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Neurobiology and Behavior, Week 6
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, what further insights into both the nervous system and behavior come from understanding action potentials, receptor and generator potentials, and synaptic potentials? Does an understanding of the nervous system at the cellular level make it seem more or less possible that brain = behavior?
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A Random Walk
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neurons as a computer network?
Unfelt Cues (of the nervous system)
This week's discussion in class was the most fascinating one we've had so far. The idea that our Nervous system knows a lot of things we (our I function) are not aware of both intrigued and made a lot of sense to me.
A lot of us decide whether or not we like a person within the first few minutes of meeting them (or at least whether or not we want to continue a conversation with them). I am wondering if this is a combination of our nervous system's input (the other person's pupil is not dilated enough), or if it is our own decision that we dislike them (for whatever outward manifestations of their character). Or is it that even when we think it is our decision, it actually comes from our nervous system. This is interesting, for if we go Emily Dickinson's way, and the world is a construction of the mind, then isnt all of our minds hiding a parts of the world from us? (Sensory cues the nervous system picks up, beyond the five senses we are accustomed to).
I also read some interesting articles regarding menstrual cycle and pheromones. (That I can't find the link to now). It said that researchers who carried out a study in a nightclub/bar found that lesser men approached women who were menstruating. Evolutionarily this makes sense because women can't typically 'mate' when they are menstruating. Also, pheromones released by women when they were ovulating made them seem more attractive to the opposite sex. I was wondering what the exact evolutionary explanation for co-ordinated menstrual cycles are. I also find the idea of the alpha woman put forth earlier in this forum extremely interesting, and I wonder if the alpha women in our cultures are the one that are socially more popular.
It is interesting to think
Willpower - Action without Awareness
Our discussion concerning action potentials compels me to ask a potentially crude question.
Are action potentials reaching threshold directly responsible for not only compulsions, but difficult, reasoned decisions?
Take the following mundane occurence:
I am lying under the covers on an extremely cold night when suddenly I realize I left the front door unlocked. Now I am snug in bed, in a considerably comfortable position. What must ensue is a struggle between the urge to remain warm and comfortable and the "thought" or rational realization that leaving the door unlocked might very well facilitate an invasion of my home. Eventually, I do throw myself out of bed, but the process is perhaps analogous to a pressure system, wherein my urge to stay warm is gradually overcome by my fear of danger (or desire to remain safe).
Is this example entirely predicated upon action potentials? was my getting out of bed the result of a self-generated inter-neuron action potential reaching threshold? Or is a thought itself a successful (past threshold) action potential?
Also note that I claim a compulsion (an urge) is coming into conflict with a rational thought, but I wonder if there is any sort of dichotomy when it comes to imperative thought or action. That is, the "decision" to lock my door can only manifest itself toward action as an urge with an emotional basis. A rational thought cannot compel me to jump out of bed and sacrifice my comfort; what started off as an indifferent logical realization came to influence my actions as fear/desire.
What I am trying to get at, is the nature of willpower. The above conflict between staying in bed and getting up seems illustrative of something significant. Action is an outpout; it requires motor-neurons to fire successfully. However, in the moment where a decision becomes an action, what we have is a thought bearing upon us as compulsion. What signals then, what action potentials, are operating when I finally will myself out of bed? I can imagine there is an integral dynamic to grasp in this moment, wherein thought becomes compulsion and overpowers a competing compulsion.
One thing i see hear here is that the I-function cannot manifest in a moment of action. If every action comes to bear as compulsion, then self-awareness loses salience in that moment. It was after all an emotional fear/desire that propelled me out of bed, not a logical series of thoughts.
Does this not seem an imperative matter to understand? Any claim to morality or responsibility needs to address the inescapable absence of awareness in the discreet moments wherein a thought becomes compulsion becomes action.
connected
not so different
shared identity
In a similar vein, I think it’s important to be aware of how small genetic differences can have huge impacts on anatomy, physiology, and more abstractly, behavior. Humans are currently thought to share approximately 94% of the same genes as chimpanzees. Clearly that 6% difference makes a huge impact. Seeing as humans are more similar to one another than to chimpanzees, we must share an even larger amount of the same DNA within our species. When thinking about medication, doctors should therefore be able to predict the relative effectiveness of treatments and medications. Of course, differences are seen with some people. For example, some medications warn that after taking the pills the person may experience headache, nausea, upset stomach, etc. Obviously these side effects do not occur in all people nor do they occur at the same level of severity.
DSM classifications also leave some room for classification. In schizophrenia, for example, patients exhibit a variety of symptoms—some have delusions while others experience hallucinations. However, their similarity in other behaviors leads to the diagnosis of schizophrenia. Thus while we like to think of ourselves as individuals who are unlike any other person, we must also remember that our genetic similarities are what keep ultimately unite us.
Receptors that don't go to the "I" function
Receptors for Anything?...and their implications
As we were discussing potentials this week, in particular action potentials, I was particularly interested in the many different receptors that our nervous system maintains to detect stimuli (e.g. light, temperature, gravity, etc.) and convert them into an electrochemical potential. Further, I thought it was interesting that our nervous system may 'know' more stimuli than we are consciously aware of.
Albeit awesome, in the most literal sense, the nervous system has limits, or so I gleaned from the discussion: our model of sensory reception seems to say that we can detect all stimuli for which we have receptors (proteins) that are made that detect those stimuli. This circular construction reminds me of the adage of medical microbiology who insist that antibiotics kill only the bacteria that they can kill, and not new strains that evolve resistance to the antibiotics. In this vein, I am curious about a few things of sensory reception:
1. Could we, humans, in theory, have all of the receptor for 'all' stimuli. Since we perceive and 'create' our world in our 'mind's eye', is this not a reasonable proposition? If so, could the fact that some people are more sensitive , in a broad sense, not just an emotional one, than others be a product not of their bodies maintaining a wider array of receptors, but that the same receptors they have and others have just may be activated by different thresholds of stimulus? For whatever reason, could it be that the individual differences in perception are only a product of our different thresholds of sensation? I vaguely remember reading about the psychology of pain, and how a current model posits this idea of thresholds to explain why different people perceive pain differently.
2. I'm a sap for evolution, so here goes my evolutionary tangent to all of this. Assuming that the threshold model is void, or largely 'more wrong' than other models, and that differences in perception between individuals, and species, are due more to differences in the acquisition of different receptors, then I am curious as to how more standard models of phylogeny (i.e. 16S, or 18S) compare to those that measure the occurence of certain receptors (i.e. cannabinoid, opioid) in some species rather than others. Does it put birds closer to us than other mammals, for instance?
3. Also, could the different 'doors of perception' to quote William Blake be a source of madness (e.g. schizophrenia)? Could it be that those who many would perceive as 'abnormal' or outliers because they 'feel' and 'sense' things that others do not are in fact just suffering from having different receptors than others? Could it be that some schizophrenic patients do in fact sense things that others do not? There's no conclusive way to tell, at least not one that i can think of. If this were deemed 'true' in some sense, wouldn't this align more closely with the Ancient Greeks' notion of madness as something divine and well-respected because they believed that one who was 'touched' (e.g. Oracle at Delphi) could give insight to the rest of us that we couldn't figure out for ourselves.
OR, could it be that those 'mad' individuals are just more evolutionarily 'advanced' than the rest of us. In a certain sense, could they be smarter because they sense things most do not. Certainly that's a thought i think some believe after hearing of accounts of madness like John Nash's.
4. Also, why stop at sensory receptors that we know about. Could there be receptors for a certain kind of logic, intuition, or intellect? Just a thought.
Week 6
taste receptors, propiosensors, and intuition oh my!
I'm starting to think that for the most part, brain = behavior. Activity in the smallest boxes (the neurons) affect the bigger boxes and overall affect our behavior. Receptors in our bodies allow us to process information from the environment and then allow the brain to respond accordingly (or ignore the inputs overall from time to time). However it's interesting to see how our reality is limited. Sure we can see, touch, smell, taste, and hear but we lack receptors to sense gravity and magnetic fields. People mentioned stories of animals who have a sense of knowing when people are about to die; I've heard that animals in the wild are more in tune with nature than we are so they can predict when the weather is going to turn into chaos. It makes me wonder what else we are missing out on; what else is going on in the world that we are not completely aware of? Is it possible to find a satisfactory answer?
The idea of multiple receptors from intuition to propiosensors is pretty fascinating. Propiosensors make sense but where is the box for intuition? Where are the intuition receptors? Do neurons process information from intuition receptors in the same way as they do from other receptors?
Cultural interpretation and physiological changes
Overriding Sensory Input
subconsciousness
It was interesting talking about our senses that we don’t recognize in daily life. Just like a submerged part of an iceberg, subconsciousness plays a large role in sensing and determining the human behavior. In my daily experience, I found it interesting that when I don’t wear glasses or contact lenses, I am so easygoing and when my vision is clear, I tend to get nervous more. So, depending on the vision, my behavior changes. I guess my clear vision suppresses my subconscious activity of the brain and raising the level of consciousenss and reason. I want to know if there is scientific evidence or observation about the relationship between human eye’s vision, brain, and behavior.
Reading previous posts above, I liked the discussion in which our brain uses selective attention to focus on certain stimuli. I wonder what leads our subconsciousness to pick certain stimuli. Is it previous experience or genetics or random? What would be the mechanism of picking out some of the many stimuli?
My second question is why would the brain constantly process input? Why would the human brain want to satiate itself with stimuli? Is it about maintaining certain chemical homeostasis—a scientific phenomenon of human’s instict of knowledge generation?
Coordinating Menstrual Cycles: Does Alpha Female Rule All?
We were discussing in class the different receptors that may be sensitive to and effected by external factors in our environment. Among these were the possibility of women's menstrual cycles aligning with each other due to receptors that women may have. In this argument, if there are gender specific receptors such as these, then the case could be made that brain = behavior. However, how are we viewing brain = behavior because biological behavior and social behavior are different.
The fact that there are hidden receptors that do not pass through our I-function would provide a reasonable explanantion for how one woman has a different menstrual experience from another and why one woman is biologically labeled as the alpha-female and makes other females regulate onto her menstrual cycle. Are there any commonalities in alpha females socially and biologically in terms of their menstrual cycles and the receptors that their bodies encapsulate? Do the women that exude alpha-female behavior in the social world also have the propensity of regulating their fellow women onto their cycle?
chance
In class we talked about our conscious actions (the actions that go through the I-function) and our unconscious actions (actions that our NS is aware of but we are not). The examples were unexpected, we discovered another piece of ‘common knowledge’ that we take for granted every day (for example that we have 5 senses) without really thinking about what lies behind these assumptions. These realizations make me wonder about our explanations of ‘unconscious’ actions or senses beyond the five conscious ones we experience. Some people belief in paranormal phenomena while others say it’s all random or by chance. I’m interested in the I-function, in the knowledge that our NS is aware of but we are not, and how much of it is just random or by chance.
Let's Not Forget About Glial Cells
In our continuing discussions on action potentials, synapses, neurons, and the senses I wonder why glial cells seemed to have been overlooked. I realize that there isn't much literature out there concerning these cells especially since neurons have been getting most of the attention. Whenever someone mentions "brain cells", he or she is most likely refering to neurons, the cells responsible for the hard wiring of the brain by sending and receiving both chemical (neurotransmitters) and electrical information. But I read in my research for the first web paper that neurons only account for approximately 10 percent of the brain. The other 90 percent is made up of glial cells. Is this alarming (ok, surprising to me) proportion indicative of some underlying concept of the glia-neuron relationship?
In my research about neuroplasticity, it was revealed that some glial cells perform some of the same functions that neurons were thought to be solely responsible for: emitting and receiving neurotransmitters. To further research on glial cells I stumbled upon an article (link provided below) describing a study by Rockefeller University on C. elegans that suggests the glial cell's importance to sensory reception. The study concerned the amphid, an organ in the C. elegan's nervous system that contains both glia and neurons. The organ contains 12 neurons 4 of which are completely surrounded by glial cells while 8 are partially surrounded with sensory endings exposed. To test the importance of glia to the neurons, the scientists removed the glia and observed the resulting shape of the neurons, the neuron's ability to respond to odors and temperatures, and the neuron's ability to absorb certain dyes. In the absence of glia, the neurons that were once completely surrounded shrivelled but the neurons that were once partially surrounded maintained their shape. However, these 8 neurons responsible for receiving stimuli from the environment were rendered useless. The C. elegans displayed trouble in finding their ideal temperature by crawling towards higher and higher teperatures. Their sense of smell was also affected by showing no preference or aversion to particular odors. From a molecular standpoint, the researchers focused on FIG-1, a protein secreted by only glia surrounding the amphid sensory organ. Without this protein, the neurons of the sensory organ had trouble processing external stimuli. Since FIG-1 in C. elegans resembles thrombospondin, the protein secreted by glia in vertabrates, the researchers suggest that the glia-neuron relationships observed in C. elegans may elucidate glia-neuron relationships in humans.
Without Glial Cells, Animals Lose Their Senses
behavior or chemical reactions?
I remember when i took an introductory psychology course in high school, my teacher taught me that behavior was just a bunch of chemical reactions colliding. It seemed as if the brain was recognizing many strange chemical reactions occuring inside of my body, and it ordered its own chemical reactions to calm or eradicate the unknown reactions and regain homeostasis.
Can someone consider behavior a form of reaction to maintain homeostasis? I mean, for example, when we're sad, we cry and it is said that a good bout of tears can help you feel better. So is that what we have emotions for? to maintain our body's balance but in an external rather than internal move?
Beyond the 5th Sense
The way our bodies can take information from the outside world and produce signals in the nervous system helps to understand more about the way our bodies work in conjunction with the I-function. The way action potentials, receptor potentials, etc. all require this idea of membrane permeability is so intriguing. Although what the membrane is permeable to may change depending on situation, the way the basic idea occurs in all the different areas is nice.
The post 5th sense channels we posses that do not channel through the I-function are the most interesting to me. The idea that many things occur that we are not aware of wasn't exactly new to me (e.g. Halo Effect) but now that I am starting to understand why this happens, makes the idea even more interesting and believable, they are slowly being moved out of the unexplainable category and into the accepted.
Thursday's discussion on
Thursday's discussion on extra-sensory perceptions, specifically pheromones, led me to think about what other examples occur in daily life. One question I have is whether danger is at least partially an extra-sensory perception. Let's take an infant or very young child for example who typically responds to fear by crying. Some infants may cry when any stranger enters the room, but others only cry when the person appears particularly "scary," the sort that might even instill trepidation in an adult. Is this fear socialized? Has the child, at such a young age, been trained to recognized certain aspects of one's appearance/body language as dangerous? Or is there something else allowing the infant to sense danger? Do dangerous individuals emit some sort of pheromone? In general, I guess I'm wondering whether individual's determination of a situation as dangerous is due more to extra-sensory perceptions or socialization. Is the "gut" feeling that people get due to such perceptions?
I also wonder if people, like animals, can smell fear. Dogs, for example, are often said to be able to sense fear in humans, and this supposedly explains why they will bark/lurch at people who are scared of them. I wonder if this capacity to detect fear helps a predator find prey and then attack that prey.
Finally, what are other extra-sensory perceptions and how are they connected to our unconscious?
Blindsight
Thursday's discussion made me think of an article I recently read in the New York Times on the phenomena of "blindsight." Researchers have found that it is possible for someone we would consider blind, someone whose visual lobes were entirely destroyed, to navigate a cluttered hallway and recognize some facial expressions. The article states that this phenomena of blindsight comes from a second unconscious visual system located in a different part of the brain from the visual lobes.
When I first read this article, I didn't really believe it, but Thursday's discussion on sensory receptors has not only helped me understand the article, but convinced me blindsight exists. Before class, I thought the only types of sensory receptors that existed were the basic five senses and as a result I couldn't really understand the article. In class we talked about how there are many sensory receptors beyond the five senses and that some of them are unconscious. Now I understand blindsight as one of these unconscious senses we discussed in class.
http://www.nytimes.com/2008/12/23/health/23blin.html?n=Top/Reference/Times%20Topics/People/C/Carey,%20Benedict
1. The idea that neurons in
1. The idea that neurons in the brain receive many moreinhibitory signals than excitatory signals is very interesting if you think ofthe energetics of the process. The human body is designed to be efficient. Ourcells each have specialized functions, each protein has a specific job, and ourbody is designed to run smoothly and without much waste. It seems that thehuman body is wasting a lot of resources by requiring so many inhibitorysignals in the nervous system. Is an excitatory signal stronger than aninhibitory signal?
2. Could inputs produce inhibitory signals? I think thatthis process is possible because of my experience with distraction. I may bedaydreaming in class and suddenly be startled from my thoughts by a persondropping a book on the ground. In this scenario, my thoughts have been stoppedby an output from my environment. Does this mean that the sound of the bookdropping on the floor produced inhibitory signals that halted the actionpotentials produced by my thinking? Or does the book dropping produceexcitatory signals that are able to “overpower” the signals produced by mythoughts? I don’t think that an input has to be all inhibitory or allexcitatory. The noise of the book dropping may produce inhibitory signals thattravel to the box in my brain that is controlling my thoughts, while otherreceptors in my ears pick up excitatory signals that travel to another box inmy nervous system that makes me turn my head towards the sound. Without boththe excitatory and inhibitory signals, I would never be able to react to theoutside world because there would by no way to turn off the action potentialsthat started without an input. I think that most excitatory signals come frominside the nervous system. Our nervous system is constantly producing actionpotentials that are interrupted by action potentials that are produced frominputs.
I'm interested in your
I know your brain uses
I know your brain uses selective attention to focus on certain stimuli. There have been studies that localized this selective attention ability to a certain part of the brain by looking at brain lesions in patients who lacked selective attention. I don't really know how your brain selects what to give attention to, but your current thoughts and interests probably drive your brain to focus on only what you want to or need to focus on. Thus, I don't think your brain sorts through all the information that it is given in a certain environment. I think a lot of the information may be unconsciously picked up, but the brain can quickly scan over and pick out what it will focus on and actually process.
This also suggests that there is a mechanism for inhibition in the brain since the brain is not processing all the information it receives. There are a lot of cognitive processes that require inhibition, such as being bilingual. People who speak two languages have to inhibit one language while using the other. I am debating between whether inhibition is a consciousness effort or if it happens unconciously. I guess it depends on what you are inhibiting. You could consciously inhibit certain behaviors, but you also unconsciously inhibit the external stimuli you are picking up but are not necessarily aware of. The question of what inhibition actually is in terms of brain chemical behavior remains. Does inhibition simply involve the ending of the propogation of excitatory signals or does it send separate inhibitory signal that releases chemicals that undo the work of excitatory signals, resulting in no output?
pathways
intuition of another's presence
I think you propose a very
(sub)conscious
We've been talking a lot about how the subconscious (the part of the nervous system that is not a part of the I-function) influences behavior and I was wondering if we could continue exploring this side of the nervous system. Is this how hypnotism works? Simply tapping into the parts of the brain that we are not always fully conscious of? What about dreaming? Is this where abstract ideas come from? What is the full relationship between the conscious and unconscious parts of the mind?
Is the I-function the only part of the mind that makes up our conscious selves? What other parts of the brain help us take in input and think about it? What other parts of our conscious sselves shape our behavior?
It makes a lot more sense
It makes a lot more sense to me how inputs can feasibly have no out puts -- as soon as we learned about the workings of the synaptic potential, it made sense. Understanding that there are just as many inhibitory areas as excitatory areas definitely let me see the world of input/outputs clearer. There could be a trillion inputs with no output, because there is the inability to sometimes continue the action potentials.
Looking at it this way, it makes me think that a lot more of my behavior comes from innerworkings of my brain, rather than my environment. The impact of creating sensations within the nervous system seems to weigh a lot more, now.
My Pony Told Me…
Last year, my pony told me that she didn’t want to compete at horse shows anymore. She was extremely burnt out, physically and mentally. She was asking for a long break from the strenuous schedule of chasing year end points.
There are a variety of reasons why I might choose to justify my decision to limit my mare’s competition schedule this year. It could be a case of projecting my feelings about competition onto neutral substrate. Or maybe anthropomorphizing my pony and her behavior.
Our discussion in Thursday’s class allowed me to add another option to the list. The idea that my intuition about my pony is informed by the sensory input I receive from her. This information is processed by my unconscious and crafted into a story that the I-function receives. This explains how I can know something without knowing how. Her behavior creates the sensory input that I receive from her and the way she behaves is a reflection of her mental state. So I can interpret something about her mental state. Maybe my pony was communicating with me.
For a similar story about a different observation see:
/sci_cult/bridges/matspirit.html
Misconceptions
I think it is important to