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Neurobiology and Behavior, Week 3

Paul Grobstein's picture

Welcome to the on-line forum associated with the Biology 202 at Bryn Mawr College. Its a way to keep conversations going between course meetings, and to do so in a way that makes our conversations available to other who may in turn have interesting thoughts to contribute to them. Leave whatever thoughts in progress you think might be useful to others, see what other people are thinking, and add thoughts that that in turn generates in you.

As always, you're free to write about whatever thoughts you add this week. But if you need something to get you started, are you thinking differently about the brain, about behavior, given that the smallest boxes are neurons?  that there are huge numbers of them? that every neuron is a probabilistic computer?  that "inputs" mean signals in sensory neurons and "outputs" means signals in motor neurons? that most neurons are interneurons?   

mmg's picture


When we arrived at the 'smallest boxes being nuerons' point in class last week, I eased my defenses. This was familiar turf. I have been learning about nuerons in biology for a long time. Yet, what I had always associated the nuerons with was with producing the responses to 'stimuli' - especially the motor and the sensory nuerons. One was concerned with reporting outer stimuli to the central nervous system and the other concerned with performing the actions based on the signals that the central nervous system gave. Now, I begin to comprehend how much of our behaviour is governed simply by the way neurons interact. I guess what I find intriguing then is that whether the structure of the brain (i.e. the different kinds of interconnections of the nuerons) is solely repsonsible for difference in behaviour. How much of the way the nuerons interact can be conditioned? Are there somethings that are innate to each individual? If so, is this innateness due to genes? And, how much of our behaviour is based solely on the way the internuerons are connected? Is 'free will' nothing but interactions and sparks between nuerons? I studied a bit about synapses, and to me it is all just ions moving across one dendrite to another. I don't think I want to reduce us, the human race and all its grandness, to ions moving across a bridge just yet.  

Language is innate to humans as a species - and perhaps the development of the neocortex is one of the structural reasons to explain this superiority. Does the brain then evolve to allow for such complex functions, or is the brain evolved such that these complex functions can be carried out? This fascinates me. All this while, I had entertained the idea that structure evolved to accomodate function. Yet, since so much of function is based on structure (based on the brain = behavior assumption), I wonder if it could have been the other way round.


BeccaB-C's picture


In talking about inputs, outputs, interneurons and the brain=behavior idea in class, we mentioned homeostasis behaviors, such as the intake of air to the lungs, pumping blood through ventricles and arteries, etc. These are behaviors that come about in response to inputs of which we are unconscious.

In the human visual system, there are two fairly separate pathways by which information in the visual field reaches our consciousness. 90% of visual information travels along the geniculostriate pathway, synapsing on the lateral geniculat nucleus before ending in the striate cortex (the primary visual part of the cortex). Because information reaches the visual cortex, this is what we see consciously--we are aware of it because it has reached the cortex. The other 10% of our visual information comes by way of the tectopulvinar pathway, synapsing on the pulvinar nucleus and then the thalamus. It never reaches the cortex. This allows for some patients to experience "cortical blindness;" patients with damage to the visual cortex but not the tectopulvinar pathway are completely blind as far as visual information of which they are conscious, but when something moves within their visual field, they are still able to react to a movement, without being conscious of having seen it.

Relating this to class, where do reflexive behaviors and conscious responses (outputs) to unconscious inputs fit in to the box model? At what point within the spaghetti web of interneurons does information go from unconscious to cortexual and conscious? How does this play into the brain=behavior question? I would think that it is very good evidence for brain=behavior because it provides a conscious, neural response in the form of behavior to something which, without the complex workings of the brain and neural pathways, would not warrant such a behavioral, albeit reflexive, response.

redmink's picture

Last week's lecture was

Last week's lecture was straightforward because I had no opposition to any of the ideas presented such as that there are huge numbers of neurons and that "inputs" mean signals in sensory neurons and "outputs" means signals in motor neurons.  I had been previously exposed to these concepts in textbook before.  The more freuqently I had been taught of them, the easier for me to accept them as "less wrong." 

Earlier, I had trouble progressing my position from a believer of "stimulus-response model" to that of "input-output box" becuase I had no strong conviction to abandon the former.  However, when I was presented with the observations of neurons and more traditional scientific sources with specific numbers(10^12 neurons in human body) and familiar ideas, I was convinced readily. It was interesting to observe myself changing views and reacting to the different degree depending on the different nature of obervation (me being more sensitive and willing to change by numbers and tangible, familiar sources)

Sarah Tabi's picture

Are emotions also considered a product of interneurons?

After pondering the concept that there are 1012 neurons that are interconnected to each other  in different ways in each individual makes me realize why it is possible to have different behaviors and personalities among over 6 billion people.  If there are exponential combinations of the way interneurons connect that produces output, then it is more clear as to why people have different behaviors.  Yet, if every person has a "random" combination of interneurons to produce behavior, what accounts for emotions?  Sometimes behavior is a response to emotions, so are emotions such as sadness and envy, simply a product of the way the interneurons connect?
bpyenson's picture

Many Brains, Many Minds

The most astonishing fact I learned about in the past week was the diversity of nervous systems, based on the box model.  Specifically, in humans alone, Dr. Grobstein argued that, due to the different pathways and variety in input and output and the sheer number of neurons, nearly every nervous system can be uniquely different from another.  From this observation, Dr. Grobstein implied that all of the minds that are connected to those nervous systems have the potential to maintain that kind of uniqueness also.  Indeed this creates an 'every man or woman is an island' scenario for understanding the mind.  Could the 'truth' be something less elaborate and predictable, however? 


Maybe, in spite of the diversity of nervous systems, there are less corresponding mental states/minds.  I began to think this way when thinking about these observations in an evolutionary context.  Specifically, with other trends in evolution (e.g. ammonoid suture complexity, bauplan diversity), the fossil record and molecular genetics suggest that although higher complexity is achieved, as shown by a diversity of different kinds of a feature shown in different species, often this diversity narrows over time, due to evolutionary and ecological constraints.  I'm thinking of Steven Jay Gould's argument in particular, where he cites that the diversity of organisms is not some teliological attempt towards more complexity, but in fact is a desire for more simplicity, which will then allow one more flexibility to adapt to an environment.  I'm throwing all these observations on the table simply to acknowledge that perhaps our incredibly diverse nervous systems may not give rise to equally diverse minds, and that maybe we're striving towards more uniformity than more diversity?

jrlewis's picture

In class this week, we

In class this week, we learned something about the structure of nerves.  Nerves are a bundle of axons, cell bodies and dendrites are absent.  They carry signals from one location in the nervous system to another in the body.  These signals can travel in both directions along nerves.  Next, I began thinking about what can go wrong with nerves.  Particularly how to make sense of a herniated disk.  A herniated disk occurs when the spinal disk slips out of place and pushes against spinal nerves.  This situation results in a significant amount of pain, amongst other things.   So the pain is a symptom of an anatomical problem. What I would like to know about all this is how do pain medications work?  Especially, drugs like vicodin and percoset.   How do these chemicals interact with the nervous system and affect signaling?  I am hoping for an explanation beyond basic biochemistry...

Olufemi.Nazsira's picture

Nervous System and Genetics?

What I am still grappling with is if the interneuron interactions which occur within the nervous system are responsible for our behavior, how do we explain the significance of genetics in shaping our personalities? Often we inherit our parents' traits, and occasionally even grandparents' as genes can skip generations; for instance I know that to a certain extent, a few of my sisters (self included) inherited our father's temper. We know that certain behaviors are genetic while others are learned; the notion that our dispositions might have been influenced by our father's behavior seems logical, but he passed while we were still infants, so this problematizes that quite a bit. So, as far as genetic behavior is concerned, how does this intersect with the concept of our nervous system being solely/primarily responsible for our behavior? Even if we do in fact possess all of the same essential elements, difference in behavior must be attributed to more than merely the arrangement of our neurons, right?

The following article might help clarify my confusion:  

While Professor Tim Spector, of the Twin Research Unit at St Thomas' Hospital, London, thinks there might be evidence of a genetic component to infidelity, he also supplies that there is no one singular gene but rather that several genes working in concert is probably the culprit for such behavior.

To counter, Dr. Petra Boynton emphasizes that is it difficult to discern learned and inherited behavior and that infidelity is more likely to be attributed to socialization and previous experiences than genetics.

fquadri's picture

So maybe Dickinson had a point...

So maybe Dickinson is looking at me right now going "I told you so".

This box theory is proving that it really is the physical matter of the brain that is controlling our behavior. It is as wide than the sky in the sense that our brain has a wide capacity to hold and process all sorts of information and as the nerves in our eyes are responsible for seeing the sky. However the content of the brain isn't the only thing that is important; by looking at the brains of different animals, size and structure are also critical to behavior. We behave very differently from a frog, not because we have different material from them but because that material is structured differently. This makes a very strong case that brain=behavior, along with the face that about 99% of the brain's neurons are interneurons (receive and send signals within the nervous system where the outside world has no effect), that Dickinson's view holds true. But I've been a believer that the "mind" (emotions, consciousness, etc.) is  embedded within the "brain" (physical matter). Perhaps this is the begginning to finding that proof, or at least an answer? 

BMCsoccer01's picture

Morphology in the Brain: A Sand on the topic of Sexuality

Since we have been discussing the possibility of each person's brain being uniquely structured and individually based upon the ways in which one processes their inputs to make outputs, I thought about the issue of sexual preference. In proving that there are differences structurally between male and female brains, one can argue that there is a possibility that a man can be born more with a "female" mind rather than a "male" mind.  What I mean to say is that a man could receive inputs and create outputs more similarly to a woman than a fellow male counterpart.
Those who believe that sexual preference is not biological based rather is the outcome of choice, should think of the mind uniquely structured based on fate and a continuous battle between society on what is manly or womanly as opposed to an outcome of freewill. What is to be said about those who are born hermaphrodite- in order to say that one is a man or woman, isn't it a more concrete decision to observe how the individual processes information (deals with inputs & outputs) in order to label them a certain sex rather than observing their behavior which is influenced by society (a choice on how to act)?       
kenglander's picture

inputs and outputs

Along with many other people in our class, I question our definitions of “input” and “output,” or at least how the definitions are being utilized in our discussions.  I do not think that inputs need to be tangible, nor temporally concurrent. Rather, actions (outputs) may result from past experiences based on perceived similarities between the past and present situations. By restricting ourselves to the most concrete of inputs I think we might limit our understanding of the brain and how we generate novel ideas or grasp abstract concepts. Furthermore, we would also be neglecting the role of interneurons; it seems highly unlikely that their sole function is to send information to other neurons. Surely there must be some more complex role of interpretation or mediation that goes on within our brains.
hope's picture

so here's something I've

so here's something I've been wondering,

that leach that they took the nervous system out of, how old was it? had it lived a full leach life? had leach experiences? could those leach experiences have been responsable for the activity of its nervous system after it was removed? if the leachhad been just freshly born when its nervous system had been removed, or if somehow a leach system was cloned and never put in a leach body would it still produce output? in more general terms, can a nervous system produce output in the complete absense of any previous input? If so, then what would be the purpose of learning other than to standardize the output of all of our brains?

ddl's picture

Variations Within the Structure of the Brain

I was personally very interested in the discussions that we had about the morphological differences that exist between not only the brains of different species, but also between those of different genders within organisms of the same species.  What is most perplexing to me is the stimulus which causes these differences.  The traditional scientific approach would lead one to believe that this morphological change was sparked by a chance mutation in one’s genetic makeup.  However, what is to say that one’s thinking and own collection of thoughts was not the impetus for this change in morphology.  By pushing the brink of one’s traditional means of thinking or attempting to focus one’s mental capacities in particular ways, could an individual alter the physical structure of his or her brain.   From the discussions that we have had thus far in class, I am convinced that this may be entirely possible.     

Adam Zakheim's picture


By the end of Thursday's class, it was concluded that the nervous system is almost entirely composed of interneurons, which receive and promulgate signals in the neocortex. This suggests that lots of responses are generated from with in the nervous system and hence, these findings are consistent with Dickinson's argument. Moreover, this idea also supports the "modified box with in a box" model, since the brain must be highly organized in order to accommodate the signals from the 10^12 (x 99.99 %) number of neurons.As I continue to think about the “brain = behavior” argument, it becomes more apparent that the architecture of the brain is largely responsible for how we behave. Comparing the neural anatomy of several different animals demonstrated that different animals have different neural systems (although they share a similar pattern, i.e. spinal chord / medulla / midbrain / diencephalons / forebrain). This raised the question; do similar organisms have different brains? Since the architecture of the brain is dependent upon such a vast number of neurons, it would make sense that differences would frequently arise. But where and when do these difference occur.  If we are to assess this question, I believe it is essential to ascertain when brain development begins. The brain develops during gastrulation, but when do prenatal animals begin to actually think?
kdillard's picture

Interneurons and pathways

I have been thinking a lot about what controls the nervous system. For such a complicated and interconnected system, how is it replicated in a nearly identical fashion for each individual? More importantly, how do individual nerves know where to go and which muscles to enervate? In class on Thursday, we were talking about a specific nerve that travels from the base of the spinal chord all the way down to the foot. How does this nerve know exactly where to travel? What is controlling and directing that nerve, if not the nervous system? Also, if differences in behavior are merely the result of different connections and different pathways between interneurons, then what accounts for the development of a learned behavior? If I consciously decide that I am no longer going to be bothered by something that has upset me in the past, and I work every day at not being irritated when that specific thing happens until I reach the point where I am no longer bothered, then have I changed a pathway? If so, how does that change occur? If not, what accounts for the change in behavior?
bbaum's picture

When we were discussing

When we were discussing neuron function and structure I wasvery interested in the distinction between white and grey matter. I’ve seenmany brain scans before and I’ve never understood the color differences (I hadalways thought they represented differences in neuron activity). Learning aboutwhite and grey matter made me interested in the differences between these twobrain regions. If the neocortex consists of both white and grey matter, itshould be able to send messages all over the body via the axon bundles. If theneocortex has access to regions outside the nervous system, it would suggestthat human beings, and other mammals have fully integrated the neocortex intoour functioning. Unlike other adaptations that species have undergone, it seemsthat the neocortex has now become essential to our survival, not just ourdominance over other species. I think that the neocortex is capable ofperforming tasks independently, but it also needs messages from other portionsof the nervous system, as well as the body. So, if the neocortex were removedfrom the human body, it would create no useful signals. But if the wholenervous system were placed on a Petri dish, it would continue to form signals.


It would make sense to me that individuals are born with ahigh percent of grey matter, and a smaller percentage of white matter. Humansare born with the ability to shape their neural pathways in a number of ways.We don’t have the ability to create infinite numbers of pathways because oflimitations placed on us by genetics and environment, but we do have a widerange of opportunities for pruning. Once we had established our neuralconnections and created nerves, the white matter would become more prevalent.At first, I believed that it would be more beneficial to  have a higher percentage of gray matterin the brain because it meant that learning would be more flexible, but aftersome consideration, I now believe that it is most beneficial to establish whitematter. In fact, individuals with disorders such as autism are known to have ahigher proportional of gray matter in areas of the neocortex (

hamsterjacky's picture

My internal voice

In class we discussed the self generated outputs that our brain creates, and this reminded me of my internal voice. She sounds a lot like me, and helps me rationalize about a lot of things like wants vs. needs, what assignments I need to do instead of playing video games, etc. So my internal voice keeps me on track, so to say.

However, is this a self generated output or my unconscious reacting to daily stresses such as homework, budgeting, family problems, etc? my internal voice and I have out own conversations - I promise I don't have disassociative personality disorder - I wouldn't know about my internal voice then, now would I? However, what is it? Is it my unconscious? My neurons firing up because they're bored? Or is it something that just doesn't exist but I consider to be a part of me?

Bo-Rin Kim's picture

the relationship between physical and nonphysical

The idea that information can alter the brain fascinates me. In this observation we once again see the connection between physical matter and a nonphysical entity such as information. How can something that is not physical impose change on something that is? It seems as if the two are of different dimensions and I cannot understand how the interaction between these two is made possible. This brings me back to the question of how consciousness arises from physical matter, which also addresses this idea of how the physical and nonphysical interact.
SandraGandarez's picture


Learning about how many boxes each person can be broken down into surprised me. I obviously know that everyone is different, whether it is physically or mentally, but I never stopped to think just how many different people there are. With about 1,000,000,000,000 neurons in our bodies that can account for differences, it's mind-blowing to realize. Our planet can replicate multiple times and still have everyone occupying it be different. The thing that bothers me is that if me and another person only have a difference in one or two neurons, will it really make that big a difference? If so, then how?

jwiltsee's picture

Nervous System

I think I may have some difficulty explaining my thoughts clearly and coherently, but I want to talk about a negative circumstance that I'm not sure I fully understand now relating to the function of the nervous system.  We learned that the nervous system is >99.99% inter neurons.  Also, that the neurons are made up of boxes within boxes that receive inputs and transmit outputs. 

What I'm interested in learning is the effect of different diseases and injuries that lead to various forms of degeneration of the nervous system.  I wonder about the effect on the various neurons and the quantity/abilities of the boxes.  Which type of the three neurons will be most adversely effected. 

Go to the far extreme of degenerative diseases, total loss of bodily functions.  From here I believe that Emily Dickinson's view is strengthened in contrast to Descartes'.  Although you are unable to move your body, you still have the ability to think, have urges and feelings.  Using Dickinson's theory your mind is still at work and the world is what you imagine it to be, and you decide your "actions" from your mind.  Whereas with Descartes, you would be mentally and physically incapicitated since your nervous system would be shut down.   

drichard's picture

On reality and creativity

As the class conversation progresses, it seems more and more evident that humans, due to their self-awareness, engage reality in a give and take relationship. Matter and the laws of science come to us, we understand and master them, and then we manipulate them. The law of gravity, for example, is a basic law of nature that revealed itself to us (through that ever-important apple that bruised Sir Isaac Newton's head, and in turn left a mark on the head of humanity). We quantified it through physics and mathematics (which also "came to us"), and we manipulated it (as we do on a daily basis, from the dump truck to the study of aeronautics). This manipulation is where creativity comes into play. 

Someone is class, I'm sorry  I don't know your name, brought up Da Vinci and his flying machine. Certainly Da Vinci was a man of astounding intelligence and his machine was as novel an idea as they come, but his creativity existed not in some fantastic, original output lacking an input. It existed in his ability to combine and manipulate myriad inputs he perceived over time. In other words, his creative output was in fact a function of numerous inputs throughout his life: his education in mathematics and physics, his acquired knowledge of craftmanship, his love of birds (I don't know this for sure. Just an example) etc. Creativity comes down to an ability to combine. Creative ideas are a function of memory and the human ability to problem solve.

This leaves open the possibility that some people are naturally more creative than others as they have more accurate memories and can combine ideas and concepts more fluidly. Some people are better at thinking "outside the box" (pun intended).

This argument relates to the idea of outputs without inputs. Do they really exist?  Or is there just a time lapse between certain inputs and their respective processing? Some inputs may not generate a direct and immediate output. Also, various inputs (i.e. observations that we add to our grand summary, our concept of reality) can be called upon long after they have been perceived in a creative combination of sorts (such as Da Vinci's flying machine).

Going forward, I am very interested in the effect language has on the interpretation of matter and general reality and, in turn, how this effect plays into creativity. Language is one of the pillars of every society, thus it has a dramatic effect on how one looks at the world. Prof. Grobstein, if you are reading this, any suggestions for books on language and/or creativity? Thanks.

mmg's picture

You might want to look at

You might want to look at Steven Pinker and Noam Chomsky's works. Both write about language and the brain. Pinker wrote The Language Instinct, might be useful.
ilja's picture

looking at the bigger boxes

We have talked about several things in our discussion: about boxes in boxes, about neurons as the smallest boxes, about their input and output, about the complexity of all these neurons and how they might be able to explain the differences between individuals and the differences between different species. Our NS seems to be very complex and if it is responsible for our behavior, or can explain our behavior I think that maybe we have to look at some of the bigger boxes first (if we want to be able to start anywhere). Because these bigger boxes might be able to give us some information of bigger processes working in the body, since one neuron (although very important) will not explain thinking or feeling etc as a whole.The other part of our discussion that is still on my mind is how can we change our behavior? Do we change our brains (can we find the reason for our differences solely in what’s in our head?) or can our environment help us change? And if it is a combination of both, how much is determined by our environment and how much is determined by our firing neurons? Or is this just a question of the chicken and the egg? Or of nature vs nurture?


aybala50's picture


When we first started talking about the box model it intrigued me and I really liked thinking about it being "true". I mean, it made sense, but to some extent felt slightly unreal possibly because I was never taught about "boxes" in the body. Last class when we connected what I knew about the body, or the nervous system, with the boxes the idea made a lot more sense. The percentages of interneurons also supported the box idea from Dickinson's point of view. Overall I thought last class was a good discussion that connected a few loose ends for me. 
Leah Bonnell's picture

More on thought

When people talk about thinking they often use the term "neurons firing," but given what we're learnt in class I'm not sure how thought process connects to neurons. Do thoughts develop in some type of complex interconnected chain like neurons? Do thoughts have some type of material substance in the brain? When I think that brain= behavior I imagine that thoughts must made out of some material substance. But from what? I can't imagine that neurotransmitters are responsible for the complexity and breadth of human thought, but at the same time I feel like the complexity of neuron architecture may be involved. When patients are given tasks, different areas of the brain will light up according to what they are doing. So maybe thinking involves different parts of the brain, like the frontal lobe and temporal lobe, interacting with each other. I looked this up online and it seems like it may be true. I came across a study that argued that creative thought comes from areas of the brain connecting that normally would not connect. I think this makes sense, especially given what I've learnt about neuron architecture and individuality. Differences in neuron architecture would allow areas of the brain to connect in unique ways, allowing for individuality and creative thought.


eglaser's picture

Thinking about thinking

As we begin to discuss the neocortex and the concept of 'higher thinking' or thinking about thinking, I am intrigued by the thought of how that thought process works. Is a neocortex all that is required for 'higher thinking'? If so, why have we developed it where other mammals have not? Or have they? I understand how the brain is shaped by our personal experiances and behaviors but how does thinking alter the brain?

Simple thought is not necessarily considered to be a behavior so, does it have an impact on the structure of the brain? Can you detect thoughts in the brain with an MRI? What is the physiology of a thought?

Lisa B.'s picture

The smallest boxes

The continuing theme of every discussion seems to be the remarkable demands placed on the brain. This week we learned that the smallest of building blocks are neurons that are highly specialized for signal transmission in the nervous system. Although they are only micrometers in diameter neurons respond to information from the outside world and form new connections. Most neuron activity is not the result of outside stimuli, but the activity inside the nervous system.

Dickinson wrote that the brain is wider than the sky, but humans still suffer devastating neuronal loss.  The box theory fails to explain diseases of old age. If the nervous system is dependent on the interconnections between neurons, why not circumnavigate the destructed areas of the brain? Could neural stem cells replace malfunctioning boxes to avoid memory loss associated with Alzheimer's?

Sam Beebout's picture

mammal love

my gramma forwarded this to me...but I think it speaks to our conversation about what some of the base similarities might be between mammals. 


nafisam's picture

In class on Thursday, it

In class on Thursday, it was mentioned that much of our actions, or I suppose what would be considered outputs, are a result of activity generated from within the nervous system. How does the nervous system generate an input all on its own? Is there something such as an input generating an input? Or perhaps a stimulus for an input? We defined input to the nervous system as something that activates sensory neurons. So perhaps sensory neurons are responsible for activating sensory neurons, which reminds me of the idea of boxes going all the way down forever…

  Also if most of our actions are dictated from within the nervous system, does this mean that everything outside the brain is just a construct of our imagination? Perhaps Dickinson would think so. I have a hard time accepting the implications of this, in the fact that physical objects are seen almost uniformly by  all people. Everyone can identify a chair, and has associated the image of a chair with certain actions, such as sitting down. Although everyone has a unique brain, why do we behave in a predictable manner in specific situations? It would seem that since there are an almost infinite amount of combinations of neurons, which are each their own “computer”, that all humans would be vastly different, and any foundations, such as social norms, would not exist. Given the fact that they do exist, perhaps outside influences such as culture and social norms tend to even things out, and account for the similarities in behavior among specific groups of people. But in general given the variations in neuron architecture that exist between humans, it's pretty mind boggling to think we can all co-exist (for the most part).

Bo-Rin Kim's picture

shaping the brain

One of the reasons why I had a hard time agreeing with Dickinson’s perspective that the brain constructs all reality was that people seem to agree on a lot of reality.  Humans seem to “construct” a lot of the same realities, especially physical realities like the chair example. It seems unlikely that we would be able to construct such similar things when our brains are known to be so unique.
We learned in class that the architectural differences of neurons are what produce different parts of the nervous system and different, individualistic brains. We also discussed how “information” could shape the brain and influence the organization and properties of neurons. So I do think that social and cultural influences or information shape the brains of groups of people. When people adapt a certain set of morals or certain way of thinking, they must also induce change in their neuron organization. This said, I do not think there is one specific neuron organization that leads to a thought. I think a thought can be processed or created through several different pathways, using several different neurons. The same output can be created from different inputs and different input processing pathways. So while cultures/society/religion and other large influential forces can impact how people think and how their neurons are organized, I don’t think this means that people adapt the same neuron architecture. People’s unique brain structures can be altered by these external influences to encompass the thoughts and beliefs promoted by  their larger social environment.
jlustick's picture

Some thoughts

To begin with, I am interested in our continuous conversation regarding the boxes that spontaneously generate outputs. It seems like these boxes still receive some sort of input, it's just not an input that comes from outside the nervous system. In other words the input to these boxes does not conform to our class definition of input as something that activates sensory neurons (which have dendrites outside NS). The sensory neurons accounts for physical sensations-touch, smell, taste, etc., but what about emotional sensations? How is it that people feel depressed? Does that require an input from outside the nervous system? How do we explain the connection between hormones-which are present in the brain-and our behavior? Another question I have is where dreams fit in to the box? Are sensations felt during dreams based on memories of past sensations? If so, then how come people can feel like they are flying, a sensation that they have never actually had? Are dreams an example of an output produced by a box with no inputs?

On a different note, I was thinking back to Thursday's discussion regarding the three different types of neurons and how the vast majority of neurons are inter-neurons. I was wondering if it would be possible to have an organism with only motor and sensory neurons? Would this be a "brainless" or "mindless" organism?  

Max86's picture

Thought Experiments

First of all, depression is a very interesting point. What can one make of severe, clinical depression that seems to occur without rhyme or reason? Simply a self-generative interneuron action?

Additionally, I can't imagine there being an organism without interneurons based on what I heard in class. Are interneurons not the conduits that facilitate all nervous activity, sensory and motor nerves as well as cognitive, self-generative activity? 

Here is an interesting article I found that deals with the thought experiment: How might an organism without receptors, that is, without sensory neurons function?

The article discusses "mysterious induction" and "energy fields" as fundamental to the proposed motor/interneuron system. 

At the very least, I thought it was interesting the way the author expresses a notion of motor/sensory neurons as operating concomitantly in all perception, behavior being dependent upon a subjectively motor-driven perception of an environment. 


Sam Beebout's picture

Beyond thinking about the

Beyond thinking about the difference in the structure of the brain from animal to animal and the influence that has on behavior, I am interested in the way in which the structure of brains differs from person to person.

I was most interested in the observation that 99.9% of neurons are interneurons so that Dickinson's argument for the constructedness of our surroundings, the creation of experiences in our brain, seemed to be supported. There is the additional observation, then, that all of the neurons in the neocortex are interneurons.

Somebody asked on last week's forum what the purpose of memory is. I always think about the quote that you only ever see the same thing once, and the idea that from that point on every observation, even of the exact same thing, will be through the lens of the experience before that. In this way, if this statement is correct (and the ratio of interneurons to sensory/motor neurons suggest that it may be) then our experiences are always simultaneously memories. 

The neocortex is unique to mammals, and in class last week we started a conversation about what distinguished mammals with a neocortex from other animal groups. Is there a more balanced ratio between sensory and motor neurons and interneurons in animals whose nervous systems do not have a neocortex? 


Brie Stark's picture

Just Thoughts

Throughout this week’s discussion, which was very interesting in considering neurons on a level that I had not thought about before, I had several questions come to mind.  In the beginning of the class, we discussed the vague notion that brain = behavior.  While I took this to be a satisfactory thought, I didn’t understand the complicated inner-workings of the equation.  Throughout the discussion of the differences in brains of differing species, especially those of mammalian brains with a neocortex, I found that it was easy to accept the notion that brain does equal behavior.  However, we then brought individuals of the same species into the question, which was where I would have to add a bit to the equation.  It would make more sense to me, and seem a bit more pinpointed and thorough, if instead we said that neuron architecture = behavior, in relation to organisms of the same species.  Because the brains of the organisms have the same overall structure and only the neuron patterns differ, this seems logically superior. 

Also, humoring the notion that most creatures evolved from a common primordial ‘goop,’ I have to wonder if the common ancestor once possessed a neocortex which was selected against in all other organisms except mammals.  I wonder if a vestigial neocortex could’ve been found in reptiles upon their immediate creation, and if that neocortex faded in time because of lack of need or environmental changes.  This would definitely pose many questions on whether behaviors have changed over time because of this.  In the terms of human evolution, it is also interesting how our neocortex—which has probably developed to a larger state over the time of evolution—began to increase in its mass and its functions.           

In the beginning, no doubt that neuron architecture did equal behavior—but it is interesting to think that, because the human race has evolved so much (as far as we know), the neurons and the brain have likewise evolved, creating new behaviors.  I wonder if the overall structure of the neuron has itself changed over time, like that of the brain.  If so, perhaps we could have a more direct link to understanding the behaviors of our past ancestors if we could somehow coordinate this evolutionary change and determine the structure of the primordial neuron of the human.

OrganizedKhaos's picture

Born an Individual?

     After our talk on Tuesday I felt really great knowing that no one else had my brain. It made me think about this struggle for individuality that everyone has or certain people focus their entire lives on. I first that well since none of us have the same brain does that not already make us individual enough? but then I come to think that maybe the struggle for individuality is not so much about the contruction of the different parts of our brains but more so about the way we may share similar outputs to certain words, situations, etc. That led to the idea or myth of twins sharing thoughts or people sharing thoughts. What is that does that mean that certain parts of peoples brains can be similar? Or does that too also account for cultures and the environment in which they exist? Ultimately does anyone ever reach this state of "individuality" and what is it really if not mental?

     Also, looking at the idea of the bigest box and what seems to be the input for that I would have to agree that the outside world and everthing around it is an inout. Touch, taste, smell, things that we see, feel, etc. This makes sense because the closest way we could replicate taking out of the nervouse system from all types of input (like the leech experiment) is sensory deprivation. If you are removing all forms of sense then in a way you are ridding all external inputs right?

Paul Grobstein's picture

Apologies and ...

Sorry, should have gotten this forum up earlier. See Brain is NOT a computer? Will be sure to have forums available by the end of class Tuesday in weeks to come.