this class we seek to describe the dichotomy/unity of the body and mind. We have agreed that the brain, which gives rise to the mind, is matter which uses energy. We have also agreed that the integrated "signals" that compose the mind are neither matter nor energy. We have voiced arguments that show the mind and brain to be distinct, and arguments which show them to be synonymous. I'd like to suggest that both viewpoints are correct: that rather than trying to decide which one is right, we accept them both, and decide which description is most valid or useful in a given context. I think we need to get comfortable with this paradox; I am impatient to explore it, but I'm not anxious to resolve it.
Interesting, relevant issues/extensions. Let me add an additional extension to mull? The anabolism/catabolism distinction is, of course, an imposition of labels by the human brain on a system which itself makes no, and in some ways has no, such distinction. Molecular resonance, at least in some ways, is a concept developed to update older ways of understanding molecules which no longer proved entirely adequate. The same is, of course, true of the equivalence of matter and energy, and of space and time. All of which is to say that "dualities" themselves may be more a product of the human brain's effort to make sense of things than they are a genuine property of whatever one is trying to make sense of. That, of course, raises an interesting question about the brain: what aspects of its function predispose it to seeing dualities? It also makes it at least possible that "dualities" are simply a common transient phase in the history (past or future) of trying to make sense of things. So maybe brain=mind is the next phase in this particular case? Are there really compelling arguments for keeping them distinct? PG
Regardless of whether it is genetics or experience, I am stunned by how complex attraction really has to be. Think of how many neurons are receiving, processing and transmitting some type of message just to give you that queasy-stomach, rapid heart rate feeling. Each neuron involved is affected by the millions of inputs that have travelled across it in your lifetime. As to genetic determinations, proteins in many of the neurons are going to have to have a certain shape, one out of a myriad of possibilities. And this all has to work in combination. Of all the proteins of all the neurons of all the nervous systems in all the vertebrates with any of all the combinations of experiences in the world-- yours had to be compatible with mine!
Not only compatible with NOW, but, as you say, compatible with a process of generating an increasing match between etc and etc. Yep, pretty extraordinary, when you come right down to the neurobiology of it, which, of course, matches one's experience of it when it happens. Pretty good last word on the subject (though I suspect it won't be). PG
Along the same line, a danger that I observe in the class lectures and discussions is the unstated acceptance of this theory as we continue in our effort to understand the nervous system. It appears to me that we are trying to make the data fit the theory by going ahead and trying to explain things such as the sense of self, love or feelings by the criteria of this theory, that brain is behavior...there isn't anything else. It is obvious that this theory works well on some behavior but leaves a lot of questions unanswered on other behaviors. My assertion would be that this model of Brain=Behavior, although it contains some true elements has been shown by the unanswered questions and issues raised in class to be lacking greatly. So instead of trying to make the observations fit into the model, why not venture to try a new model, a new model that better explains our observations. After all, that's what science is all about, seeing what's wrong with the proposed theories so that better ones can be formulated.
Yes, "thinking about" the brain can be usefully conceived as "a pattern of activity" in the thing which is itself the subject of the "thinking about". What's less clear to me is why you think that itself is a problem. Perhaps its the "objective" vs "subjective" issue? If so, we'll talk more about it after we've looked a bit at sensory systems and perception, since that will substantially blur the distinction between "objectivity" and "subjectivity". For the moment, I at least don't have any trouble with the idea that patterns of activity in the brain can equally well constitute hypotheses about both what is "out there" and about itself. As for "unstated acceptance", I certainly hope that's not what's going on (and don't think it is from much of the forum discussion). Brain=behavior is a model under consideration, and, for what its worth, its a NEW model in the context of human inquiry, one we're examining to see whether perhaps it does a better job of making sense of behavior than older models. The task is not "to make data fit" but instead to look closely and rigorously enough to be able to say with precision if something does not fit and exactly why. Yes, all models ultimately fail. That's the point of science. But its very hard to get to a better one without knowing exactly what is wrong with existing ones. As you say. So where are the unanswered questions, are they truly incompatible with brain=behavior, and why? That's what we're after. PG
Crickets or other creatures with smaller nervous systems don't have as many neurons as humans. Is it possible to program a computer to mimmic or behave as an actual cricket? If each neuron has a certain number of proteins in the membrane of a certain permeability, with an action potential of a certain amount then it seems possible. Except for emergence. We talked about emergence at the first TA session and though we might know all of the rules of "neuronal behaviour", we do not know all, how, or why various unexpected patterns arise. But, it seems as if the prediction of only one pattern would be enough for a pseudo-life form. Also, the signals that spontaneously arise in a neuron can not be accounted for.
PS. I have thought about this for a while. However, I am writing this at 2 in the morning, so please excuse some of the errors.
Don't froget to comment on this or my last one.
Yep, late but done, both of them. And I like you connection to Thomasina in Stoppard's Arcadia. Remember though that it was the slightly younger Thomasina who dreamed of an iterative rule that would account for everything, and a slightly older Thomasina who realized that "heat" precluded that. And one might (indeed we all) suggest that, as you say, its the spontaneously arising action potentials (among other things) which aren't in the equations and constitute the "heat". PG
The two systems I have thought about are language; and the genetic code of DNA. What do they have in common?
1. a set of building blocks: our language uses both the alphabet of 26 letters, and a set of accepted sounds; DNA uses the four nucleotide bases read as non-overlapping triplets to code for the arrangement of 20 amino acids.
2. the reciprocal traits of stability and variable expression. Language is stable in two ways: through time over the course of generations, and in our own memories (for example, words do not change shape or meaning in our memories; they are stored there, ready for use as needed). It varies in the same ways: over time, language slowly changes its shape to adapt to changing environments (old English is different from middle English is different from modern English); and it varies in the way we use it in any given moment (the way we can arrange words is like a mathematical limit approaching infinity). The stability of DNA is in its architecture and in its base-pairing system, and in its mode of reproduction; its variability is in both its differential expression and in its mutability.
There are, I think, more and subtler ways in which DNA and language can be compared to each other. (What I haven't been able to decide is whether DNA is merely analogous to language, or if they can actually be grouped together as modes of information storage and transport.) If we allow for a few minutes the idea that they both might be different ways of doing similar things, then the nervous system is yet another way of doing these things. Would one say that its building blocks are axons, or ions and variable permeability, or transient charges, or neurotransmitters? Or the sum of these things? Are its stability and variability merely a result of its hard-wiring, so to speak? (anatomical specificity and responsiveness to particular stimuli).
One other thing which has influenced my thinking about all of this is a bit of an essay I came across, which described language as "transcending the machine of its own reproduction". What does this mean? It means that the motor neurons which tell our mouths to speak and the auditory neurons which record and translate that speech, as well as books, typewriters, recordings etc, are all parts of the machine of reproduction which convey and store language, but language itself "transcends the machine"; it is more than the sum of its parts. Is the same true of information, then? And doesn't the analogy also suggest that the "self" might also "transcend the machine"? That any system of storing and transporting information might, by virtue of what it does, have a "transcendent" component? Is this what it means to have information be a third component, next to matter and energy, of which the universe is made?
Very interesting, potentially very generative set of thoughts. I trust you'll take it as encouraging (as you should) rather than discouraging that the language/DNA parallel is one that has occurred to others as possibly fruitful to explore. I remember a paper written by a graduate student, Marty Sereno, when I was on the faculty at the University of Chicago. Sereno is currently on the faculty at University of California, San Diego and has on the web a sketch of some of his thoughts. Marty's home page gives the reference to a paper in the Journal of Theoretical Biology in 1991 that you might want to have a look at if you're inclined to think more along these lines.
There certainly are useful parallels in thinking about language and DNA. What intrigues me about both of them is that they are "generative", i.e. the symbols and rules of combination of symbols are such as to allow not a finite but an infinite number of possible combinations. And yes, I think there is an important sense in which language (and DNA) "transcends the machine", at least in the sense that the information contained in any given symbol sequence can be transcribed/translated into other media without changing the information. The same information can be represented, for example, in printed musical notation, in grooves in a record (or, these days, in pits in a CD), and in sound waves. It hadn't occurred to me to speak explicitly of the nervous system itself as an information representation, though that idea is certainly inherent in the way I think about it, and I want to explore that further. Thanks. I'm pleased you like the idea of information as an independently explorable entity. You might enjoy looking at an article I wrote which talks about that idea and what made it occur to me. In return, you want to tell me where the "bit of an essay" is? PGSerendip © by Serendip 1994- - Last Modified: Sunday, 15-Feb-1998 21:46:06 EST