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week 5 - Neurobiology and Behavior

Paul Grobstein's picture

And so we have action potentials, spontaneous and otherwise, and synaptic potentials, excitatory and inhibitory. Thoughts about those and what we can/can't do with them? Or anything else on your mind this week ....

Serendip Visitor's picture


Retyping lost comment...
I am unsure if comment was posted it disappeared and comment field reset..
so here I am starting again
I have a question on sensory shutdown which is momentary.
I experience this frequently and it appears to be governed by stress and a decreasing tolerance to stress. The eyes snap closed and although episodes appear to be only 1-2 seconds in length it appears as a total loss of consciouness and mental images totally unrelated to surrounds are recalled momentarily. These appear quite spiritual in nature and are random.

This appears to be associated with a type of fatigue eeven though adequate sleep has been had. Emotional stress can increase the impact of this in a 24 hour period. Greater period of rest appear to alleviate. Tension and anxiety although controlled it appears that episodes can result from a panic like state where inadqueacy in coping with tasks at hand or lack of knowledge appear to stimulate.

No medical help appears available. It appears some medication, diet or behavior changes may be required to get to bottom of.

The symptoms appear to be like the brain is trying to protect the eyes as it is associated with looking at a computer screen. This has been a long term issue. Other syptoms may help to get to bottom of.

The actions are totally involuntary and there is no or limited control of them occuring. Also they appear to occur in a cyclic pattern as periods without can be experienced in a day.

JaymElaine's picture

The Sixth Sense

 So today, 02/20/07, we talked a little bit about the sixth sense in our forum discussion.  According to this discussion, we (our bodies) are constantly receiving information that we are unaware of, and the sixth sense is us being able to tap into this information on a conscious level. My question is, how are we able to receive some bit of information and translate it into a thought/notion that has been thought of by the "gifted". What signal, frequency, etc. are we able to perceive consciously and able to turn into a thought about a future event or knowing one's favorite animal? And, how are we able to do this? I understand that the answers are not out there for why/how this phenomen occurs. Many may argue that the gifted/psychics can hear voices (angels or spirits of some sort, or even God himself) while others believe that psychics are able to talk to the dead. In this case, where do we draw the line between the gifted and those who are experiencing psychotic episodes? Hmm, I wonder.

Jayme E. Hopkins, '08

Kate Sheridan's picture

Different Neurotransmitters, Same Action Potential?

I was thinking a lot about neurons and action potentials, and how there must be more going on in neurons than just the propogation of action potentials leading to the eventual release of neurotransmitters. Here's my thinking: in order to generate an action potential in a neuron, you need to depolarize (make the inside of the cell more positive) it. An action potential is only generated if you break through a certain threshold potential of that cell. After you break this threshold, you create an action potential no matter what, and you get the same response every time even if you continue to increase the amount you deploarize the cell. My question is this: if a neuron has the ability to release more than one kind of neurotransmitter, what signal determines what kind of neurotransmitter is released? The only signaling device I've learned about is the action potential, but clearly the neuron must be getting other kinds of signals to tell it what kind of message to spread across the synapse to the next neuron. Does anyone know what other signals neurons receive/transmit?

Kristin Jenkins's picture

Just off the top of my head,

Just off the top of my head, I dont think there is a different kind of action potential....I think the kind of message the neurons send depends on what neurons the action potential passes through. Neurons are like letters in the alphabet: depending on which ones you use, you can spell a whole dictionary of words of words. Imagine the endless possibilities of messages you can send with all of those neurons in your body....

dmckeever's picture

Ok- But even that does not


But even that does not explain how a neuron determines which neurotransmitter to release (which in turn, determines the message being spread across the synapse). I think Kate is asking how, after depolarization, is the signal that (let's just say) invokes movement in my finger out of pain differentiated from a signal that invokes movement in that same finger as a conscious gesture? If all action potentials are the same and if the motorneuron in my finger for finger movement are the same, then where is this signal encoded? And, I think she was hinting at neurotransmitters: that which transmitter is released dictates the output, but what dictates that neurotransmitter's release? And though I think what you've said is important, the question arises: then how is it determined which neurons it passes through? I am not saying that I have the answer, or that we are expected to, and though I think what you've said is part of it, it isn't all of it. I considered that maybe certain neurons were coded for certain signals, and that level of organization would not surprise me, but I thought the uniquness of the brain lay in the structural changes that can be made, rather than the variety of neurons. I guess my biggest question is, after an input (say, I touch a hot stove), and action potential is propagated, and how does it know what the input was right from the get-go? How is what happens next determined? Let's start with the beginning. 

eshuster's picture

Does this website advocate internet Addiction

If one looks at the web forum for this Neurobiology and Behavior class, it is evident that fifty something students log onto the same website to discuss many different issues. They log on at least once a week to read what others have written and respond to their writing or write about a topic that has interested them throughout the week. This is a prime example of socialization on the web. There are so many forums that enable people to post, comment, and discuss issues that appeal to their needs and desires. These forum’s are like diaries but the person is not talking to the diary but to another individual who can comment and suggest changes or another way of thinking of the same situation. These online forums are like group therapy only they are free and they enable people with different backgrounds and different lifestyles to comment and enlighten the writer of the initial comment. We are addicted to communicating our problems with anonymity and without judgment.


Internet addictions are behavioral addictions that currently are being reevaluated. Researchers are moving toward a definition of addiction based more on behavior as they think about whether brain activity and biochemistry are affected the same way in behavioral addictions than in drug addictions (7).  According to Dr. Howard Shaffer, who leads the Division on Addictions at Harvard University, addictions are based on experience. They are repetitive, high emotion and frequent. It has been found that neuroadaptation, changes in neural circuitry that help perpetuate behavior, occur in behavioral addiction (7). The field of psychology is currently attempting to narrow down the controversial argument this topic has begun about behavioral addiction versus drug addiction. In behavioral addictions, the same brain activity in the frontal and limbic regions can be observed as that of cocaine addict when exposed to their respective stimuli as seen on functional magnetic resonance imaging (fMRI).

Molly Tamulevich's picture

Holy holography!

I am writing my web paper on the holographic theory of the brain, and as I read these posts on phantom limbs I can't help but relate it to the Holographic model. Basically, in a holographic model of the universe, which is more in the realm of physics than biology, the universe is full of waves which are interpreted by our senses into visible, smellable, hearable things. These waves bounce off of and mix with each other and create interference patterns. A hologram is produced by the interference patterns of light waves reflecting off of an image. One of the distinctive qualities of a hologram is that every bit of the hologram contains an image of the whole, so if you cut a tiny piece of holographic film off of the original, you will be able to see what the original image was in its entirety. According to the model, memories are dispersed across the brain in this way, as are some learned behaviors. I wonder if phantom limb pain can be explained by saying that the memory of that limb is still in existence throughout the brain, that the waves that made up the limb are somehow still imprinted in the person and therefore reacting to the external environment.

LS's picture

Outputs --> Inputs

I wrote my paper on aphasia, a language disorder caused by the brain.  Individuals with aphasia have trouble with verbal and written language sometimes being unable to understand other or make understandable sentences and statements themselves.  One type of aphasia occurs in the Wernicke's area in the temporal lobe.  In Wernicke's aphasia individuals can form fluent sentences however they do not make sense and they sometimes use neologisms, or made up words.  Because these individuals cannot understand what other people are saying to them they do not understand that they are talking in gibberish and making up sentences that are unclear.  I think that this may be similar to the afferent loop.  These individuals create an output but because there is no input (they do not understand verb language) they never realize what they are saying.

LS's picture

Outputs --> Inputs

I wrote my paper on aphasia, a language disorder caused by the brain.  Individuals with aphasia have trouble with verbal and written language sometimes being unable to understand other or make understandable sentences and statements themselves.  One type of aphasia occurs in the Wernicke's area in the temporal lobe.  In Wernicke's aphasia individuals can form fluent sentences however they do not make sense and they sometimes use neologisms, or made up words.  Because these individuals cannot understand what other people are saying to them they do not understand that they are talking in gibberish and making up sentences that are unclear.  I think that this may be similar to the afferent loop.  These individuals create an output but because there is no input (they do not understand verb language) they never realize what they are saying.

AriannahM's picture

Malfunctioning Action Potentials = Mental Illness?

If all of our thoughts and actions are generated by action potentials and synapses firing away, are all mental illnesses malfunctions of action potentials? I wrote my web paper about the prenatal causes of schizophrenia and it really got me thinking about this. Many research studies have implicated prenatal and birth complications as the causes of schizophrenia. Schizophrenia doesn’t develop until early adulthood (late teenage years to late twenties). Usually those who are affected by schizophrenia lead normal lives until their symptoms start. If schizophrenia is a mental illness (which it is) and mental functioning is controlled by firing action potentials, then why can the actions potentials work properly for twenty years before “malfunctioning”?

Rebecca Pisciotta's picture

It is true that all of our

It is true that all of our thoughts and actions are the result of patterns of action potentials. But the electrical action potentials themselveself are not the only occurance responsible for brain function. We must recognize the structural, chemical, biological, environmental, and genetic involvement as well. I have never actually heard of action potentials malfunctioning. I can imagine it would look something like a generated action potential spontaneously ending en route down an axon, or failing to be initiated by a sufficent stimulus. Physiologically I do not know if this could happen, it would require something to be fatally wrong with the cell, or the extracellular environment.

While action potentials malfunctioning may not be a likely cause, the signals which tell the action potentials to occur (or not) are. Neurotransmitters are released from one neuron into the synaptic cleft and received by another. The "correct" transmission of a signal is reliant on the correct neurtransmitter being released, it being released in the right concentration, staying in the synaptic cleft for a certain period of time, and interacting in a specific way with the right receptors. These "normal" functioning of these steps can be affected by genetics/environment/and biology.

Alot of work on schizophrenia has been done through utilizing antipsychotic drugs, and using what we know of their mechanism of action to deduce the possible mechanism of action of the disease. It seems likely that schizophrenia is at least partly caused by a malfunction in the signalling pathway of dopamine. Drugs that block the D2 dopamine receptor aleviate some of the symptoms of schizophrenia. Schizophrenics might be releasing too much dopamine into the synaptic cleft, not reabsorbing it (so that it stays there longer), or have more than the normal amount of receptors for it. The function of D2 is inhibitory, it decreases the likelyhood of an action potential in the post synaptic cell. The over activation of D2 receptors in schizophrenics will directly effect the number, frequency, and patterns of action potentials in the brain. And therefore directly effect behavior, as is seen.

So it is true that in the end the disordered behavior is caused by an alteration of the action potentials. But the malfunction occurs not in the action potentials themselves, but in the means by which they are induced.

While this does not explain the timing of the onset of symptoms if I had to hypothesize, I would say that the environmental influences that occur during childhood, and the environmental stresses that are often exacerbated in adolesence could be responsible for the later onset of symptoms

Lauren Poon's picture


Many people have a habit of gesticulating when talking. Some people do it too much while others are more subtle. To a viewer, constant hand waving while talking may seem distracting. To the speaker, however, they may never notice. We learned that the hand waving is an output that triggers in input of the person seeing their hands move. When people are habituated to moving their hands, their vision may change but they are still unaware of the motions. Does the eye habituate to the hand motions? A series of hand motions are never the same so the eye does constantly receive a change in output. Maybe, the brain is used to not the physical movements but the pattern of activity necessary to move the arms. I’m not sure. How does the brain habituate itself to a habit?

francescamarangell's picture

Visual Learners

In class on Thursday we discussed the reafferent loop of the nervous system, where an input causes an output, then this new output triggers and a new input and so on. For example it is easier to walk forwards rather than backwards in part due to the fact that you can see where you are going. As you step, your brain visually registers what just happened and where your limbs are. You are able keep stepping and keep moving with ease thanks to visual confirmation and the reafferent loop. In class we discussed the reafferent loop with respect to the physical control of over our bodies, such as lifting a leg or moving an arm. I am interested in how the reafferent loop affects internal processes of the brain like learning. Can the reafferent loop explain why some people are visual learners? If a mathematical concept is sketched out in a diagram and then explained to me, I am much more likely to understand the problem then if the professor merely reads it out loud. The diagram offers a visual confirmation of what I am learning. Is this the same as watching your leg move or seeing the angle of your arm to confirm where it is in space?

katherine's picture

Autism and music

I was doing some reading on my research paper about autism and in light of last week’s discussion about outputs creating further inputs, I thought that this condition was particularly interesting.  Autistic individuals often have sensory integration difficulties meaning that they are hypersensitive to normal stimulation.  For example, they have little or no pain sensitivity or experience discomfort when they hear certain noises that others would consider normal. 

Interestingly, music therapy has been a successful method to calm autistic children and teach them proper ways to behave.  One specific method involves the use of therapeutic songs.  Songs with lyrics to one of the child’s favorite songs were created that served as directions for how to behave in certain social situations such has how to behave at the dinner table.  The children in the study engaged in the undesirable behavior less frequently after the song had been repeatedly sung to them over the course of a few days. 

One music therapist noted, “The information goes into the brain differently when you talk [compared to when you sing].”  This makes sense to me because it is usually significantly easier to remember something in song form compared to just memorizing lyrics.  For example, children learn the ABCs to the tune of a song.  I learned—and still remember—all 50 states alphabetical order thanks to a song I learned in 4th grade.   

The results from the work with autistic individuals make me curious about how and why the brain processes music differently than other sounds for everyone, not just autistic people.  Why is music calming?  Why does it help people remember things?  What is it about the input of music that results in these different outputs? 

Kathleen Myers's picture

Music and the mind

I think that music's capacity to aid memory and calm people is, in part, rooted its rhythmic and repetitive qualities-- that is, how it consists of and creates particular patterns.

In most preliterate cultures, traditional stories were sung or chanted, and while there were a variety of ways of telling these stories, certain word patterns generally appear ed again and again, as in Homer's Illiad and Odyssey. These word clusters had particluar poetic stresses- dactylic hexameter, I think, in the case of Homer- and worked as a mnemonic device for the storyteller. (But the use of them also permitted improvisation in response to the audience's or storyteller's own interests, just as with jazz music.) Also, many types of music and poetic rhythms mimic our biological rhythms (pulse, respiration, etc.), and while we may or may not be conscious of it, this surely this has a powerful effect on our perception and memory.

If behavior itself can be reasonably described as patterns of activity across motor neurons, it makes sense that music- a pattern of vibrational activity- effects the brain in very powerful ways. Loud, discordant music has even been used as a weapon by government agencies. I think I read somewhere that at ATF blared incessant heavy metal at David Koresh's Waco compound when they were trying to get  him and his follwers to evacuate the buildings.

leigh urbschat's picture

"Progress Is Reported on a Type of Autism"

Nicholas Wade's New York Times article (2/20/2007) "Progress Is Reported on a Type of Autism" informs readers that researchers are now able to correct a genetic defect in mice, that would cause Rett syndrome (a severe type of autism) in humans. Originally, scientists believed that a brain that does not wire itself correctly in its developmental stages will never be able to correct itself. Although the treatment will not work in humans, as the mice used were genetically engineered, it does give scientists hope as it is the first time they have been able to correct a neurological defect by restoring a missing component of the affected cells.

Scientists were able to engineer a new gene to put into the mice , which cuts out the mutated portion of the gene that causes Rett syndrome, known as MECP2. The second gene was then able to be "switched on" by giving the mice certain drugs. Shortly after the mice lost all signs of Rett Syndrome.

Although scientists still have far to go before any such process could be developed for humans, such developments provide optimism that someday autism will be overcome. We discussed in class how when we learn new things our brains are continually making new connections, yet here we are talking about erasing those connections which lead to problems. When we are able to both create and remove connections within our brains, will we then each have our own "designer" brain?

Meera Seth's picture

"Flame First, Think Later"

A recent New York Times essay (2/20/2007) by Daniel Goleman entitled "Flame First, Think Later: New Clues to E-mail Misbehavior" details a rather common and growing social faux pas which virtually all of us are guilty of committing from time to time. Classified under the umbrella of the developing field known as social neuroscience, this phenomenon is called flaming, or more technically "online disinhibition effect," which refers to one's increasingly unrestrained behavior in an online environment, such as e-mail and Instant Messaging.

Goleman reports that an article found in the CyberPsychology & Behavior journal cites multiple potential dynamics at play here, including "the anonymity of a Web pseudonym, invisibility to others, the time lag between sending an e-mail message and getting feedback, the exaggerated sense of self from being alone, and the lack of any online authority figure."

Biologically speaking, our social behavior is moderated by the circuitry concentrated on the orbitofrontal cortex, which serves as our primary foundation for empathy and ensures that we appropriately interact with others based on certain signals and cues, like facial expressions and various forms of body language. If we lack the opportunity to interact face-to-face, then we consequently lack the ability to read these key cues and react suitably.

This rather novel way of looking at the brain (that is, from a social perspective) raises several interesting issues involving attitudes toward (abnormal) human behavior and such behavior's causes and methods of treatment. Furthermore, we are compelled to question the value of new technologies. Are these tools really making communication easier? Or are they just creating more harm than good?

marquisedemerteuil's picture

this is a really good point,

this is a really good point, i go to imdb message boards for reality shows and people are really vicious. i think it's because people are anonymous and can secretly get out aggression that politeness with actual people prevents them from getting out. they can enact their fantasies -- haven't you ever wanted to just yell at some random person for having a bad idea? i have that all the time. all the time... if you're around people, you face a consequence for your yelling because you'll probably see that person again and have to work with them in some way, but if you're online, you don't know who you're talking about.

James Damascus's picture

The Prefrontal Cortex and Abstract Thought (repost)

(reposted in case people are interested in this article- this was posted a bit late) found an interesting article concerning the prefrontal cortex and abstract thought:                                                                                                                                                                                                                                                                     The article describes a 2001 study performed at MIT concerning pattern recognition and abstract thought. The study, in which monkeys apply rules about ‘same’ and ‘different’ images, shows that the prefrontal cortex works on the abstract assignment rather than simply recalling the pictures. In other words, the prefrontal cortex is involved in figuring out the rules of the “same/different” activity, rather than the simple performance of the activity. What is innovative about this approach to brain research is that it deals with abstract patterning and recognition, whereas traditional studies have focused on structures responsible for performing specific tasks, such as moving muscles or image recognition                                                                                                                                                                  The Study:                                                                                                                                                                Over a period of nine months, the researchers trained a group of monkeys to identify whether hundreds of different pictures were the same or different images. By recording signals from neurons in the prefrontal cortex of the monkeys as they performed cognitive processes, the scientists monitored the regions associated with “holding information in mind”, a requisite ability for information processing and thinking.                                                                                                                                                                                                                                                                                                                                                      The monkeys were trained to pull a joystick if a picture was the same as the one shown before. At other times, the monkeys were required to pull the lever to identify different images. The monkeys could apply the rule to pictures they had never seen before, showing that they were dealing with abstractions. By the end of the nine month period, the monkeys were able to respond instantly to the rule and were right more than 85 percent of the time.                                                                                                                                                                                                                                                                                                                 In studies of monkeys and humans with damage to the prefrontal cortex, researchers have found many of the same cognitive problems seen in schizophrenic patients. Among them is what is widely believed to be a disorder of working memory, which allows you to keep several pieces of information in mind simultaneously.  Abnormal functioning of the prefrontal cortex is implicated in schizophrenia, attention deficit disorder, obsessive-compulsive disorder and other diseases.                                                                                                                                                                                                                                                                              Why This Should Be interesting To Us:                                                                                                                                                                                                                                                                                                                                          The aim of this study is to gain some insight into what we’ve been referring to in class as the “I function” (the article uses the phrase “executive or cognitive control”). What this study suggests is that, although we know very little about abstract thought and its analogues, the responsible neurons are physiologically situated in the prefrontal cortex.  Although there are significant limitations to animal experimentation, and the specific physiological analogues associated with abstract thought remain unmapped, the investigative process is itself immeasurably valuable. If all of human experience is wrapped up in the phenommenon we call 'abstract thought', then potentially have much to gain from further research on the prefrontal cortex.

x's picture

This is Your Brain on...Love?

This study ( explains the differences in people’s brain when they’re in love and when they’ve been rejected, and the differences in the brain between being in love and experiencing lust. They found a couple of surprising things – first, that brains in love and brains in lust actually look very different, exposing the fact that love and lust are stimulated in different parts of the brain. This study also found that “When you fall in love exactly the same system becomes active as when you take cocaine. You can feel intense elation when you're in love. You can feel intense elation when you're high on cocaine.”

Love and lust are also connected in the brain through hormones. The study explains, “People in love have elevated levels of dopamine. Lots of dopamine, in turn, triggers the production of testosterone, which is responsible for the sex drive in both men and women.”

And, provocatively, the study explores differences between the male and female brain when experiencing love/lust. “The men had quite a bit more activity in the brain region that integrates visual stimuli…women in love had more activity than men in the areas of the brain that govern memories.”

This is a direct connection between brain and behavior. It seems to me there are a lot of other unexplained elements in this study. Is this connection the same for familial love? Pet love? Admiration/infatuation love? What would happen if people lied during this study? I wonder if people will eventually use this kind of brain imaging to find out if people “truly” love them.

Darlene Forde's picture

Hug me healthy . . . . hug me happy?

Steph’s response reminds me of an article I read in Prevention Magazine a few weeks ago, entitled “How Love Keeps You Healthy”. In the article, the author Sarah Mahoney compares the findings of several studies in an effort to understand the key features associated with love that have such a beneficial effect on the body. For example, in one study women in “good marriages” were found to have a lower risk of cardiovascular diseases, when compared to women who were in high-stress relationships. Similarly, ovarian cancer patients who were in “satisfying relationships” demonstrated higher levels of “desirable white blood cells” which are effective at destroying cancerous cells.

One of the main findings explored by Mahoney is that bonding and cohesion play an important role in both health and happiness. Bonding—or a “sense of being united” as Mahoney describes it—appears to help lower blood pressure. It also appears to be more effective than sex alone in fostering feelings of happiness and health. Mahoney also explores the findings of a few studies which examine the impacts of bear hugs on the nervous system. Researchers at UNC found that frequently daily hugging after a brief period of conversation “dramatically lower blood pressure and boost blood levels of oxytocin, a relaxing hormone that plays a key role in labor, breastfeeding, and orgasms.”

Oxytocin is a neurohormone, meaning that it is a hormone which also acts as a neurotransmitter. In the brain oxytocin is associated with feelings of bonding, stress-reduction, increased tolerance to pain, and sexual arousal. Both sexes release the hormone during orgasm.

I think it is important to stop here and reflect on the bonding in terms of the nervous system. What does our nervous system interpret as being connected? What exactly is a “sense of being united”? Is it a symphony of sensory neurons firing or motor neurons firing? Why does hugging trigger to elicit the release and/or production of oxytocin? Why was talking before hugging more effective fostering a sense of unity? Is the nervous system able to interpret the pattern more easily when that aspect is also present?

When Prof. Grobstein reached for the thermos on the lecturn on Thursday with his eyes closed, we speculated that this was a result of a Central Pattern Generator/Identifier. Is the nervous system programmed to associate talking and hugging to create a wider sense of identity and togetherness?

Cayla McNally's picture

I thought that this article

I thought that this article was really interesting, and really enjoyed the idea that being in a positive mental "place" while in love will have lasting effects on other parts of the body, not just the brain. However, like all studies that strongly rely on quantatative data, I think that the statistics in this article must be approached with a sense of caution. Whenever I read anything that involves statisitics that prove one thing and disprove another, I remember something I had learned in a previous class. It involved the study that stated that lower cholesterol is better for the heart, which is widely accepted and catered to in our society; however, what the study decided to leave out was that those who had lower cholesterol levels also had a higher suicide rate, because as cholesterol is lowered, so are the levels of hormones in the brain, such as serotonin. So while this article may state that people in positive, low stress relationships may have higher chances of being healthy, I wonder if that is the entire background information on the situation, or if there are things that were not included.

Sarah Powers's picture

An Input for Love

After reading this article, I understand that when you fall in love your brain changes, those sexy ventral tegmental areas are activated.  The study found that love is rooted in your brain like the hunt for food and water.  It is a physical need.  Well that expalins a lot about some human behavior.....Anyway.  My question is, what is the input for love?  Yes, we can percieve a love object through sight, smell, touch, but what is the right formula of these perceptions for you to fall in love with that person.  Do you need to know that someday they might return your feelings?  As this study showed, rejection from a love one is physically painful, so you would think human nature would make us want to avoid that at all costs. I think there must be some sort of individual standard for whom to fall in love with.  Otherwise, we'd all be falling in love with the same few people, and that could get really complicated really quickly.  Going along with the Emily Dickinson Model, this formula must exist in the brain somewhere, but it can't be static.  We can fall in/out of love with different people at different times, so that standard must change as we change.  The brain is in a constant flux taking in new information, comparing it with old information, sometimes it creates its own information.  This flow must contribute somehow to why we fall in love with those we do. 

michelle's picture

The L-word

I previously wrote a posting on love as well. I find this topic to be very interesting. Recently, my boyfriend and I have been getting serious and using the “love” word, which is what normal couples do after a while (I have to keep telling my self this to not be weirded out). Anyways, we both have had one serious relationship in the past and recently we’ve been dreaming about our past partners. I was thinking about why this may be and thought that maybe being in love for the second time triggers the release of neurons to be triggered that were triggered the first time around - similar to how memory is accessed. Also when reading Sarah Powers post regarding the input for love, I began to think of my own experiences. I remember how things that smelt like my boyfriend or reminded me of him released something to make me feel that “intense elation” that Steph talks about. I do think that it’s a combination of inputs.

Then I thought of love as whole. Although the study presents the chemical explanations of the emotion, I feel that it is an oversimplification of the experience and almost trivializes it. Like Sarah, I believe the concept of love varies from individual to individual and I remember asking a bunch of my friends how they knew they were in love and got a number of answers. The combination of inputs needed varies.

Now tying this into proprioceptors- I know people who’ve felt that their significant other “is the one”. Maybe knowing who our “soul mates” or “true love” is can be associated with proprioceptors. Learning about proprioceptors and all that other mind-blowing stuff about the brain makes me feel anything’s possible. But because proprioceptors are not controlled by our I-function, we might not know if the input is accurate or not as in the Phantom Limb syndrome. That’s when we need to step back and wonder if we’re in love, lust, or if our proprioceptors are lying to us, because we’d not want to make poor decisions about something as serious as love.

urbrainondrugs's picture

Brain Activity

I have taken a recent interest in brain scanners such as MRI scans, and fMRI scans. An fMRI (Functional Magnetic Resonance Imaging) is a technique that enables researchers to create maps of the brain's networks in action as thoughts, sensations, memories, and motor commands are processed. This "brain mapping" is achieved by setting up an advanced MRI scanner in a special way so that the increased blood flow to the activated areas of the brain shows up on Functional MRI scans. With this type of technique we can map the areas of the brain that become active whenever we perform our self proclaimed "motor symphonies". However, because an fMRI requires a scanner and stillness, it would be the mental thought of moving. An fMRI can show activity in the mind when giving an inner monologue. In an experiment, a subject would be given a task, such as thinking of a room with an obstacle course. They would be asked to mentally move themselves through the course by thinking of how each movement would propell them forwards through the track. In this way, we could track whether certain actions they must perform requires a greater amount of activity in the brain or if it is something that has already been pre-programmed.

A.Kyan's picture

Re: Brain Activity

To further add to fMRI's mapping brain activity, there have been recent studies using this technique to see what parts of the cortex are activated during meditative states.  (My paper is on this topic.)  It is very exciting that scientists are finding concrete evidence that meditation can improve memory, concentration, and attention areas of the brain.  Similar to working out your muscles, meditation is like a workout for the brain.  One can also think of professional muscians or athletes who have very active parts of the brain due to more use than the average person.  I wonder if our brains can be taxed too much to the point it gets injured or worn down like a sports injury.  We all feel mentally tired after studying for long hours or taking an intense exam.  Can our brains ever burn out from overuse?

It made me think of how I felt at the end of my four-month meditation retreat.  I was considering extending my stay for up to a year, but I was starting to feel extremely exhausted- mentally (plus I had school to come back to).  Actually, it was very peaceful to be in deep concentration most of the time, but who thought sitting/walking in meditation 14 hours/day could become tiring on the mind eventually?!  (The monks who were my teachers said that it's normal for the mind to become tired after a few months of intense training, then I didn't feel like such a lame-ass!)

secaldwe's picture


Taking into account this idea of a “motor symphony,” I wonder how the analogy would pertain to the creative brain – if it would be heightened at all, more apparent perhaps? Now that we know an action = motor symphony (as a contained movement), how does this reafferent loop work? I understand that the basic break-down of said symphony is motor neurons all doing different things at different times in a coordinated fashion, but where does the loop come into play? Does it record the movement? Does it conduct the movement? If I’m not mistaken, an element of input alteration is introduced, is it not? Any thoughts? I’m intrigued but very confused as to how to finish the metaphor!

Additionally, beyond the semantics of the symphony, I wonder if creative thought – as in “inspiration” (in dance, theater) – has any pre-programmed movements just as reaching for an object is imbedded in our nervous systems. Since it was stated that the ability to walk in humans does not depend on experience, what do we make of this notion of creative movement? Are prolific choreographers and actors simply recycling pre-existing functions of the nervous system but presenting them in new ways? Where does dance/movement even come from? What makes humans go beyond basic “pre-programmed” motions and make them into an art form? I’m trying to account for this notion that mostly everything we do in a day has been written into some inner code – that even with our eyes closed (like in the example of reaching for a cup of coffee) we would still be able to function and it wouldn’t be solely due to our experience. It is this idea of a pre-written score that really throws me for a loop – how many are there and how would we even know where to find them?

Shayna or Sheness Israel's picture

Who's/What's Doing theProgramming?

The Questions for me is pre-written where? In the I-function? In the collective consciousness? In cellular memory? Where is our mechanical, unthinking functions derived?


I believe the propioceptors can be filtered through the I-function. (I can teach myself to be as swift as a cat.) Is this not done through self-discipline? Is not what the great meditators, monks, and warriors are able to do? Drills rewire propriocetoric reactions and patterns, like what happens to soldiers in war and to dancers through rigorous dance classes. So, the original programming must come from consciousness or what we do. It would be interesting determine if one enters this world with a prior consciousness that begins to program the propioceptors…freaky.

alexa09's picture

procedural memory

I am not sure where certain functions such as walking are pre-written, but there is a name for memories like learning how to walk: procedural memory. Procedural memory is a type of implicit memory, in which past experiences help in the performance of the task without conscious awareness of these previous experiences. Procedural memory allows people to remember how to ride a bike without consciously aware of the execution of the procedure. We can use that example with walking. Most people (except for the man that Prof. Grobstein said could not hold himself up in the dark) do not have to consciously think about where their legs are and what motion they would have to perform next. Procedural memory is very interesting because it is separates our declarative memory in which people store facts and experiences. An experiment was done with amnesiacs with extremely impaired short term memory, where they were taught how to solve the puzzle of Hanoi. They improved the same amount after each try as did the control group although the patients said they don’t remember ever seeing the puzzle before.


RachelBrady's picture


I think you raise a good point when indicating that we can improve physical ability through repetition, and that these are ultimately due to changes in the nervous system. However, I feel that but saying that proprioceptive input is filtered through the I-function makes it too concrete and distinct, and would like to propose another theory. Our nervous system is infinitely complex and plastic; it is capable of modifying or eliminating pathways or parts of pathways. These modifications are based on how much the pathways are used, sort of a neural evolutionary process. Pathways that are infrequently used are reduced to maintain efficiency, while those that are used more often are modified to allow frequent use. In the case of your dedicated dancer, proprioceptors detect the usage of muscles contracted in order to perform a certain motion. When the pathway is continually activated it undergoes a process, as I imagine it, similar to the evolution of a species through natural Darwinism. The result is a more efficient pathway that caused the motion to appear more accurate, precise and seemingly free from conscious thought.  

Holly Stewart's picture

Epilepsy and Synaptic Potentials

I’ve been thinking a fair bit about these excitatory and inhibitory synaptic potentials and I find them quite interesting. An action potential is either excitatory or inhibitory, and for it to move from neuron to neuron there are conditions that need to be met. Action potentials are summed in the cell body of a neuron and if they have a strong enough intensity and/or frequency to bring the membrane potential above the threshold then an action potential is created. I guess that seems simple enough, to say that the system works in this way. But the problem is that it’s not always that simple. Yes, in the best-case scenario, everything works right and there are excitatory and inhibitory action potentials that work in harmony and everyone lives happily ever after.

So then, let’s talk about epilepsy. In the New York Times Science Times this week there was an article called, Battling Epilepsy, and Its Stigma which I found to be very interesting and very pertinent to our discussion this week. The article profiled a family in Pennsylvania whose 12-year old daughter, Nora has intractable epilepsy (this is a type of epilepsy that cannot be controlled with medication). Reading this article and watching the video stimulated questions but also promoted concerns about the way we think about neurological disorders.

Epilepsy is a neurological disease and affects almost three million Americans, half are children. Epileptic seizures can be thought of as there is either too much excitation in the brain or not enough inhibition. Huh. I found this description interestingly vague; it basically seems like we are covering the bases here with that definition. Isn’t that the reason that all behavior occurs: there is either not enough inhibition or too much excitation? Yet, Dr. Devnisky, the director of the epilepsy center at NYU is quoted as saying, “epilepsy just needs to be recognized as another neurological disorder.” (Granted, I am somewhat taking this comment out of context, but it still frustrates me.) True, epilepsy is just another neurological disorder, but just a neurological disorder?!? If Emily Dickinson is right, then just doesn’t cut it. There is so much about the brain, its support systems and what it controls.

Behavior, specifically looking at epilepsy isn’t just about excitation or inhibition, because then what causes you to snap out of it? In the case of Nora, I begin to wonder what else is going on. I think that Nora’s case is a prime example that there are other things going on in the system. Nora is now 12, but until recently had been seizure free for three years. She was able to stop having seizures because here parents put her on the ketogenic diet (this is a diet which induces a constant state of ketosis by feeding a diet rich in fat. Note that ketosis is an extremely severe condition and in diabetics can be fatal.). What is it about the ketogenic diet that worked so well, and not just for Nora, but for 50% of the people tested in the Johns Hopkins study? This diet stopped working for Nora recently and her parents blame it on her “growing up” and the “flow of hormones.” Again, I am unsatisfied by the answer (because it’s so vague), but also because it further illustrates the fact that behavior is under complex control systems, and it is not simply excitatory and inhibitory synaptic potentials.

But what about medication? The medication/treatment strategies are equally frustrating. There are lots of different epilepsy medications which do fundamentally different things, and when you are diagnosed with epilepsy they play guess-and-check until they find a medication that works for you. Yet, there are still 30% of epileptics who cannot control their seizures with medication. I want to first know if these medications are tailored to certain triggers (such as if you have too much excitation in your brain X chemical gets released) or if they are targeting something else.

I think epilepsy points further exemplifies the complexities that are responsible for behavior and also the minute amount of understanding we have of them. We know that these excitatory and inhibitory synaptic potentials exist and work most of the time, but they don’t work the same way or right in anyone. There are still more questions out there about behavior and how everything works together (or for that matter, doesn’t).

lrifkin's picture

Training Neurons?

In class today I was genuinely intrigued by the man who can’t “feel whether or not he is standing up.” After I got back to my room I decided to read further into his condition. However, my research has only left me with more questions.

I have discovered that the man who can’t “feel whether or not he is standing up” suffered from a viral infection that damaged his proprioceptiors. As a result he became unable to determine the position of his own body without looking and unable to feel things. Scientists have begun to call this ability to perceive one’s own movement and spatial orientation from within Proprioception, or our “sixth sense.” Generally, this perception occurs unconsciously, however, there are several examples of situations in which this process is noticed and challenged.

Ian Waterman, who we looked at in class, is not alone. There have been other, similar, recorded cases in which people have lost their sense of proprioception. In this situation, people still have control over muscle movement, are able to feel temperature, pain, deep pressure, and muscle fatigue. However, these individuals have lost their sense of touch and have lost control of the nerves attached to muscles and joints that provide them with information regarding limb and joint position. Thus, many of these individuals feel crippled. There have been instances of people in this situation choosing to spend the rest of their lives in wheelchairs, as well as instances of people choosing to remain ultra alert and to vigilantly watch every move they make. Through this extreme conscientiousness, people are able to somewhat make up for their loss of their “sixth sense.”

After reading about the ability to loose one’s sense of proprioception, I then discovered two instances in which the human sense of proprioception can be tricked into working when it is not needed. In one instance, subjects were asked to place their forearms and hands under a table. A fake limb was placed on the table, so as to look like it was attached to their upper arm. The fake limb was then tickled with a paintbrush as each subject received a brain scan. Within eleven seconds, everyone in the test believed that the fake limb was his or her own. The second instance I read about discussed phantom limbs of amputees. In this situation, amputees describe pain and sensation in the place where a limb has been removed years after surgery.

My post this week does not come to any conclusion but rather posits a question. From what I have seen, proprioceptors are extremely sensitive nerves. Alcohol, for example, is a strong enough agent to affect our sense of proprioception (people who are under the influence find it more difficult to walk in a straight line without looking down and to touch their noses). I wonder whether it would be possible to “exercise” or “train” neurons in order to strengthen them and avoid damage. I also wonder whether it would possible to “retrain” neurons, in order to help people such as Ian Waterman and amputees.

Sarah Harding's picture

Retraining Neurons

Your idea about retraining neurons is very interesting.  With regards to phantom limbs, I've read about how people with amputated limbs sometimes feel as though their invisible arm (leg, finger, etc..) is uncomfortably clenched.  In order to relieve the pain of this, a mirror is placed in the location of the amputated limb.  In the situation of a missing arm, the subject looks in the mirror and then moves his other arm, thus "tricking" his brain into believing that he is moving the non-existant arm.  Could this be an example of "retraining" neurons?  It obviously doesn't strengthen them or help them to avoid damage, but I feel as though this therapy may help to empower more inhibitory help the subject physically feel more comfortable.  If one is looking in the mirror, is this convincing enough for someone (such that the aforementioned man who can't walk without watching himself) to assume that they are looking at, and controlling an actual body part?  Can the deception of your mind be enough to create an action potential from a phantom limb?

csandrinic's picture

Propioceptors and the I-Function

Thursday’s discussion about proprioceptors was very interesting to me. If I understand correctly, proprioceptors are located in tendons, muscles, joints, and skin. They respond to stimuli generated by muscle movement and muscle tension and send signals to the brain regarding the position and movement of one’s body. However, all of these signals and messages, though they reach the brain, do not reach the I-function, and therefore we are generally not aware of them. Healthy proprioceptors allow for stability and balance. If proprioceptors are damaged, therefore, the nervous system becomes unable to send the proper nerve signal to the brain, and our notion of the position of our limbs would be incomprehensible. Whereas in class, we looked at the extreme case of a man named Ian Waterman who was completely incapable of determining how his body was positioned without looking at his body, there are also less extreme cases of the loss of sensitivity to the proprioceptors, such as aging and muscle or joint injuries. In the case of aging, as the sensitivity of the proprioceptor cells diminishes with age, they provide the brain with less of the sensory information it needs to maintain balance. This apparently, is the reason why one-third of people over the age of 65 fall at least once a year and incur injuries.

What I find so remarkable about the nature of proprioceptors is the capacity to re-train the nerve pathways in our nervous system to recognize the position of the joint in space. This retraining usually comes in the form of specific exercises related to improving and restoring balance. Doing these exercises is much like the way in which Ian Waterman is capable of moving by consciously paying visual attention to his limbs. Studies show that after three months of regularly performing movements aimed at sharpening balance, the vast majority of elderly subjects restored a level of body control and posture stability. What I understand from this is that the only way to stabilize the proprioceptors, which are in charge of unconsciously perceiving movement and spatial orientation, is to make a conscious effort to do so. In other words, the actions go through the I-function box rather than skipping it. Does this cancel out the function of the proprioceptors themselves? This fact makes me wonder whether the body is capable of functioning without them (although they are obviously extremely useful) by creating a back-up system in which conscious visual stimulation enables the body to be aware of its movement and posture. This would reinforce the theory that the brain and body are capable of creating ‘back-up’ systems and essentially rectifying a problem by creating a new solution.

Aditya's picture

Who's in control?

To sum some concepts from Thursday’s class, up we have proprioreceptors that send information about our place in our environment to the brain in reafferent loops, but not to the i-box (which explained why we did not know what angle our elbows were resting on the chair without looking at them), and as we make outputs this gets transmitted as reafferent information looped back to the nervous system which influence what inputs we are exposed to. Experiments showing flying in birds is not an innate behavior have implications for similar behaviors such as walking in humans. We have central pattern generators and preprogrammed patterns in our nervous system. Does this affect our destiny?

  If we have preprogrammed patterns of behavior in our nervous system, for example the pattern of how we walk, some people naturally walk faster with more energy or slower and more laid back and the pattern of walking is very consist and different for each individual… or in general if our overall body movements (something else pretty different and consistent per individual) are predetermined, how fast and slow we move, how animated we are, this would probably effect how people perceive us through our body language. The way people perceive us affects our life experiences. So is a certain amount of our life pre-determined by these central pattern generators?  

Another take on are we in control of our destiny is that we have proprioreceptors which send back sensory info to the brain but not the ibox. Does this mean there is some kind of executive functioning higher level program than the ibox that we are not conscious for that controls and guides our movements and makes certain decisions for us. We consciously only have control over the ibox, but does the rest of the nervous system control us? Are we in control of our own bodies? Think about it, if someone throws something unexpectedly at you, and you put your hands up to cover your face, did YOU put your hands up, do you remember thinking about putting your hands up? For me, my hands go up before I can fully comprehend what was going on possibly because another part of my nervous system sensed the danger before my ibox did. In addition, the neurons aren’t so seemingly simple as we first thought. They do analyze EPSP’s and IPSP’s, were compared to mini-computers, and are capable of complex and intelligent functions. How much control do we have our bodies?