Neurobiology and Behavior, Week 7

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.

You're free to write about whatever came into your mind this week, but if you need something to get you started: what have we learned about the brain, about behavior, from studying neuronal signals?  What more do we need to make sense of all of human behavior/experience? 

 

yml's picture

Brain, brain, brain...

* I thought I posted a reaction, but can’t find it in here. So I’ve posted again.

Since this is mid-term, I want to write kind of a midterm reaction post. I was just amazed by how much is going on in our head and how much of them happen unconsciously. I’m the type of person who needs to know what’s going on around me, why it’s happening, and have control over them. However, as I learned about brain and behavior for 6~7 weeks now, I realize how much I don’t have control over my actions, behaviors, thoughts, etc. Also, it’s irony how brain works is so effortless (at least for people without disabilities), but understanding how that worked takes lots of effort to study and understand. After all, my brain knows all that. Otherwise, how would it have done those? But I don’t know how they happened! I need to learn how my brain worked by looking at other people’s brain activity or even other animals’. I could get really frustrated by this fact! But I will rather try to learn more and understand better. 

 

meroberts's picture

Signals and phantom limb

Neuronal signals make all behavior possible. These signals are the links between the brain and behavior. These signals are also diverse and versatile. In class we have discussed the possibility that the signals are all the same and the reason there is such a variation in behaviors, or outputs, is due to the diversity of areas in which the signal occurs. For example, when someone touches their hand to a hot surface, a signal alerts their brain that its hand is in trouble. But before that signal can be interpreted and responded to by the brain, another (similar) signal inspires the reflexive behavior of the hand in response to the heat. The signal was the same in both cases, but they engendered different responses because of the location of the electrochemical impulse.

This could be related to people experiencing phantom limb syndrome. In phantom limb syndrome, people feel pain in the limb that has been lost. This is because the area of the motor cortex that is responsible for the movement of the missing limb has been taken over to control another region of the body. Thus, the people still experience sensation, usually pain, in the missing limb because those same neurons are firing. The signal is the same, but the region of the body being "controlled" is different. This produces feelings of pain in the missing limb instead of movement in the limb that is still attached. This explains how the same signal can be responsible for the multitude of functions that humans have to accomplish every day to survive.

MEL's picture

Neuronal Signals

 

By studying neuronal signals we have learned about the complex inner working of the brain. It is very interesting to know they way in which the human nervous system works. The fact that our nervous system is controlled by chemical processes is a bit scary. I don’t like knowing that all of my actions are controlled by a semi-permeable membrane and a concentration gradient.  I find the idea that our reality is limited by the proteins that produce the permeability changes fascinating. There are so many things in the world that we cannot experience because we don’t have the proteins that produce permeability changes in their presence.

After learning about neuronal signals I started thinking about more human actions and how they are controlled by these signals. How do neuronal signals relate to thought and emotion? In terms of thinking, when a neuronal signal is propagated, is the output a sound, a word, or a sentence? How is thought created from neuronal signals?  In order to make sense of all of human behavior and experience, I think we need to explain how neuronal signals relate to emotion, thought, and other complex human actions.

 

Hannah Silverblank's picture

In a little blurb from the

In a little blurb from the NY Times blog called "Brain Science vs. Criminal Law," the author asks readers, "Advances in neuroscience put it increasingly in conflict with criminal law: If all our mental states can ultimately be reduced to neurophysiological conditions, and there is really no such thing as free will, how can people be held accountable for crimes?" (http://ideas.blogs.nytimes.com/2010/03/04/brain-science-vs-criminal-law/?pagemode=print&scp=6&sq=neuro&st=cse)

While asking these kinds of questions seems like a radical departure from traditional thought about law and culpability, it's true that the law has integrated certain "scientific" factors into our understanding and ruling of justice. Neurobiologically, we've come about as far as it gets since the U.S. Constitution was written, and the author of the NY Times blurb seems to think that the brain=behavior philosophy undermines the applicability of a vocabulary that includes words like "liberty" and "freedom." If we do not possess the liberty and freedom of traditional notions of free will and active choice, do we need to reevaluate the bend of our legal terminology and criteria?

 

When neuroscientists obtain a role in the ruling of justice, the court is transformed and the subtleties of cases can be deepened. For example, a greater understanding of a "psychopathic" brain may transform the assignment of guilt (a term whose usefulness could disappear in a world of self-less behavior, as proposed by the NY Times blurb) in certain court cases. In observing a psychopathic murderer, neuroscientist Kent Kiehl says to the jury, “'There are abnormalities in his brain function.'" Psychopaths make choices, he acknowledged, but “those choices are not necessarily informed by emotion in the same way ours are."

(http://www.miller-mccune.com/legal-affairs/a-mind-of-crime-8440/)

 

I think I'd like to know more about the physical processes that occur when decisions are made, so that I can more deeply understand the interplay between physiological occurrences and human agency. The idea of randomness of choice vaguely proposed by the NY Times blurb seemed unsatisfactory and lacking depth. I'm not particularly attached to any cohesive notion of my own self-hood, or of my absolute agency in my engagements, but I find it hard to believe that there is no character to the randomness, or no pattern in the chance of choice that unifies the actions of an individual in such a way that a legal system based on justice, freedom, liberty, and guilt would cease to retain its functionality.

 

AndyMittelman's picture

chemical signals and learning

  

            Like Saba mentioned earlier, I am excited to learn more about the role of proteins in our perception of the world. The more bio I learn, the more it seems that everything is about proteins. You made a point that seems particularly true to me- “There can be so much going on and taking place in a room that we would never know about.” Could the role of (or lack of) proteins explain why some people are particularly perceptive in some regards but less in tune with others?

The description of neuronal signals as a computer does seem a little overwhelming to me at first. I have a hard time internalizing the “hard wiring” we have inside our heads. I still cannot fully accept that our cognition is caused by these rather primitive-looking chemical synapses. If inhibition is a chemical process, when we experience a sedating effect that is just a chemical sequence occurring within us. This actually seems somewhat empowering—if we could train ourselves to more fully control the chemical processes within us, we could cause significant shifts in our body (ie mood, physical state, etc). Similarly, I wonder if it will someday be possible to “learn” just from a rapid flow of information into our bodies or via injection (I’m thinking of when Trinity learns how to fly a helicopter in 5 seconds during “The Matrix”). Would it really be such a good thing if we had such cognizant control over our nervous system? As Schmeltz pointed out, this might lead to the potential for over-control, wherein every action is overly-calculated. At this point, I’m not sure we’d really be human anymore!

            On a side note, I’m super thrilled to see that Carrie and Emily have also adopted the logo of the best sports team around.

kdilliplan's picture

Shades of Grey

Over the break, I read Shades of Grey, a new novel by Jasper Fforde.  I may expand on this post later and write a full commentary about this book, but for now I’ll stick to its relevance to our discussions.  The book begins with a quote from Alfred North Whitehead: “There is no light or colour as a fact in external nature.  There is merely motion of material…. When the light enters your eyes and falls on the retina, there is motion of material.  Then your nerves are affected and your brain is affected, and again this is merely motion of material.… The mind in apprehending experiences sensations which, properly speaking, are qualities of the mind alone.” I was struck by how this sounds a lot like what we’ve been talking about in class.  On a basic level, neuronal function is quite simple, but humans are capable of experiencing a vast array of senses, emotions, memories, etc.  But there is still much we can’t and don’t experience. In the world of this book, set in an indefinite post-apocalyptic future, class structure is determined by the amount of color an individual is able to perceive. Those who can see purple are the heads of society, those who can see yellow or green are lower down the ladder, those who can see red are lower still, but those who can see no color (only shades of grey) are at the bottom.  There also exists, in this world, artificial color that can be seen by anyone.  Color is also used medicinally and as weapons: by looking at a sample of the right hue, a person can be cured of illness, be made blissfully ecstatic, fall unconscious, or simply drop dead. The book also suggests that color perception is heritable (a Red and a Blue could have a child that is Purple) but not fixed generation to generation (over time, families that once had strong color perception can become Grey, and a Grey family could gain color vision without outside influence).

            While it may seem silly to us, this use of color isn’t as fictional as it might seem. Colors are known to affect people’s moods. Color perception can vary tremendously between individuals. It is not so far-fetched to think that this kind of world could be possible, since color is a construct of our minds and as such its perception could be used, abused and changed. All it would take to make a population of humans with limited and variable color vision would be heritable differences in color receptors and a government-controlled method of testing for said differences.  Similarly, it is possible that rewiring the nervous system (or in fact learning more about the nervous system as it is now) could make possible the kind of dramatic responses to color that are seen in the book.  If everything is a result of “motion of material” virtually anything is possible. 

Jeanette Bates's picture

Interpretation

This sounds like a fascinating book; I think that you've given me a new summer reading book. You're comment has helped remind me that there is a big difference between what we receive and how we interpret it.

cschoonover's picture

Moving Forward

 After class on Thursday, I feel as though we have many of the tools that are needed to make sense of the human brain and human behavior. We know how action potentials are generated (either within neurons or by events outside the nervous system) and how they propagate. We also have an understanding of how signals interact with each other and how neurons communicate with each other. At the end of class we used the analogy of a computer to describe neurons: they take in a lot of information, they integrate the information, and then release the information, and this whole process is constantly altered by its own activity. However, we said that the brain is not a computer, because it is changed by the past. This means that learning and memory are a fundamental part of activating this entire system. Given this notion of how the brain functions, I feel we still need more tools to evaluate the human brain, and thus human behavior. I’m sure we all know that learning how to ride a bike requires a lot of practice. But once we get it, we can do it all the time and it becomes almost second nature. I wonder how we get to this place. Is it all muscle memory? And what about the other activities, such as sports and hobbies, we all enjoy? Certainly that can’t all be the result of muscle memory. So what else is going on in the brain when we learn to do these things? Memory also seems to be pretty complicated. We can’t remember the first few years of our lives, but we definitely had learning experiences then. And why do certain parts of the past get fuzzy after some time has passed? Why can’t we remember everything with a high degree of accuracy? This inability to remember everything may be due in part to information overload that would occur if this were possible. But what is going on in the brain with the things we do remember with such clarity? I wonder if the neuronal connections involved with memory degrade over time or if there is some other mechanism at work. In sum, I guess I feel as though we still have a ways to go in understanding the human brain, but I think with our understanding of action potentials we have a great base from which to move forward. 

AndyMittelman's picture

 You make an interesting

 You make an interesting point about why we remember some things very well but not others. In a computer, the more activated pathways don’t really seem to become easier (my computer does not get faster the more I reboot it, rather, more of the contrary). Our neurotransmitter pathways, however, are malleable. Also, it’s unfortunate that traumatic events seemed to be “burned” in our memory, even though we might not want to remember them. Perhaps an evolutionary response. If we had a traumatic event, it would be to our advantage (evolution-wise) to remember it so we could avoid a repeat in the future.

natmackow's picture

Receptors and Chemicals in the brain

At the end of class on Thursday we discussed the notion that synaptic activity varies with time. The amount of neurotransmitter released and the number of receptors for that chemical all may change with repeated use (or disuse).  I was intrigued by this because of its parallel to drug use and withdrawal. For example, when caffeine is consumed and present in the brain, it binds to the receptor for the neurotransmitter adenosine, which serves to regulate blood pressure among other things. An increase in the amount of caffeine one consumes (the amount of this chemical that is consistently present in the brain) is then related to an increase in the amount of adenosine receptors present. This is known as tolerance. If a person were to stop consuming caffeine for a prolonged period of time, the receptors would initially still be present and a larger amount of adenosine than usual would bind to these receptors. Thus, caffeine withdrawal effects (headache, nausea) are in fact caused by the binding of adenosine to these receptors in the absence of caffeine.

I wonder whether other chemicals, such as the endorphins released after long, uninterrupted workouts, have the same effect as caffeine in creating more receptors in the brain. Endorphins resemble opiates in their ability to block pain and cause one to feel well and happy. Should it be expected than an individual who exercises everyday has a greater number of receptors for endorphins than a person who rarely exercises? Are they happier? What would happen to that individual if they stopped exercising suddenly for a prolonged period of time? Can these individuals experience withdrawals from strenuous exercise (pain, depression)? Would some other chemicals begin to bind to the numerous receptors causing other symptoms? Or, perhaps the amount of endorphins produced is small and the effects are fleeting (limited to a short period of time after exercise). Perhaps a lack of exercise would cause no observable detriment in one's behavior.

 

Raven's picture

I question the I-function

 So after class I feel like many people have different interpretations of what the I-function is. When people comment on the I-function some say it is the sense of being self-aware, or the ability to question one's existence, or the ability of the mind to be separate from the nervous system. I do not know what I believe. Not that there is one definition of course. 

I was wondering if there are any disorders where the action potential doesn't propagate in the appropriate direction?

It is interesting how our senses makeup our "sense" if reality. Altering the senses alters one's sense of reality. 

 

How do we behave without the numerous inhibitory synapses? Would we be able to make decisions if we did not have inhibitory synapses? 

Would we be self aware if we didn't have these inhibitory synapses because being self aware would mean we are able to make decisions on how to behave?Furthermore, how much of this inhibition is influenced by environment(family, society, oneself)?

 

Colette's picture

          We are unaware,

          We are unaware, i.e. unconscious of many things our body is doing. Our brain is the main control system; however, many of the actions it directs especially those that allow our body to care for itself take place below the level of consciousness. The basic units of our nervous system including our brain are neurons which transmit signals as action potentials. I was astounded to learn that action potentials were similar to electrical currents produced by a battery. How a mechanism seemingly so simple can manage complex actions as much as maintaining the body is amazing, and even more amazing are conscious actions which we control and are aware of and conscious actions which have no physical manifestation such as doing multiplication in our head. Even considering that our brain has billions of neurons and that there are all kinds of different neuron shapes which suggest specialization and that the neurons are organized into functional units seems that there must be more than the physical brain to explain higher functions. Many animals have better senses than we have, and the basic organization of their brains seems to be similar to ours. Few animals have larger brains than we do and yet they do not seem capable of higher functions. What is it besides the brain made up on neurons that transmit action potentials that is needed? What makes a brain a mind?

 

            We might make better sense of human behavior/experience by exploring more irregular situations like that of Christopher Reeves.   We cannot create these situations because that would be unethical, i.e. directly harming someone, but accidents do happen and we might learn from them.

 

Congwen Wang's picture

Inhibitions, pheromones, etc.

One of the most interesting notion in our class is the wide existence of inhibition in our nervous system. I've never thought about this matter before, and I find it actually quite important. Without a certain level of inhibition, we may experience extensive exposure to all kinds of stimuli and get exhausted by processing those useless stimuli. Besides, it is amazing that our bodies are designed - in fact, evolve - to be able to filter unnecessary outputs even before they enter the nervous system. We can't hear ultrasonic sound, so we won't be bothered by the constant air disturbance around us.

Another intriguing topic is the effect of pheromone. I wonder what the advantage of menstrual synchronicity is from an evolutional perspective. One hypothesis of this matter is that since polygamy was common in the past, the male individual might get confused if his female partners are in different phases of menstrual cycle. However, I can hardly agree with this hypothesis. I feel that different ovulation time can actually increase the chance producing more offspring, because menstrual synchrony will decrease the time for the male to mate with different female. Therefore, the evolutional value of menstrual synchrony may lie somewhere else. I think this might be relevant with the synchrony of male body temperature cycle and female menstrual cycle, but I need more evidence. I may use this as the topic of my next paper.


Also, a brilliant collection of brilliant photos of flowers under UV light: http://www.naturfotograf.com/UV_flowers_list.html#ASTERACX

Professor Grobstein, thank you for reminding me why I love plants so much!

 

Saba Ashraf's picture

Neurons/detection

            An interesting topic that we talked about during class dealt with proteins and that one cannot detect anything without having proteins that produce the permeability changes. Basically, we detect certain things in the world by seeing, hearing, smelling, or touching because we have proteins that produce the appropriate permeability changes. This brings up a point that humans cannot detect everything in the world because we do not have the necessary proteins and permeability changes.   It would be very interesting to learn more about some of the things the nervous system can’t detect because of the lack of proteins that change permeability.  There can be so much going on and taking place in a room that we would be never know about.  For example, it’s amusing to think about how a radio is capable of detecting the noises in the electromagnetic field, yet humans are completely unaware of them.   It is also quite remarkable that the nervous system is able to respond and deal with the enormous amount of information that it is able to detect. It is important to note that what a human is aware of is not the same as the information the nervous system is getting.  Also, the nervous system isn’t even able to detect everything that is going on around us, yet it is still being bombarded with bundles of information.   

Another interesting idea I was not that aware of was the fact that signals didn’t leave a cable. For some reason, I had always imagined one signal moving through various connected cables; however, signals end in the cables and do not exit it. This lead to the idea that our neurons were extremely advanced and somewhat like a computer. Despite getting about 1,000 signals, neurons are still able to make their own signals based on the numerous signals they receive.   

gloudon's picture

forgetting

 "From neuronal signals, we have learned that neurons are computers because they take in information, integrate and process the information and then passes on more information.  Therefore, the brain is made up of all these "computers" which dictate our behavior."  mchen

In response (in the form of further confusion) to michelle's, if neurons are computers, then what happens when we forget?  Is forgetting just a malfunction of a neuronal signal path?  If this is the case, are long term memories and short term memories in different computers because they are in different parts of the brain?  I guess this makes sense because head injuries can only impair a person's short term, or long term memory.  

If forgetting is the loss of a pathway, then do we get that pathway of neural signals back using the same computer or another computer? Is forgetting a product of a computer freeze? 

mcurrie's picture

Words and Memory

 Like everyone else I've been wondering about the other senses that we do not have and so cannot experience or senses that we have but are not aware of. I was thinking about how the senses that we are aware of can be manipulated. Like when you're a child or even when you're in the womb and you here your mother's voice and "know" that this is your mother since you can recognize the sound without being aware of it. Then as you grow you pick up new sounds, give them names, and those are what makes up of your experience. I read in a book that in order to have a memory of something you have to make a name for it or have a word that you can connect your feelings and other senses to, like what you saw and smelled and heard. By placing a name or word to an experience does that muddle with what you actually experienced. When you have a feeling that you can't describe and you keep trying to find words for it but can't. I guess you then just say it was a feeling and that is the word you connect many of your unknown experiences with. Although with so many different experiences being placed with one word your memory can definitely get very confusing or place two things together that are related but did not happen at the same time. I wonder if because when you're born and the first couple of years you haven't placed words with experiences yet or really understand words is why you don't have memories from those years and you have to rely on your parents for some details. We learn with words, seems to be a good summary. For example, a parent is cooking and their toddler is in the kitchen, in order to make sure they don't burn themselves the mother will say "hot" and show a gesture of pulling their hand away from the stove so the toddler understand the word hot and will make the same gesture and then understand that feeling. Then it's pain that makes it so the toddler doesn't continue to touch very hot stuff. It's interesting how much language and words are critical to our way to life in learning and communicating, etc. 

emily's picture

Memory, from "Proust Was a Neuroscientist"...a ramble

It is still hard for me to fully grasp how action potentials and synaptic potentials become our reality, our creative ideas, random thoughts, and feelings. I want to share an idea from the book I am reading (for the book review), Proust Was a Neuroscientist by Jonah Lehrer, about memory that relates to what we have learned about with respect to neuronal connections and may help put my question into context and maybe even help me (and others) clarify as I explain it out. 

Lehrer recounts a so-called controversial theory about how our memories endure even when we've forgotten about them, how memories last, from Dr. Kausik Si (former postdoc in lab of Nobel laureate Eric Kandel). Si realized "the mind is in a constant state of reincarnation" so, "our memories must be made of a very strong material, something sturdier even than our cells". But Si also realized that a neuronal memory also had to be specific. As we discussed in class, things like memories and ideas are patterns of activity across inputs or outputs (sensory or motor), so this makes sense in our context: a specific  is a specific pattern of activity. Si then thought about what would mark a specific dendrite branch as a memory, for a specific pattern. To sum up his experiments and thought processes with its conclusion, Si found a prion, a protein that can functionally exist in two states  (active and inactive) and can switch their own states, or, activate themselves. The prion Si found, CPEB, is able to change its shape with ease, "creating or erasing a memory", as neurotransmitters like serotonin and dopamine can change the structure of the protein into its active state. Activated CPEB marks a dendritic branch as a memory. From there, it can "recruit the requisite mRNA needed to maintain long-term remembrance" (mRNA --> protein, and memories need new proteins). Then, a reminder of that memory, like a smell or a taste triggers "a rush of new neurotransmitters to the neurons representing [that memory], and, if a certain tipping point is reached, the activated CPEB infects its neighboring dentrites. From this cellular shudder, the memory is born". Furthermore, because CPEB is a prion, "every time we conjure up our pasts, the branches of our recollections become malleable again. While the prions that mark our memories are virtually immortal, their dendritic details are always being altered...."

So, to conclude, again: memories are specific patterns of neuronal activity. When stimulated, that same neuronal pattern will fire, and become the memory from before in our heads. But, as we are always changing, influenced by our environment, we are always making new neuronal connections, new memories which feed off each other. Our memories are always different each time we recall them because we are always different when we recall them. Action potentials are all-or-nothing, neurons are isolated from each other, but the "empty" spaces between them, the synaptic clefts, allow for different patterns of activity. Our memories "exist as subtle shifts in the strength of synapses", but what about ideas and thoughts-- original, or are they also triggered by past experiences? Are ideas and thoughts merely spontaneous/random outputs from neurons triggering a pattern of neurons? How does this pattern know how to travel? If "random motion" (of ions) causes random outputs, how come our thoughts and ideas are so organized? Is "inhibition" a major key in organization?

mcchen's picture

From neuronal signals, we

From neuronal signals, we have learned that neurons are computers because they take in information, integrate and process the information and then passes on more information.  Therefore, the brain is made up of all these "computers" which dictate our behavior.  The term "computer" sounds very mechanical which makes me think that anyone with a mental disorder can be taken to a mechanic and be fixed immediately.  While we have learned the general basis of neuronal signals, I can't seem to tie it to behavior and the brain.  I feel that behaviors are subject to interpretation and everyone's brain interprets situations differently so how can we possibly have a reference point to start learning the connection between signals and behavior? We also discussed that more than half our synapses are inhibitory which leads me to believe that our "default" mode is to be expressing ourselves at all times.  So is it due to our inhibitory synapses, that we are able to contain our emotions or thoughts sometimes?  

aeraeber's picture

Depression is helpful?

Reading Lehrer’s article “Depression’s Upside,” my gut-level response to the idea that depression could be beneficial was horror and disbelief. I found it difficult to believe that such a feeling could ever help anyone. I certainly don’t find the urge to hurt myself in order to alleviate the paralyzing guilt over a silly mistake particularly helpful. I realized however, that Andrews and Thompson were talking about a different kind of depression, or at least a different level of it. What they really mean, in my opinion, is simple sadness that lasts a bit longer than a person would like. I agree that sadness can be helpful, that it forces you to reflect on your problems and find solutions for them. Depression, however, stops you from seeing those solutions on your own.  I can know, intellectually, that my friend will forgive me for the stupid thing I did or said, but I can’t forgive myself, because I don’t believe that they should forgive me.  Today is a good day, so I know can read my last sentence and see that it doesn’t make sense, but on a bad day, it is the most logical thing in the world.  Yes, real world problems can be a source of depression, and sometime therapy is just as, if not more, helpful than anti0depressant medication, but the need for therapy is still dysfunction.  Needing someone else to talk you through your problems so that you can see a solution that you would never find on your own, no matter how much “time to think” you had, is not an evolutionary advantage. Lack of functioning or even just diminished functioning would have gotten early humans killed.

The article also mentioned the link between creativity and depression and the idea that depression increases memory and some measures of intelligence. In regards the latter, I would argue that it applies more to sadness than to actual depression. A “low mood” might help you focus on a memory exercise, but, the researchers admit that this effect was only present when “the subjects were distracted from their pain.” I agree with Lehrer that the connection between creativity and depression has something to do with self-loathing. If you hate your writing or your painting or your music, you might continue to work on it, to try and make it into something you don’t hate quite so much.  You see the flaws in your own work more sharply than any other critic, because you cannot see anything you created as worthy.

To some degree, I understand where Andrews and Thompson got their idea; it goes along with the subject of this week’s forum.  Neuronal signals can’t explain all of human behavior, and what they offer is a possibly reasoning behind some neuronal signals.  Things in the brain have to happen for a reason, something has to cause neurons to fire. There has to be a reason why a signal follows one path instead of another. How did the brain get to be the way it is? How and why are some connections made and others not made? Where do the dysfunctions of the brain come from? Andrews and Thompson look to evolution for an answer, but maybe there are other places to look, or even other answers to be found in evolution.

 

sophie b.'s picture

 I thought this article was

 I thought this article was quite interesting to look at from an evolutionary perspective, to me it seemed as if the rumination cycles had a broader effect in this article aside from its link with creativity. The authors also suggest that this type of depression could possibly make an individual more adaptable to the world around them. They discussed this theory in a modern context of someone who suffers from depression after a divorce, learning to better understand social relationships as a result of rumative cycles. However this could apply to a number of contexts in which people who suffered from depression would learn from their mistakes (perceived or real) and as a result develop life skills- which seems as if it would be extremely beneficial in an evolutionary context. 

lfrontino's picture

Evolution at Work

 

Something that really struck me was how precisely tuned our bodies are. We discussed how our bodies only respond to the signals for which we have the proper proteins to bind to receptors. For some signals, like UV light, we do not have the proper proteins to pick up on them. I looked at pictures of some flowers under UV light, which have patterns that can be seen by bees, presumably leading the bees to pollinate these certain flowers. Humans don’t really have any need to see these patterns, since we don’t pollinate any flowers. It is clear by this example how much of a role evolution has in the abilities of our bodies and how the behaviors we exhibit are directly connected to our certain brain connections. 

It makes me wonder, what else is going on in the world that we aren’t aware of? As humans, we always consider ourselves to be the most aware and in charge of the animal kingdom, but it is probable that other animals are responding to certain stimuli that we have no idea even exist. Our sense of reality is so warped by our perception of the world, which is not even an accurate depiction. It reminds me of colors, and how different people may have different perceptions of ‘blue,’ but we would never know it, since we can’t see through their eyes. 

 

Jeanette Bates's picture

Other Senses

            What we have learned is how the brain creates action potentials and how those action potentials travel along a neuron and eventually produce a response. We’ve also learned how signals are transferred from one neuron to another. We still have a lot to explore, however. One thing that merits further exploration is what neurons (as in what type of sensory neurons) receive specific signals from the outside world. Personally, I would like to see how these receptors are a part of or contribute to the “other senses:” the senses beyond the five that we are familiar with. I think that I understand the “big five” senses well. We have optical receptors in our eyes, mechanical ones in our ears, and other specific receptors in our body that help us smell, taste, and feel. These I understand, but I don't quite yet understand how the other senses would work. For example, how does the “perception of hormones” sense work? I know that it must-since women’s periods sync and insect males can (seemingly) innately sense a female’s hormones, but I don’t quite understand how these signals are received. Is there something on the inside or the outside of the body that just picks the signals up? I guess this could happen, but it’s hard for me to conceptualize. What I’m wondering is the following: what makes us so sure that our ability to detect hormones is not somehow a part of one of the “big five” senses? We may be able to smell hormones, or to see the affects that they have on someone, without fully realizing that that’s what we are detecting.  I have read studies in which men had to choose pictures of women that they deemed the most attractive, and more often than not, these women were in the middle of their menstrual cycles. These men were nowhere near these women and could not pick up their hormone signals as a result; however, they still thought that the menstruating ones were more attractive. Rather than detecting hormones, they saw the affects of them and became aroused that way.

            I also wonder if our sense of smell might help us to detect hormones. Sometimes, when we are attracted to someone, they seem to “have a nice smell.” And even if we are not aware of the smell consciously, I don’t think that this would mean that it isn’t there. We aren’t aware of everything that touches us, for example. In fact, I think that if we were aware of all of it we would go crazy; however, I don't think that this means that the feeling isn’t there; there just isn’t an awareness of it. Therefore, I think that the sense of smell can detect hormones. I think that our ability to detect hormones is something that may be able to be explained by the five senses, or maybe a combination of the senses.  I’m not trying to say that a separate sense for hormones doesn’t have the possibility of existing, but I won't be convinced that it exists until we discover how humans and other animals pick up on hormone signaling. 

Lauren McD's picture

Filling the gap

I'm glad that we went into great detail about the inner-workings of neuron firings this week in class. We started off the course with more general thinking and now are delving into the science behind everything. It's absolutely miraculous how a simple 'battery' is responsible for all the functions of a human being. It is difficult sometimes to force oneself to associate the change in permeability of a membrane with a significantly complex output such as thinking. I think we still need to fill in all the empty space between the two, but I'm sure that's coming up in class soon. We have already discussed this difficult transition in previous blogs, acknowledging that it's near impossible to make the transition any easier. However, I am certainly curious about the information that will fill the gap. I've learned about neuron firings and I've learned about behavior in previous classes, but I never truly had a course in which I learned the processes between the two. I suppose it's like a vast network, but how does a simple electrical/chemical signal get processed into running, reading, or eating? This is what I am most interested in learning about: how a neuron firing becomes a behavior. I assume the next step is discussing propagation along neurons, although we did touch upon synapses and their functions in class. While these topics will greatly help our understanding of all human behavior and experience, in response to the prompt, we never can make sense of all human behavior and experience. Sure there are patterns and associations, but there will always be exceptions to the rule unless we make up enough rules for every possibility. This is a discouraging goal, but the necessary information to fill in the gap between neuron firings and behavior will greatly help us as students understand human experiences to a greater extent.

Schmeltz's picture

It makes me question the

It makes me question the "stuff" of the self -- how can we have any sense of self awareness if we are not aware of most of the ongoing functions of the nervous system?  And at the same time, how can we function in any other way but with ignorance to this thorny reality?  If we embrace the uncomfortable notion that we are mostly products of our unconsciously- functioning nervous system, what happens to our individuality, our sense of self, our ability to understand -- or begin or pretend to understand ourselves -- so that we might understand others?  ... egleichman

This notion of the self being completely constructed by the nervous system initially seemed uncomfortable to me as well until I got to thinking about it.  I mean, think about if we actually had complete control over our own nervous systems.  Imagine that we could start and stop each and every neuron in our body at our own command.  Well, how would that work?  How good of multi-taskers could we really be?  Would we ever get anywhere?  Imagine if we were in control of the nervous system rather than the system being in control of "us".  I think this would just be painfully overwhelming.  As it is, with my nervous system being in control of me, I still become overwhelmed when in the presence of too much exciting stimuli.  I cannot imagine how it would work if I were consciously determining the entire series of responses.  I wouldn't know where to start or stop.  A simple response would take so much effort because you would have to think about it - you would have to go through each neuronal step, generate each action potential, to engender a movement or response that the nervous system can generate in a matter of seconds.  I think it is fortunate that we do not possess complete control and I think it is fortunate that we are mostly products of our unconsciously functioning nervous systems.  What a excruciating time we would have if it were all conscious functioning.  However, I do not think I would go as far as to say that we are merely products of an unconsciously functioning nervous system. I would like to think that somewhere in this nervous system there is adequate room for self (if not an actual self than at least a sense of one), individuality, and the ability to understand ourselves a little more.  I think it is liberating that I do not know what is going on all the time with me and with my surroundings.  I'm a little too overstimulated as it is.  I think it is freeing to think that I am not responsible for all my feelings, my bad days, my irritation, my unawareness, my lack of understanding of my self, or even for my self.  I like that there is "stuff" of the self that may be beyond my grasp, yet I also like to think that some "stuff" of my self is able to be controlled and/or understood.  I think it's a beautiful balance.  I do not think our sense of self has to be jeopardized in light of a "unconsciously functioning nervous system".