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An ongoing conversation on brain and behavior, associated with Biology 202, spring, 1999, at Bryn Mawr College. Student responses to weekly lecture/discussions. A suggested topic was provided, but students were free to write about any other observations, ideas, or questions that particularly interested them.
A general theme that emerged this week is that the nervous system consists of a lot of different parts which normally function together in a coordinated way, but which can and do, under some circumstances, function more or less independently of one another. If the brain=behavior assertion is valid, this perspective should hold for behavior as well as for the nervous system. Does it? Is it a useful perspective in the context of behavior? Can you think of examples of behavioral phenomena which are more understandable in terms of coordinated elements that are sometimes less well coordinated?
I have seen epileptic fits, and what struck me most was the sense that the person had no control over his or her own body and that they were somehow overloaded and therefore unresponsive to the outside world. Additionally, I wonder what the vision has to do with seizures. Movies and the media, while not the best sources of information, have consistently related flashing lights or colorful display such as video games as a cause of seizures so I am thinking that there must be at least a kernel of truth to it. I am particularly reminded of the movie the Andromeda Strain. One of the characters in the movie has seizures whenever she sees a flashing light. I have heard that a person having a seizure will tense their mouth so much that they will bite off their tongue-could be a myth. A short note here the above information is purely anecdotal so don't take it as truth. Some of it could be a myth.
Given that the trigger for seizures seems to be visual I will contend that seizures are caused by a vivid visual input such as a strobe light. The input causes rapid firing in the visual area of the brain and put the person in the trance-like seizure state. Then the rapid firing spreads to other neurons controlling other parts of the body such as the neurons controlling muscles. This causes the muscles to tense. The tensing of the muscle causes the mouth to clench giving rise to the possibility that one having a seizure could bite off his or her tongue. The tension of the muscles also makes the person unable to stand, and they fall to the floor. Additionally, this rapid firing could spread to other areas of the brain perhaps those controlling hearing which makes the person seem even more disconnected to the outside world. My simple model argues that the epileptic fit starts rapid firing the visual area of the brain in response to a vivid visual stimulus. The rapid firing spreads and affects other areas of the brain causing muscle tension and other symptoms.
If this model were correct, what would it tell about normal function of the brain? It would suggest that the parts of the brain are interconnected. The rapid firing in the visual area does not stay there it spreads. The visual area must be connected to the muscle area. If the areas were not connected, the firing would not spread, and the symptoms would be only be visual impairment. Second, it would suggest that there is a threshold of input that can be accommodated in the brain. That is the brain can be overloaded. Input (such as a strobe light to an epileptic) can be so overpowering that it incapacitates the person. I realize there are broad assumptions based on a shaky model, but I am trying to make the point that understanding disorders can add to what is known about normal function. This seems key to the study of the brain to me. From the book it seems like that it has been important historically as well. Example, Phineas Gage. All in all, the importance of the study of neurological disorders seems twofold-one to learn about the disorder and two to learn about normal function of the nervous system.
Also, I am trying to do some creative thinking about epilepsy because I am considering it as a paper topic. Does anyone have any leads on web sites on epilepsy or seizures?
Some postings at the Epilepsy Web Clinic, at Southern Illinois University, suggest that strobe lights will indeed trigger epilepsy in some individuals, with the data on video terminals being less clear. This looks to me like pretty reliable secondary source information (I found it by using Hotbot to search for a combination of "epilepsy" and "strobe"), though I"d want to look around a bit more, and go to primary sources if I really wanted to be sure.
So your model has a good starting point, for some (susceptible) people. I like your inference that activity probably starts in visual receiving areas and then spreads to other areas (though one probably could have inferred one set of connections, from visual to motor areas, from normal behavior, no?). This is certainly part of the current understandings of epilepsy. The "threshold" of input idea is a good one, but may need to be modified. My impression is that light flashes of particular frequencies are more effective than light flashes of either lower or higher frequencies, so its not a simple intensity or frequency threshold. Any other ideas?
A Hotbot search on the simple term "epilepsy" yielded (today) 43,300 web matches, which is obviously too many to explore completely. You can, though, get some sense of what's out there by looking at some of the first ones on their list, and using interesting links from those to go on to other places ("web-surfing", which one gets better at with practice). On Hotbot, the phrase "neurobiology of epilepsy" (enter it using the quotations or select "the exact phrase" option on the search form) cuts the report down to 19 matches. "Neurophysiology of epilepsy" gets 47 matches. Playing with the search terms (phrases or combinations of individual words (like entering both "epilepsy" and "strobe" (without quotation marks))) is another skill of web-surfing which one increasingly acquires with practice. Enjoy. PG
I was particularly reminded of processes that take place entirely within the body related to pregnancy, birth and lactation. I'll leave the discussion of love/sex for another occasion. Once the process of conception takes place, during gestation, the birth process and post-partum lactation periods various hormones and neurotransmitters affect not only the functioning of the body but are also the cause of certain behaviors.
Oxytocin, prolactin, various prostaglandins and so forth bring about many of the physical changes and processes that are related to successful reproduction from an evolutionary as well as biological point of view. For example the process of birth is started by internal signals. Once the process begins and an incredibly powerful and for the most part involuntary set of physiological events occur. However, even as many of the processes are reflexive in nature, such as uterine contractions, certain psychological behaviors may effect the birth process. This might include fear or anxiety, each with their own sets of neurotransmitters which may interfere, slowing or even stopping for a time the labor process.
And once birth has taken place another complicated set of physiological events occur that are again inter-related to and affect and are effected by behavior. Along with the bodily processes associated with lactation, anatomical and hormonal changes, there are the psychological events that are precipitated by and enhanced by the production of the so called "mothering hormones." Prolactin produces milk for the offspring. But Oxytocin is required for the milk ducts to physically allow the milk to flow. And these two, among other chemical signals predispose and influence the behavior of the mother with regard to her child. Perhaps I'll explore and elaborated in greater detail in a longer piece, however, these chemicals are essential for infant/mother bonding and affect strongly the manner in which the mother relates to the child. Disruption in the production of these chemicals can adversely affect the maternal/child relationship.
The chemicals that the body produces in response to sexual stimulation, pregnancy and lactation in turn have effects on the brain/behavior model. The attachments that are formed in large part by these chemicals within the body make lasting changes in the brain. Couples do continue to love each other when not sexually aroused and mothers and children are deeply attached in terms of behavior long past the pregnancy, birth and lactation relationships.
As a teenager, I was under the impression that parents, especially mothers were a little "nuts," especially with regard to their offspring. Then I had children and learned (experienced first hand) that being a parent does in fact transform one's brain.
Its a common experience for anyone who has children (and a predictable future one for people who haven't.. That's my now fourteen year old son Jed on the left and my now fourteen year old daughter Rachel on the right. Maybe there should be some more research on father/infant interactions (five web matches on Hotbot, see above) as well as on mother/infant interactions (97 web matches on Hotbot)?
Yes, of course, attachment and its understandability in terms of the nervous system is a good subject to think and find out more about. And one that poses some interesting challenges to our general brain=behavior notion, as you point out. Among the things that (one presumes) affect the brain are interactions with others (such as infants) but also hormones and other body activities which originate outside the nervous system. These both influence and are influenced by the nervous sytem (we'll get to this complexity, reciprocal causation, in class in a bit), but are, in our terms "outside of" the box. An interesting question is whether all of their contributions to "behavior" are via the nervous sytem, or whether they in addition contribute to behavior in more direct ways. This bears on an earlier issue raised in the forum: would a brain (nervous system) transplanted into a different body be the same person or a different one? Should we perhaps say body(including nervous sytem)=behavior instead of just brain=behavior?
PG
We discussed that when the leg of a quadraplegic is pinched, there is a reflex without the individual knowing. This suggests that the nervous system may be separate from the self and how people conceptualize the outside world. By an individual being able to express one idea without the ability to feel an outside stimulus also suggest that there is more to the body, like an "I", than the nervous system. This idea of self and how it works is something that should be looked into further.
I very much agree the issue of "self" and how it relates to the nervous system is well worth exploring further. I'm a bit confused, though, about exactly how you think of it at the moment. Why do you think "the nervous system may be separate from the self and how people conceptualize the outside world"? The observations on quadraplegics certainly says that one part of the nervous system can be active without the "self" knowing it, but there's a remaining part of the nervous sytem which could embody "self", no? What exactly do you mean by "an individual being able to express one idea without the ability to feel an outside stimulus"? And how do you get from that to "there is more to the body, like an "I", than the nervous system"? An interesting property of the nervous system which we'll talk more about as we go on, is that it CAN do things "without an outside stimulus". So why do we need something more to the body than the nervous system? PG
With all its complexity, the nervous system seems to portray a degree of organization in the functional connections between its various parts. We know that the dorsal part of the spinal cord is responsible for sensory information transport, while the ventral part carries out motor information. It also fascinated me how much we already know about the various parts of the human brain. The book seems to outline very precisely the functions of various parts of the brain. I was struck by the fact that abstract thought is carried out by specific parts of the brain rather than by their coordinated actions. An example worth mentioning is the one given in the book (pg76) of people who suffered from a stroke and can not identify simple, every day object such as a fork. Yet, during a conversation about dinner table, those same people are able to use the word in proper context.
Very often when reading the textbook I begin to think that we already know much more about the nervous system then we really do, partly because I feel bombarded with all the information for the first time (information that would seem as old news to someone who previously studied it). The experiment that we constructed in class to find out the function of a piece of nervous system got me thinking about various ways that the precise connection between the overwhelming number of the building blocks of the nervous system (neurons) could be established. In Box 3-1 (pg.52) there is a wonderful article on some of the ways that researchers go about determining nerve pathways. When an axon is cut, chemical changes accompany its degeneration. By chemical treatments of the axons and various methods that make them visible, their tracts and cell bodies of origin can be found.
Of course we are no where near unrevealing the exact pathways of signals and the various routes that they can take to finally manifest themselves as a form of behavior. But what if some day every signal and every pathway of the maze can be unlocked. What would this do to our perception of behavior? Certainly it would make the brain = behavior unquestionably valid.
As I am thinking of all this I am starring at the computer screen - an inanimate object. Yet I am sending various signals to it through each stoke on the keyboard and they appear before me as letters on the screen. The computer is wired like the nervous system, on a much simpler level but the metaphor can still loosely be applied. But aside from the complexity there is something else the box is missing....
Descartes famous conclusion: “I think, therefor I am.” came into my mind (brain) as I was pondering of all these possibilities. If some day we could find all of the connections, could we make a thinking machine This would imply that it would have the conception of itself, the concept of the “I”. What would be the implications of this and are we as a society ready for it?
A host of interesting questions, all worth thinking more about. "to think that we already know more about the nervous system than we think we really do" is a good point. Textbooks are (necessarily) "summaries of available observations", even when they don't (for reasons of space) make that clear, and so its worth thinking about everything that is "known" in terms of what the observations would need to be to support whatever is being said. Is "abstract thought", for example, unquestionably " carried out by specific parts of the brain rather than by their coordinated action"? We'll talk more about this as we go on, but its worth noticing that the observations described don't quite say this. Damage to a part of the brain can certainly selectively affect one or another form of abstraction, but does that necessarily mean the abstraction is done there rather than by some form of interaction disturbed by damage to that part?
If one could describe "signal and every pathway of the maze"? Is the brain like a computer? Could one make a "thinking machine"? If the last depended on the first, we wouldn't have to think about it, since there are too many signals and pathways to describe them all in any reasonable time. But maybe all we need for a thinking machine is to understand the general principles? Lots of people suspect this may be just around the corner, so its worth thinking about whether we're "ready for it". Would the "thinking machine" be like current computers? Probably not, for reasons we'll talk more about in class. Anything else on your mind (brain)? PG
1) There is a distinction between the nervous system doing something and being aware of doing something (the I-function)
2) Behavior is an expression of distributed behavior over a large part of the nervous system
3) There must be communication within the nervous system
What struck me most about the discussion was the implication that the person is a part of the brain. There was movement in the foot when it was pinched, but no movement when the quadriplegic was asked to voluntarily move the foot. Since the brain, detached from the spinal cord, cannot move the foot either, it was implied that the person must be contained in the brain. Connecting this to the brain = behavior assertion, I would like to re-examine my original thoughts on this idea.
I think it is more comfortable, at least personally, to believe that the brain is not solely responsible for our behaviors. As I have a religious faith, I still do believe in the idea of a soul but have come to question whether this intangible entity affects behavior. After looking at the complexity of the nervous system in terms of input and output boxes, I think it is possible that the billions of neurons can account for individual differences. In addition, we not only have to consider the immense numbers of neurons present, but also that their innumerable possible combinations would lead to an extraordinary amount of behaviors.
These ideas about the workings of the nervous system and its relation to behavior have fascinated me thus far. I look forward to examining the nervous system in greater detail working from the level of the neuron toward the functioning of the nervous system as a whole.
And so we'll go. But let me make sure I understand where you are at the moment? You're comfortable with some basic principles (clearly outlined), like (or at least accept) the possibility that the self is in the brain, see the potential for accounting for individuality and diverse behaviors, given large numbers of neurons? And so ... you are thinking about the possibility that the soul, while real, doesn't influence behavior? Even though "it is more comfortable ... to believe that the brain is not solely responsible for our behaviors"? That seems to be what you're saying, but I'm not sure. PG
Something that greatly interested me this week was the interaction between different types of neurons (namely sensory and motor) in the body and those that are located in the brain. I find it very interesting not only that there is a great deal of input/output behavior that is solely controlled by the spinal column, but also that loss of function is not always a true loss of function, but rather a perceived loss of function.
In cases of quadriplegics as we spoke of in class on Friday, the ability to function, or in this case to move, is never actually lost. However, because the brain does not receive the signals that a movement occurred or that the leg was touched, it is simply perceived as not happening. This manner of thinking is very different than any in which I have ever thought. I had always thought that when the spinal cord was cut, paralysis occurred not so much because of a loss in information transfer, but rather a complete and total loss of all ability to move and sense due to death of the nerve cells. I didn't know that the body is able to move or perform certain functions without the brain. I always looked at the brain as being the center of the entire nervous system and controlling all function. I think that this is primarily the way that we are taught to think of behavior throughout school as we begin to look at the body. I was taught that nerves sense the external environment and send the information to the brain via the spinal cord. Even in my twelfth grade anatomy class, this was the way we looked at behavior. The brain then decided what to do and sent the message back. I know realize that the process is actually much more involved than that. Not only can the brain control behavior but the spinal column can as well.
The assertion that the spinal column is merely another part of the brain allows for a much greater understanding of the nervous system. It does make things much more complicated, but in order for the brain to control all behaviors, complication is sort of needed. To account for the wide variability in behavior there must be a great deal of different ways that information can be processed and accounted for.
In addition to all of this new information and ideas, I was also intrigued by the fact that the concept of self seems to be located in the brain. Evidently, you can remove the spinal cord and a person will not lose any sense of who they are. However, losing function in other places in the brain almost always accounts for some change in the person's self. I think it would be very interesting to look further into this concept of self, where it is located, and how it can be affected in future classes.
Thanks. You've put very clearly the difference between some commonly held understandings of how the nervous system works, and an improved understanding which better makes sense of observations on quadraplegics (and similar observations in a variety of situations). As you know from our earlier course together, this is, I think, the way science works, by going from one explicitly stated understanding through a new set of observations to an improved understanding, and so thinking about how one understands things at any given time, what it does and does not account for and what is improved in a new understanding, is valuable.
Maybe we can use the same sort of strategy to reach some improved understandings about "self", as you suggest? Certainly the fact that a quadraplegic reports a sense of self is relevant, and one might well want to find out whether a sense of self persists after other kinds of brain damage. At the same time, one needs to be careful about how one interprets such observations. Clearly a sense of self persists in the brain when it is isolated from the spinal cord. But "not lose any sense of who they are"? My guess is that a quadraplegic describes himself (or herself) as different following loss of connections with the spinal cord, so there has been a change, as you were suggesting for other parts of the brain, no? And remember, we don't know whether or not the isolated spinal cord has a sense of self, since we don't know how to ask it. Maybe self, like behavior, isn't one place, but rather lots of interacting places? We'll talk more about this as we discuss some more relevant observations. PG
I missed this, and you're right: conjoined twins of this sort do indeed raise some very interesting questions about distributed control, as they do about a variety of other issues. I too am curious about their early motor development (the story linked above implies they were separated before they could have learned to ride a bike). Were they, for example, really "coordinated" in moving their common legs? Given the skimpy evidence in the news report, what other interpretations are there? What kinds of observations would one like to have made in such a case? Were they perhaps made? PG
The brain=behavior discussion we had the other day made me remember a book I read a couple of years ago. In neurologist Oliver Sack's book An Anthropologist on Mars there is a part called "A Surgeon's Life." It talks about a surgeon with Tourette's Syndrome. This disease is a result of an imbalance of the neurotransmitter dopamine, in the brain. Despite his Tourettic behavior outside his work: his tics, comments, and impulsiveness; inside the O.R. he is a changed man. He doesn't show any sign of Tourette's unless he is interrupted from his work.
In my opinion this is an example of when brain does not equal behavior. The chemicals in his brain are telling him to act out his Tourette's but his surroundings have a calming effect on him. I wonder why this is, is there any medical explanation for such behavior contrary? Is it that the situation is overcoming the chemicals in the brain? Could certain situations for people with other neurobiological disorders have a comparable effect?
I too think the observations in "A Surgeon's Life" are fascinating, but am less sure they violate the brain=behavior idea. The "surroundings" are, presumably (and as we'll talk about more in a couple of weeks), patterns of activity in sensory neurons. What the brain does at any given time is a function of "chemicals in the brain" together with the patterns of activity in sensory neurons, so its not clear to me that the fact that "surroundings have a calming effect" says that behavior is not what the brain is doing. In fact, "chemicals" probably ought to be thought of not as "telling him to act out his Tourette's", but rather as "influencing how neurons fire", with particular patterns appearing as Tourette's symptoms and others not. Does that help at all in making sense of the whole thing? We'll talk more about "chemicals" (neurotransmitters, neuromodulators, neurohormones, hormones) and their role in nervous system/behavior as we go along. PG
Yep, that's the point exactly, and nicely illustrated (let's get rid of the terms "reflexes" though, for the reasons discussed in class). Dissociation of function doesn't depend on dramatic nervous system damage but is instead a fairly common phenomenon in normal behavior, once you start looking for it. We'll talk more about piano playing, and related things, as we go along. PG
The issues addressed last class period posed a very interesting question for me. Does the individual need a body? It seems like a strange question to ask, but the quadriplegic paradigm brought up in class the other day suggests that this might in fact be a valid inquiry. From what I could gather from class discussion, the quadriplegic has no control of any bodily functions occurring below the waist. When asked to voluntarily move a limb, the quadriplegic fails miserably at the task. Conversely, any sensation retrieved bellow the neck does not register in the brain-i.e. the sensation is not validated. As such, the only movements which the quadriplegic can make are those which are involuntary. Even in executing involuntary movements, the quadriplegic is actually unaware of having performed any such task. In this case, the body has a 'mind of its own', so to speak. If this is the true, then the body is not really necessary for the 'personality' to thrive. In a way, the quadriplegic lives in his or her mind, not in his or her body.
It could be suggested that this particular paradigm strengthens the brain=behavior argument in the sense that the only thing which seems intact in the case of a quadriplegic is the brain. If behavior is thought to encompass all of the things which make each individual unique (personality, etc) then it makes sense that an intact brain=intact behavior (in this case I refer to non-superficial, i.e. non motor-behavior) as observed in the quadriplegic. But this seems like a very simple conclusion to make. When I think of the ramifications of certain degenerative diseases (Parkinson's, Alzheimer's) I think of a brain which (in the final stages of illness) is no longer 'intact'. It would seem that with those afflicted with such diseases, the person or individual would cease to exist since the brain looses its ability to function. In this case, 'behavior' would also cease. Does this mean that there is no longer a person in a brain/body in which the brain degenerates? If the brain only functions just enough to promote the bare necessities of colloquial life (respiration, vascular activity etc), what have happened to the other behavioral attributes which are considered to be equivalent to the brain and its function? When I see or think of someone who has been afflicted by these 'brain melting' diseases, I always assume that their 'self', 'personality', soul, etc. is still in them somewhere. Just some question. Sorry for the randomness…
Randomness is not always a bad thing. And this isn't so random. But let's be a little careful about the terms we use. "Personality" may be a little much, given the observations we have so far on quadraplegics; we'll talk later about what one does or doesn't need in the way of the nervous system (and other things) to have "personality". And remember that the quadraplegic has a body (part of which can be neither controlled nor sensed, and part of which, the head, can be both controlled and sensed), so its a little extreme to say that the quadriplegic "lives in his or her mind, not in his or her body" (though we'll talk later in the course about a sense in which this is almost certainly true for everyone).
That leaves, though, an important point which you raise nicely: if a sense of self persists in the absence of communication from the spinal cord, does the converse hold? Does damage to the brain lead to loss of a "sense of self", even if the spinal cord (and the rest of the body) is intact? And Alzheimer's is certainly a relevant consideration in this regard (if one presumes a relatively intact spinal cord in this syndrome). You "assume that their 'self' ... is still in them somewhere. From her experience with such patients, Sarah suspects differently. You two want to compare notes? How would one decide? Its obviously a question of both intellectual and quite practical importance. PG
One area of behavior that was brought up in class is experience, information that one is able to perceive and store as memory in the brain. When we look into this idea of memory, we're not just looking at one individual neuron that stores the information, but a team of neurons that are working together. My question is - if all these neurons are working together, how is it that memory can be lost or unretrievable if these neurons share information and are connected to each other? Also, with many neurons functioning to store information, is there really a limit as to how much information that a person can accumulate? (I'm just thinking ahead...I know that we haven't yet reached the topics concerning learning and memory in class.)
Thinking ahead is fine. You can even read/explore ahead if you like, and come back and tell us how you think it relates to what we're currently doing. Conversely, you can try and figure out how what the implications of what we're currently doing might be for something yet to come. As you've sort of done here. I think it will be easier after we know a bit more about neurons, but can you imagine where information resulting from experience might be? and hence how it might be lost? And how it might be represented, and hence worth there is a limit to the total amount of information stored? PG
Neuropsychological study attempts to draw conclusions about the functional structure and organization of the brain from observations of impaired behavior. Such research depends on the identification of brain damaged patients who’s behavior demonstrates some sort of cognitive behavioral deficit. It is thought that there are modules in the brain which correspond to various cognitive functions and behaviors, and that a specific functional impairment corresponds to a specific impairment in the brain. In this way, the study of brain damaged patients allows for observations to be made about the specific relationship between brain functions and cognitive functions, and thus between brain functions and behavior. For example, the study of patients with various types of acquired dyslexias (reading impairments which result from brain damage later in life) can provide important information about the normal reading process.
It seems that brain damaged patients represent circumstances in which certain parts of the brain are impaired or cut off from others, making normal coordinated activity impossible. In these circumstances, patients often show very specific functional behavioral deficits. So it seems that the idea that the nervous system consists of a lot of different parts which normally function together in a coordinated way, but which can and do, under some circumstances, function more or less independently of one another is a useful perspective in the context of behavior.
Yes, indeed, neuropsychology tends to characterize behavior in terms of interacting "cognitive functions", which can be disturbed somewhat independently of one another. A similar idea underlay "phrenology", the effort to describe behavior from bumps on the head which has (appropriately) fallen out of favor. An interesting question is whether the general approach, as in neuropsychology or in what we do in class, is sensible and appropriate. Are there other ways in which the nervous system, or behavior, might be organized that we are missing because we presume organization in terms of interconnected boxes (sometimes called "modules") each corresponding to an identifiable behavioral or cognitive unit? How does one know what the relevant units are? Karl Lashley's "equipotentiality" and "mass action" principles were one effort to point to an alternative form of organization. More recent interest in "neural networks", "distributed processing" and "connectionism" is another. So the issue is by no means a settled one, and would be worth spending some time reading and thinking about if one were so inclined. PG
By "brain" in "brain=behavior" I thought we understood "nervous system". So yes, I agree with you that it is the entire nervous system we must be talking about. So, the quadraplegic adds the additional interesting thought that one needs the brain for "voluntary" behavior? That's something we'll want to explore further: what exactly does one mean by "voluntary"? That which "can be controlled"? By whom or what? And what does that mean in terms of neurons? PG
The quadriplegic from our discussion had the ability to think, speak, see etc., since the parts of the nervous system that enable these processes to continue are above the break in his neck. But what if he thinks that he isn’t truly living without the ability to command his own movement, much less ride his Harley? If he is considered “alive,” but severely disabled, what is the verdict for the other possible losses of function due to neurological trauma? It is true that the person is in the brain, and that the entire nervous system doesn’t have to be functioning properly for a person to still “be.” In the case of our paraplegic, this seems clear. What if someone has autonomic function but is continually unconscious? No autonomic functions either? What exactly is the definition of brain death? What is the role of life support systems? If your heart is still beating are you alive?
I realize that this is bringing up issues for which there is no clear answer, that technology has grown so fast that our legal and personal definitions of life and death have to catch up. I do know that the legal definition of death has changed a lot in the past 30 years, though I doubt that it is yet adequate. What do the words “life” and “death” mean when we have technology that can perform functions for our nervous systems when they quit on us? It seems that a machine can’t take the place of a self. For someone who defines self as being capable of moving his foot if he wants to, even partial trauma to the nervous system could be too much. There is something disconcerting in the idea that consciousness, or self, can still be there, but that it can lose the ability to control the body it resides in. The breadth of function the nervous system has in the body is astounding; it seems to be truly the bottom line for the function of all other physiological systems, and the genesis of definitions for “life” and “death.”
I very much agree that the quadriplegic illustrates some general principles of nervous system organization which, properly understood, do indeed require some significant rethinking of not only "self", but also "life". If one were interested, one starting place for looking into this sort of matter might be Brain Injury and Brain Death Resources, provided by the International Network for the Definition of Death. Be sure and let me know if you turn up other interesting things? PG
From your response to my comment last week, you told me of a study about a damage to the brain causing a change in behavior. One of the implications of the comments I made was that values and self would be unaltered by damages to the brain because of the distinction I made between behavior, brain, and self.
In a study done with autistic children, it was found that: "With respect to brain structure,...[an examination of post-mortem brains of several individuals identified] two areas in the limbic system which are underdeveloped--the amygdala and the hippocampus. These two areas are responsible for emotions, aggression, sensory input, and learning." from autistic.org
I take that this underdevelopment can be considered as a form of damage to the brain. If it is so then we expect autistic children to have a change of behavior. And in fact this is what we observe. They are usually slower in learning (except when they're a genius at something) than the average kid in school and they seem to not understand reason when spoken to. As you put it in your comment, I gather that this change in behavior due to this damage is permanent and this changes self.
In another recent study done on 20/20 (not medically proven) they found that many autistic children behaved normally when they were spoken to with a tune. One mother who's a school teacher found that her autistic child could understand what she was trying to instruct him to do when she sung the directions instead of just telling him. He would also listen to reason when the mother explained it to him by singing what she wanted to say. Several mothers of autistic children tried this new approach and many found it to work and they were able to communicate with their autistic children.
Does this mean that the change in behavior associated with the damage to the brain is not permanent and there are ways to getting around it? That what happens to the brain physically, may add a different response to inputs but the original (norm) response is still somewhere in there and just needs to be found? Or am I just taking these things just a bit too far?
No, I think you're exploring exactly the right sorts of questions/thoughts. Not so dissimilar from those of Jess, Feyza, and Sarah, whose thoughts (and my responses to them) you might want to look at if you haven't already (see Mahalia for some additional thoughts). Yes, I think there's lots of evidence that changes in at least some areas of the nervous system are associated with changes in "values" and "self". Autism may well provide an example (though there is still some uncertainty about the reliability of known brain correlates). Alzheimer's (see Sarah's comments) and Phineas Gage (mentioned by several people) are also relevant, and it might be interesting to see what else we could add to the list. At the same time, brain damage does not make certain behaviors inevitable, any more than behaviors are inevitable in an undamaged brain (remember the Harvard Law of Animal Behavior?). The point is similar to the one I made in response to Feyza's comment: behavior is not solely a reflection of the structure of the brain but an interaction between that and other things, including input signals. So one might indeed find ways to interact with autistics which would alter their behavior. Does that make sense? PG
When we posed the question of brain=behavior, I believe the entire nervous system is included in "brain." The nervous system, as a whole, is made up of neurons which produce behavior. To a minimal extent, the spinal cord and brain can act alone- for example when we observe reflex actions in a quadriplegic person.
Lacey presents an interesting question of the defination of life and death: can life exist solely within the spinal cord. When is a person considered brain-dead? Certainly an interesting topic for discussion!
And maybe for a little looking around to find out exactly what the criteria for "death" are in various places (both in our culture and in others), and to try and figure out why these various criteria have been adopted. You and/or Lacey want to take a crack at it (see my response to Lacey). PG
What still surprises me is that the interaction of these cells makes thought and behavior, that whatever chemical or electrical interactions passing between these smallest "boxes" of the brain, overall accounts for ideas and everything in our brains. There have to be different signals that pass between the same neurons, for instance to tell a sensory neuron in the hand that something is hot rather than cold. I want to know how neurons sending signals leads to the larger "boxes" sending and receiving signals, eventually translating into something bigger than a simple electrical or chemical impulse. I can see how muscle coordination could be accounted for by a simple relay of electrical and chemical stimuli, but I can't see how thought can be defined by the same mechanism.
Fair enough. Let's finish up the neurons and how they communicate with one another and then get on to "muscle coordination". That will turn out to be a less simple problem than you might imagine, and maybe to give us some hints about what "thought" could be. PG
Well, then alittle later on the text started discussing how not all neurons are necessarily alike in their strength of signaling or in the types and numbers of ions they use to accomplish it. This struck me as a more plausible (and possible) explanation for differences in signals, inputs and outputs.
I suppose now I am interested in finding out more about the type of signals that are used between neurons and those used to generate inputs and outputs. How do chemicals in the body or inputs from the outside world trigger responses in the nervous system? I am interested in seeing how these similar "little boxes" achieve so much diversity, and how electrical signals make me laugh, think, smile....whatever! Understanding the complexity of the nervous system, it seems, lies in our ability or inability to understand how these signals work. How are they routed, stored and processed? We can see the physical structure of the system, but signals, atleast to me, seem intangible- atleast for now.
You and Marion (above) seem to be in about the same (appropriate) place. Yes, there are differences among neurons at some levels of analysis, but they are also, as you say, surprisingly similar at other levels of analysis. "Different arrangements" of quite similar things ARE an important part of where diversity comes from, as we've already begun talking about ("anatomical specificity") and will continue discussing (see my reply to Patricia for a bit more on this theme). PG
In the case of patients with mental illnesses ,there is not generally a problem with the portions of the brain devoted to maintining homeostasis, sense perception, or hormone regulation. Schizophrenia seems to be a what occurs when the neocortex fails to coordinate speech centers with memory centers, and those with conscious processing along the lines of the "I-function." It is because mental illnesses do not generally affect aspects of behavior which are just as under the control of the CNS as the "higher" ones that they are called "mental," not physical illnesses. So here we see a case of different elements of the nervous system operating independently.
Yep, one can have and maintain conflicting thoughts/emotions/ideas. And certainly various forms of psychopathology appear as disturbances in some aspects of behavior, while other aspects are more or less intact. An interesting question is whether those "dissociations" correspond to activity in different nervous system "boxes" or whether there is some other way to account for them (see my response to Lauren).
Looks like something got cut off at the end, huh? I can add it if you know what it was and want me to. As it is, you've well summarized a number of important points we've touched on. Be a little careful though about "brain", "nervous system" and "body". The confusion is partly my fault, for saying "brain=behavior". In that shorthand, I mean by "brain" the entire nervous system. So the quadraplegic doesn't show "how the body (as distinct from the nervous sytem) may be able to function without the help of the brain". The body does what it does because it has in it a piece of the nervous system (the spinal cord). What is important for understanding behavior is, as you say, the communication among the various parts of the nervous system (including the spinal cord), as well as communication with various parts of the body (the rest of it, excluding the nervous system) and the outside world. PG
I have a question. How can we keep saying that it would be good to find out the exact significance of each neuron in the body, to find its exact function. How can we say that is even possible? Isn't the functioning of the nervous system, our behavior, our thoughts, etc... inherently different in each person due to the fact that not everyone's neurons functions in the exact same way? Every behavior is due to a complex network of interconnected neurons firing and receiving signals from each other? Aren't we eliminating the possibility for individual differences if we say that we should find the exact function of each neuron? Granted, if it were possible to figure out the purpose of every single neuron in the body, that would be very interesting-- but it seems to me that it is impossible due to the sheer magnitude of neurons and also due to the fact that every neuron is not the same among every person.
I am also very intrigued by the ideas that have come up concerning life vs. death of the brain, of the Self. If anyone has taken a physics (or chemistry) class before, they have heard of the concept that energy can neither be created nor destroyed, just continue on in another form. If this is the case, then how can we say that we ever die?? If our body and our brain is made up of a form of energy (electrons, neutrons, protons) which make up atoms, which make up molecules, which make up cells, which make up the body, how can we say that we actually die? If we claim that brain= behavior, therefore our thoughts come only from our brain, then shouldn’t we assume that our thoughts are a type of energy? Does the energy of thought have substance? If it is true that there can be no annihilation of something that exists, then what happens to thoughts, to the presence of a being, to that wonderful flow of energy that we call feelings and awareness if the energy is no longer operating in the form or with the same structure as in the past?
In other words, perhaps I believe even more strongly in my assertion that there is more than just what we call the "brain". Perhaps brain does equal behavior, but keeping in mind the fact that energy can never be destroyed, we have proven that some sort of energy (a soul, perhaps?) exists and cannot ever be destroyed, no matter if the neurons of the brain stop firing or the heart stops beating. The brain does equal behavior, but there is also something else in that equation, an energy, a soul.
Interesting set of thoughts. Let's start with the question. You and Nicki both raise essentially the same related issues: are neurons different from one another? is that what makes people different from one another? Yes, neurons are different from one another at a sufficiently fine level of analysis, both within and across organisms. At a grosser level, however, they are strikingly similar. The interesting problem is which level of analysis is relevant for understanding differences in behavior, something we observe at a still grosser level of analysis? Most people are inclined to look for explanations of differences at a higher level of organization in terms of corresponding differences in the "building blocks", so would expect that it is the differences in neurons which yield differences in behaviors. It is in principle equally possible, though, that the important difference is not in the building blocks but rather in how they are put together. That's an important idea to keep in mind for the nervous system (and generally): differences might exist even if the building blocks were identical (different atomic elements are made of identical building blocks, protons/neutrons/electrons, but have different properties because they are arranged differently; different organisms are made of the same atomic elements, but have different properties because they are arranged differently).
This perspective can be brought to bear on the life/death/thoughts issue as well. One possibility is, as you say, "that wonderful flow of energy that we call feelings and awareness" is a persistant thing in its own right, which is added to assemblies of atoms (or neurons) to give a living, thinking person. An alternate possibility is that it is instead a property of atoms (or neurons) arranged in particular ways. In either case, the wonderfulness of the feeling (a property at a higher level of organization) would be there. So how could one distinguish between the two forms of explanation?
I'm on your side, for most issues. Mental illness is not an indication of "badness"; those having such problems should be sympathized with and helped rather than shunned (its perhaps worth thinking a bit about why mental illness has, historically, been treated differently from other forms of illness). And medication is demonstrably not an adequate intervention in all cases. And what is needed is a combination of medication and psychotherapy. As I said in response to your last posting though, I think emerging understandings of how the brain works will support your intuitions, rather than being antagonistic to them. There is more to the brain than the kinds of functions that can be altered by taking medication, as we'll talk about extensively. PG
(1) the brain (nervous system) is independently functioning
(2) brain=behavior
(3) behavior is independently functioning
It seems that this theory that the brain and behavior are compartmentalized but that the compartments act cooperatively has temporal as well as physical implications. Not only are we capable of engaging in innumerable, unique behaviors- even more amazing is the fact that we can perform many of them concurrently. For example, right now I am breathing, blinking, typing, thinking of the words to compose next, and reviewing those I've composed so far. That I can perform so many of these (and other) tasks simultaneously implies that many, specific neurons and neural centers are being utilized simultaneously. If brain=behavior, and if the neurons controlling my current behaviors are both compartmentalized (to permit the performance of more than one task) and interconnected (to allow these tasks to occur together temporally) than perhaps behavior can be thought of the same way.
If this is true, every distinct behavior can be seen as the outward manifestation of a task-specialized neural network; these task-specialized neural networks can be seen as being simultaneously activated to allow for separate behaviors to occur together in time. By "tasks" I don't mean typing, eating, or walking as much as I mean identifying inputs, determining and relaying the intensity of inputs, integrating inputs, and initiating outputs; it seems that these are the primary activities or tasks of the nervous system. When these tasks yield an output that we call "behavior" then the behaviors we exhibit must be seen as being just as compartmentalized and coordinated as the neural networks and processing that produced them. It is as if everything we do and everything we are can be reduced down to layer upon layer of unending stream-of-consciousness-like neural processing. Stream- of-consciousness-like because behaviors seem to be so seemless although they are distinct and unending because our neurons just keep firing away...until we die.
Its a nice set of images, and probably accurate for many aspects of brain/behavior. One is indeed normally doing many different things simultaneously, and this corresponds to on-going activity in lots of different neuronal networks. On the other hand, there are also, at the behavioral level, the phenomena of not being able to rub your stomach and pat your head simultaneously, of being distracted from thinking about one thing when something else comes up, and so forth. Want to try and imagine how one might account for that sort of thing in terms of neurons?
After our discussion about the paraplegic I began to think about the concept of self that is held by human. When the paraplegic, or their is told that he or she will never walk again, this fact does not alter their "self." They are now living with the condition of paraplegia, but what defines a humanÕs concept of I, the ability to think, relate to other human and situations. Even if their personality changes as a result of their physical defect, we would not consider this a change in their self, just their emotional state. In most cases our sense of self is not connected to our physical self, but rather our mental. Under the assumption that the brain, or the nervous system, equals behavior, and the fact that the concept of self is entirely attached to the functions of the brain, than people who acquire a neurological disorder during their lifetime no longer have the same self, are no longer the same people. Yet in many cases the brain can change only to affect very small portions of a personÕs behavior. For example many stroke only affect parts of the brain that control very distinctive aspects of behavior such as moving a thumb, or the ability to see out of one eye. We may not say that these are not the same people, but what about in the case of the deterioration of the function of the whole body, including facial expressions, where the cognitive functions can not be expressed to the outside world. The paraplegic may not be able to control the movement of his body but he can still communicate his emotions, dreams, need to the world around him. His persona is still perceived by other humans as being his own. Yet when a person is not able to present their inner behaviors and thoughts to the being around them than they are not perceived as the same personality.
You're thinking appropriately about a range of issues similar to those raised by several of your colleagues (see my response to Ellen). With an interesting addition that is worth highlighting. You talk not so much about what a person themself thinks/feels about themself following nervous system damage, but rather how they are perceived by others. That's an important distinction, which we'll want to keep in mind as we talk more about what the brain is doing and how. There is what is observed by others and what is felt internally, and the two may or may not be the same. PG
This story is important to me because I am still struggling with the idea of brain equaling behavior and what the mind really is. I still believe that there is something else there. I find the whole concept of neuron triggoring responses very interesting and explanatory, but some of the things that we as humans are capable of doing, I have a hard time explaining using only neurons and their communication. For example, how do people who see a loved one stuck under a car find the strength to lift the car off of the person? That doesn't seem like something that is possible purely through the output of neurons to muscles. If it were, why wouldn't we be able to do it all the time? And where do certain types of instinct come from? Are they all caused by interactions between neurons? I'm going to keep thinking on these issues:)
That's the best thing to do: keep thinking ... and making new observations. The notion of disembodied selves is a common one in literature, with a recent explosion of stuff associated with the idea that maybe a self could be put into a computer (one of my current favorites is a science fiction novel, Deus X, by Norman Spinrad). Would it necessarily be a state of no fear, implying that fear always stems from the body? And that raises a more general question, which we'll want to explore further. What parts of one's experience of oneself come from "outside"? and what parts from "inside"? Are those two distinguishable in any meaningful sense? And if they are, would an "inside" exist in the absence of an "outside"? Some of these are, as we'll see, approachable questions when phrased in terms of the nervous system, i.e. one can say a bit about what a disembodied brain might do. We'll see whether that does or does not speak to the question of whether a disembodied (including brain) self could exist. PG
When we did the nervous system box diagram, it immediately reminded me of the way computers sometimes process information. I've written in a few computer languages, and many different methods are used to process information. If I remember correctly the tree sorting method or the array sorting method is similar to our conceptual idea of the nervous system where there are boxes within boxes, and each box has several different options. This just indicates that computers in the future WILL have the capacity for very complex behavior.
I don't know about you, but I seem to encounter "glitches" all the time (and do not, to my knowledge, have neurological damage). And they can sometimes be pretty suggestive of underlying brain/behavior functioning (see, for example, the article on Slips of the Tongue in the Scientific American list at the end of the course syllabus). They also sometimes give me new insights into things. The wonder of life? Computers as a metaphor for the brain (and vice versa) is a very rich set of issues, well worth thinking more about. And one we'll talk more about in class, so your experiences will be helpful. PG
What about the nerve response in a paraplegic? The sensory neuron picks up on a stimulus and the motor neuron jerks the leg, yet the brain is cut off from those nerves. Is that considered a behavior, if not what would one call it? The brain never realizes that the leg was pinched and the person cannot voluntairly move its leg. Brain=behavior?
In response to Patricia Kinser's discussion of the soul...this is the basic idea that I was posing last week when I spoke about the doctor that I knew that said that a difference came over a room when someone passed away, that a sort of coldness came through. Would this be the energy leaving the body in search of another physical host? If this energy is within the soul, then does the soul control the brain which in turn dictates behavior? Hmmmm...
Hmmmm, indeed. See my response to Patricia?? We've got the alternatives clear, so let's (as several people have suggested) focus for a while on the nervous system, what it can do and how, and then come back to ... whatever else there might be? Agreeing that "emotions and desires", and any other things one experiences, ought to be counted, for our purposes, as "behavior". OK? PG
After taking a mixture of mind-altering drugs one night, Stephen D., a 22-year-old medical student, dreamed that he had become a dog and was surrounded by extraordinarily rich, meaningful smells. The dream seemed to continue after he woke up‹his world was suddenly filled with pungent odors. Walking into the hospital clinic that morning, "I sniffed like a dog. And in that sniff I recognized, before seeing them, the twenty patients who were there," he later told neurologist Oliver Sacks. "Each had his own smell-face," he said, "far more vivid and evocative than any sight-face." He also recognized local streets and shops by their smell. Some smells gave him pleasure and others disgusted him, but all were so compelling that he could hardly think about anything else. The strange symptoms disappeared after a few weeks. Stephen D. was greatly relieved to be normal again, but he felt "a tremendous loss, too," Sacks reported in his book "The Man Who Mistook His Wife for a Hat and Other Clinical Tales". Years later, as a successful physician, Stephen D. still remembered "that smell-world‹so vivid, so real! It was like a visit to another world, a world of pure perception, rich, alive, self-sufficient, and full...I see now what we give up in being civilized and human."
This story is amazing, almost hard to believe. But we all can relate to it in some way. Our sense of smell, while not as powerful as that of other animals, is still quite capable--scientists believe that most people can recognize 10000 different odors. We have all shared the experience of having a smell conjure up a vivid feeling or memory from our past. We are exposed to an odor that we have not experienced since our childhood, and suddenly, we have a full sensation of the being at summer camp, our grandparent's house, or nursery school. That these memories are conjured automatically, with out conscious effort, must somehow be a function of the direct connection of the olfactory nerve to the forebrain. This is a rich topic. Some current research on the sense of smell envolves identifying the specific receptor proteins that recognize a given smell. Smell is a unique sense, because it actually involves a chemical sampling of our environment. Unlike with taste, which can pick up 4 types of stimuli, our smelling device can somehow recognize the distinct shape of thousands of different chemical puzzle pieces.
Smell is indeed an interesting, oftimes neglected, sense. One of the major centers for research on it is, though, in Philadelphia: the Monell Chemical Senses Center, and there is some interesting work on the central processing of odor inputs which may turn out to be important for better understanding sensory processing in general (see the article on The Physiology of Perception on the Scientific American list at the end of the course syllabus). What's less clear is whether it is significant that the olfactory nerve is the forebrain's only sensory input nerve. This may be an evolutionary vestige, rather than a feature of significance for information processing in existing brains. The nerve terminates in evolutionarily older parts of the forebrain, rather than in the newer neocortical regions. On the other hand, people do report particularly acute memories related to olfactory input, so it might be worth comparing and contrasting the projections of the olfactory system with those of some other sensory system to see whether there are differences which might correlate with such observations. What is it you find hard to believe? That drugs can alter brain function? Or that one might be capable of more intense olfactory experiences than one normally has? Both? Can you imagine ways this might happen in assemblies of neurons? PG
Like several other students have already noted, the example of the quadriplegic discussed on Thursday was very interesting. I was surprised that although the spinal cord in the quadriplegic was severed, the body can still have reflexes in the areas where there are no longer voluntary movements.
If both voluntary and involuntary motions are included in the broad description of what makes behavior, the implication of this is that the entire nervous system, and not only the brain, equals behavior. So perhaps nervous system = behavior
Speaking of severed spinal cords, I read/saw on television a while ago that scientists have successfully "reversed" paralysis due to a severed spinal cord in mice. In the experiment, the spinal cords of mice were severed, making them quadriplegic. Then the scientists used bundles of nerves to reattach the spinal cord at the cut. The mice regained control of their legs.
If such results could be produced in other animals, it would prove to be one of the greatest breakthroughs in medical science.
Yep, entire nervous system.
Efforts to promote central nervous system regeneration in mammals have indeed been increasingly successful in recent years. There's a set of linked pages with a lot of information on this for the layman here. At the same time, things are not yet very close to a state where its likely to be helpful for humans, as the linked material notes and a closer look at the actual observations and their complexities would make clear.PG
This past summer I volunteered in the dementia ward of the special care unit of The Quadrangle, a local retirement and assisted living community. In fact many of the patients/residents there were once professors (or are the children of one time professors) from Haverford and Bryn Mawr. These individuals for the most part were extremely well educated and widely traveled. Their behavior (their brains) had been uniquely shaped by the lives they had experienced and the world they had explored. This however was not evidenced in their behavior. Sadly, on the locked ward it becomes difficult to imagine that these 'individuals' have a unique personal identity at all. The loss is epitomized by the stories told by visiting loved ones who go unrecognized. As well as the staff members who watch individuals progress all too rapidly from stage I to stage III, left only to share stories of whom these bodies once were.
Perhaps it seems easy to dismiss this as my own inadequacy at observing the finer qualities that make these patients who they are, regardless of the loss of memory, the confusion, and the frustration they inevitably experience. But in fact, when visiting home over winter break I again witnessed the same loss of self that results from this degeneration of brain coordination - in my grandmother, stage III. In the three weeks I spent at home she went from recognizing my grandfather as her husband of more than 50 years, to staring at him with the blank, vacant glare typical of so many AD patients. My mother said that 'the saddest thing about this disease is not only that you lose who you are - but that you become like everyone else - simply the symptoms of a disease'. I find this description quite true, my grandmother who I knew and loved, is gone. Her body is still alive, but the part of the brain, her behavior, which was what we may define as 'self' no longer lives.
The way in which this disease manifests itself lends further credence to the brain=behavior proposition. As well as provides rather compelling evidence that the 'self' or 'I' that we have been searching for also resides within the brain, or at least in some portion of it. The fact that this self can be lost, can quite literally die, and yet the body go on stands in interesting juxtaposition to the quadriplegic, or Parkinson's sufferer whose body is beyond their control and no longer their own, while that 'I' or 'self' remains in tack.
***If you are interested in volunteering at The Quadrangle or at some other service opportunity please feel free to e-mail me, or stop by the CSO.
Many thanks for sharing your experiences, which bear on a number of the comments made by others (see my response to Ellen). My experience (with my father) mirrors yours: dementia certainly seems to someone outside to involve a substantial loss of "self". There remains, though, the difficult question of whether there is a "self" there which is simply unable to express itself in observable behavior. PG
"Bill" is a friend of mine who has consciously experienced travel to other planets and other solar systems. Bill has also experienced personal conversations with angels and other spiritual entities. The people who know Bill do not believe that Bill has done these things. Bill is aware of the opinion of those around him that his experiences are not "real," but Bill will tell you that he has indeed lived through them. I think Bill’s experiences are indeed "real," but may not reflect the existence of corresponding external inputs. Schizophrenics are understood to be unusually sensitive, so perhaps Bill is experiencing the "altered yet more perceptive view of the world" that Ms. Kinser mentioned last week. Or, perhaps the sensory input Bill believes he is receiving originates within his nervous system rather than actually being brought in from the external environment. Bill’s consciousness perceives the existence of a "sound" (such as the voice of an angel with whom he believes himself to be acquainted) originating in the external environment. But, if Bill’s friends and doctors are correct in that there is no such sound, the sensory neurons in Bill’s ears ought to be telling him no such sound exists. This seems to be a lack of communication between two parts of Bill’s nervous system: his consciousness and his auditory sensory neurons.
What is responsible to the uncoordinated behavior of the nervous system in these cases? If a quadriplegic’s failure to consciously perceive external inputs can be explained by the lack of something, perhaps the schizophrenic’s perception of external inputs which do not in fact exist can be understood as too much of something. A quadriplegic lacks a continuous connection of neurons/neurotransmitters between the feet and the brain or the centers of consciousness. On the other hand, according to Delcomyn, schizophrenics exhibit an "abnormally high level of activity of dopaminergic transmitter systems." Thus schizophrenics can be understood to have an excess of neural connections.
I am not sure what interests me more, the physiological implications of the unusual functioning of the schizophrenic’s nervous system, or the sort of philosophical / spiritual implications. I am reminded of a poem I once read about a man who slept to dream of being a butterfly. When he awoke he did not know if he was a man who dreamt to be a butterfly or a butterfly who dreamt to be a man. What is more really "real" for a schizophrenic: the fantastic life they alone experience or the life the rest of the world tells them they are living?
A VERY interesting and useful connection/extension. Yes, indeed, one might regard the reported experiences of a schizophrenic as the converse of the lack of experiences reported by the quadraplegic. In the latter case, there is activity in sensory nerves but no experience; in the former there are experiences without corresponding activity in the sensory nerves (one presumes?). So, maybe we DO care about whether signals can start "in the middle of the nervous system"? And the issues this raises relate, as you suggest, not only to schizophrenia but to a whole host of questions about the meaning of "experience" and "reality" in normal, day to day existence. To be returned to. Several times. PG
However, I find this question to be redundant in the sense that I do not believe that behavior solely =brain. The distinction between soul and brain and behavior has been fuzzy and confusing up to this point. I believe strongly in a separate soul or mind. In terms of physical movement and motion, the nervous system is most definitely linked to the brain and behavior. Hormones, as well, are able to regulate and work in conjunction with the nervous system, and spark reactions in the nervous system that translate into behavior.
In short, brain=behavior=nervous system in certain ways. Definitely observable behaviors such as movement (the pinching of the quadriplegic's foot), behavior expression through hormones that send signals to the brain and cause desires and actions, and with 10^12 neurons in the brain, different combinations of neurotransmitters that can cause EXTREMELY varied behavior in people. I will still cling firm to the belief, though, that intangible events such as telepathy, love, and bonds between fellow humans have something greater than the brain or nervous system controlling them.
Alright. And the issue, as I understand it, is whether "intangible things", as opposed to "definitely observable behaviors" require something more than the brain/nervous system. So let's see whether interactions of neurons can generate something "intangible", shall we?
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