week 4 - Neurobiology and Behavior

Is there really an I-function? Do we really have any say in our actions? What is the definition of free will? According to Mark Hallett, a researcher at the National Institute of Neurological Disorders and Stroke, "Free will does exist, but it's a perception, not a power or a driving force. People experience free will. They have the sense they are free.”

But the perception of being free does not necessary mean that it exists. According to Benjamin Libet’s research during the 1970s, Dr. Libet found that brain signals associated with random motions (such as pressing a button or flicking a finger) occurred half a second before the subject was conscious of deciding to make them. This means the brain perceives motion before it makes the decision to make it. From personal experience, I have experienced times when I make a decision without consciously realizing I am making the decision. When I was in fifth grade I went to an amusement park. There were people miming and a mime came up to a little boy and blew on a deflated balloon. The mime did this several times, before trying it to me; I blew on the deflated balloon and the balloon became inflated. Afterwards I realized I did not know when I made the decision to blow on the balloon; now I can only assume that my unconscious brain made the decision first before my conscious brain knew.

Action potentials have been described as “all or none.” The input has to reach a specific threshold before the neuron fires. Above this point, the intensity of the signal does not matter. The neuron will send the same signal regardless of whether or not the peak is higher than the necessary threshold. That talks about the “all” part of action potentials, but what about the “none” part? Are there some inputs that never reach action potential because they’re below the threshold point? Does a person never feel these inputs? I suppose sensory inputs that fall below the threshold point prevent us from being super sensitive. For example, every single minute piece of dust that brushes against our skin does not cause us excruciating pain. It seems that the “none” part of action potentials protects us from unimportant or insignificant stimuli.

Through discussions of neurons and receptors we learned that action potentials are the same throughout the brain, but are interpreted differently in different areas and receptors. This led us to wonder- “how much of reality are we perceptive to? Only that for which we have receptors?”

 In an article in last weeks New Yorker (Two Heads) similar questions were raised. The article was a profile of Patricia and Paul Churchland, philosophy professors who focus on Neuroscience and the “mind-body problem”. The most interesting point in the article was the idea that even if somehow at this time we were to suddenly come across the answer to what the mind is, perhaps we wouldn’t even know what to make of the answer because neuroscience is not far enough along. This leads me to wonder if we ever really can or will be far enough along- what kind of receptors are required in the human brain to understand the deep inner workings of the brain itself? Do we have those receptors- or will evolution perhaps lead to a development of such receptors? Or will an understanding of mind and consciousness remain in another reality that we are not open to- like high pitches heard by dogs and horses- we know it’s there, but we can’t really perceive it.

I want to talk about sound, vibrations and touch. In class we spoke about how humans cannot sense infrared because we do not have these receptors or we cannot feel magnetic fields because we lack these sensors as well. It brings up the question of sound? As the saying goes, if a tree falls and no one is there to hear it does it really make a sound? Well I want to ask my own question. If a tree falls and only a deaf man is present does the tree make a sound? Well, if sound is considered sound only if someone has heard it than in both cases the tree has not made a sound. However, if sound is considered a wave that vibrates from the ground as the tree falls then a sound was created in both instances. What about the deaf man? Can he hear the sound? If one takes a look at these two questions initially, the answer is clear, the deaf man cannot hear. But, if you think of sound as a vibration than why can’t the man feel the vibration? It’s as though I was at a concert, I can feel sound vibration if I’m standing close enough to the stage. The base is making vibrations that shake the stage and I don’t need to have proper hearing to feel these sound vibrations.

Another question posed is, if I couldn’t hear the sound and only felt the vibrations could I interpret what exactly I would hear if I weren’t deaf? Meaning would the music have been interpreted the same was through the vibrations I felt as opposed to the vibrations I heard? This brings up an interesting point, what about Beethoven? He became deaf in life and starting feeling the vibrations of the music to create his symphonies. He didn’t have sound receptors but how could he interpret what he felt into what it would sound like? Would his music have been the same if he wouldn’t have gone death? Its also interesting to think about what he thought his music sounded like and what it sounds like to someone who can hear properly? Is it the same? Are there any variations? If Beethoven didn’t need sound receptors to hear the music do we not need sound receptors to hear music? Do we have sound vibration receptors throughout our body that we, non deaf individuals, ignore? Maybe, we have different receptors on our body that aid our interpretation of sound but aren’t as pronounced until we lose our sense of hearing. These questions interest me a great deal. If this is the case, is it possible that humans have some kind of receptors for infrared or magnetic fields that aren’t pronounced in our bodies unlike fish and birds? What if one day we find these receptors? If we find them are they active or could they have mutated to an inactive form? These questions came up as I thought about Tuesday’s lecture.

The way neuorns work with the brain and everything is extremely interesting to me, however, what happens to the neurons of people who have agnosia? I know there are different types such as visual or prosopagnosia, but what exactly is missing in their brain that disable the neurons from travelling to and from? Is it ever curable?

I was reading through a neuroscience textbook this past weekend as well as some articles, and found an interesting article concerning the prefrontal cortex and abstract thought:     http://web.mit.edu/newsoffice/2001/abstractthought.html                                                                                                                                                                                                                             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 -- the part of the brain directly behind the eyes -- 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.  While there are certainly limitations to this kind of research, and, granted, we may never fully understand the physiological analogues associated with abstract thought and executive control, the investigative process is itself immeasurably valuable. If all aspects of human experience (philosophy, art, weapons of mass destruction) are byproducts of abstract thought, we have much to gain from neurobiological research.

The short answer to this question is, in fact, yes.

A relatively recent study conducted by scientists at the University of California, Santa Cruz has built on this information, providing interesting details to this phenomenon. They took a sample of 372 dreams from fifteen blind individuals, resulting in two independent analyses.

For the first analysis, a particular kind of software program created for the purpose of working with dream narratives was used to register the presence of the five senses in the dreams. With this equipment, it became clear that those individuals who had been blind from birth or very early in childhood had no visual imagery whatsoever, however did yield a high percentage of taste, smell, and touch references.

The second analysis revealed that according to several coding categories, the dreams included a high percentage of locomotion- and transportation-related dreams. Both the presence of sensory references and movement in these dreams are apparently evidence for the link between a dream's subject matter and conscious thought.

It's still really hard for me to get my mind around the concept that everything that occurs around me is interpreted through my brain and mind. I say both brain and mind because the neurons in the brain have to receive the stimulation that occurs to one of my senses, and my mind interjects previous experiences to further interpret what happens. A good example of the vastness of the capabilities of the brain is the myriad of colors the eye can perceive at the same time. The amount of shade variation that the eye can see is astounding, and equally interesting is the differences that occur between the way different people see the same colors. This is something that occurs everyday, without the majority of us being aware of this, and it's just one of the hundreds of processes that happen like that every day.

This week's discussion about the different functions that different neurons perform piqued my interest.  Although neurons have the same structure, they have the ability to impact a wide variety of behaviors.  This made me wonder if it is possible for us to strengthen certain neurons/behavioral processes more than others.  Can we train them to become stronger?  Take muscle memory for example.  Those who practice keyboarding become faster and are more efficient than people who are just learning.  Certainly if I had not practiced typing for so many years then I would not be able to type as quickly as I am able today. 
I thought that this idea was present in an article I read in the New York Times called Facial Recogniction: Faces, Faces Everywhere.  The article discussed peoples' ability to see faces in items ranging from clouds to grilled cheese sandwiches.  One idea is that our brain trains us to recognize faces over other objects so we are more likely to see them in non-human objects like potato chips.  Similar I to how we teach our muscles to perform certain actions, we teach our brain to do the same.  In other words, there is "particular area of the brain gives faces priority, like an airline offering first-class passengers expedited boarding."  This made me wonder why humans prioritize seeing faces and not hearing sounds for example.  It seems logical that we would see faces in non-human objects since faces are how we generally recognize people but this also made me wonder what kinds of things could go wrong if there was something wrong with the face recognition mechanism in humans. 

I understand how action potentials cause movement and reaction to outside stimulus. Furthermore, it makes perfect sense to me that having receptors depressed (i.e. touching something) can cause the sensation of touch, but how do thoughts cause action potentials? I’ve learned about action potentials several times now in my biology/psychology career and this point always gets me. I feel as though such a large portion of my every day happens in my head; thoughts, reading silently etc. Some of these thoughts generate actions ( i.e. thinking to sit down and write this post). But what I don't understand is how a thought is produced in the first place and then how this thought is able to generate an action potential. How do we think? How is a thought produced? How do our thoughts cause action potentials to occur and cause movement and sensations? There is still so much that isn't known about the brain that makes learning about it so fascinating.

According to the National Institute of Neurological Disorders and Stroke, there are more then 600 neurologic disorders. Unlike cancer, which is characterized by uncontrolled cell growth, neurodegeneration is characterized by cell death. There is still little known as to what causes the degeneration of neurons. There is ongoing research in this field that is making new discoveries and providing new insights into the underlying causes of these diseases.

In certain neurodegenerative diseases, such as Huntington's, it has been found that an accumulation of clumps of toxic proteins. Dyneins are tiny molecular motors that are responsible for moving proteins around in nerve cells. They are also responsible for getting rid of the toxic proteins in cells. However, as we all know, the development of human body is an extremely complicated process in which many mistakes can be made. Mamy complications arise from mistakes in the genetic information. So if there is a genetic mutation that causes dyneins to be absent or defective, then clumps of the toxic protein causing neurodegenertation will appear and the cell function will then be compromised.

A very important notion that we talked about in class is that we are only able to perceive what we have receptors for. We are only able to percieve a very small piece of everything that is occuring in our environment. However I don't think this is a bad thing because we are equipped with the senses we need for survival, nothing more nothing less.

In class we summed up some of the senses some other animals have that we don't: birds: magnetic field, dogs: high pitches, sharks: heat, butterflies: ultraviolet light, rattlesnakes: infrared light receptors, fish: electric fields. 

So is it bad that we dont have receptors to percieve these other environmental characteristics? Absolutely not. If at the same time we were perceiving the senses we are already able to perceive including all these others we would have too much input all the time, our environment would be a jumbled up picture to us, and our bodies much more complicated. Our body has evolved to be the most parsimonious in order for survival. It is a balance being simplistic (using the same A.P. currency for transportation of information from all senses) as well as having just the right amount of senses optimal for survival.

For example, birds use magnetic fields to fly to warmer climates. We are equipped with the intelligence and manueverability to create technology to keep ourselves warm in warm weather. We don't need to sense magnetic fields.

It is important to be conscious of the senses we don't have and the reality we arent sensing. We are able to create technology that allows us to perceive the pieces of reality our bodies cannot, which leads to further understanding of the universe.

I’ve been thinking a lot about these action potentials, and they seem quite interesting to me. We seem to be able to describe how they work, and somewhat even why they work (i.e. because of a stimulus). But my question now is: knowing all of this, are action potentials the limiting factor/the limiting component in our experience of reality? Let me explain where this question is coming from, because it seems a bit out there, I know…

Last week we talked about how action potentials work, they are a moving battery that propagates down an axon using selective membrane permeability and concentration gradients. On Thursday we furthermore talked about what makes action potentials work. We have a resting potential, which is effected when it is exposed to ions such as sodium and calcium and if there are enough ions present, a threshold is reached and an action potential is produced. Okay fine. I’m really okay with things up to about this point. But did anyone ever consider how complicated this simple system is?

Evolution is a conserved process: if it works and the environment supports it, then don’t try and fix it. So evolution has created this system relying on concentration gradients, membrane permeability, calcium, sodium and potassium; and it seems pretty lucky that all these ions are hanging out in the right concentrations right around the neurons so that when there is a stimulus action potentials can be created. But what happens when it doesn’t work? I spent a good couple of hours scouring the web (specifically PubMed) for scientific research showing what happens when these factors (ions, membrane permeability, etc.) are there: things don’t work. Well that makes me a bit uncomfortable. Granted adaptation happens over time, but evolution has given full responsibility to these ions and principles alone, across all the different types of neurons (motor, sensory, interneurons). The system is dependent on everything functioning as it should.

We (humans) are such an intricately designed system, extremely refined and well-developed, but so much so that it seems highly unlikely if not impossible for us to adapt. What happens if calcium stopped being transported and localized near our neurons? What would happen if the sodium/potassium pumps stopped working? Well, it may seem easy to say that we would die, but I want to even take a further perspective and say that evolution has already made some decisions for us. Evolution has already decided which ions it likes and which principles to base the system of action potentials off of, and it is going to keep using that system as long as the environment supports it. But, what if the system we are using has dictated the reality that we are able to be sensitive to? I would argue that it has.

For me then, it doesn’t seem that odd that we are only able to be sensitive and experience such a small piece of reality. Evolution has made a choice in humans, just as it has in birds and dogs, and I’m not really interested in speculating if that choice was good or bad, simply realizing that it has been made. I’m sure what made evolution respond the way it did or what implications it has, but I do think it is interesting to think that action potentials may in fact be the limiting factor in our sensitive and experiential reality.

I'm confused about the I-function.  Through meditation I have come to the conclusion that there is no "I" or a self, but only the mind and body working together (as I've posted earlier.)  But, I cannot deny that many twins (fraternal or identical) have a synergy in thoughts and feelings.  Especially when twins in different locales suffer the same injuries or sense the other twin is in danger.  How are two separate nervous systems and neuromatrixes somehow in sync?  This also goes for mothers' intuition and when people are able to sense a bad feeling that something has happened to a loved one, but can't explain it.  How do neuronal pathways make these connections?  Where do these inputs come from?  Scientists aren't likely to credit "psychic" abilities, but what is it in our brains that allow us to sense what is occurring in other people?  

This causes me to believe there is more to our brains than physiological pathways and connections.  What that may be, I'm not sure...  At the very least, I do not attribute it to a divine or spiritual power, but I do think it is within us to be extremely aware and access these abilities with the proper training.  Which leads me to believe that if there is such an I-function, than we can change or improve upon it.     

Today in class we began discussing the functional mechanisms of individual neurons. We also touched upon the idea that our perception of the world is limited to signals for which we have receptors. We can perceive signals which come to us in the form of light waves, sound waves (via vibration), chemicals, and tactile stimulation. We are unable to perceive such things as electrical or magnetic fields, and many visual/auditory/chemical signals that are outside our range.

This fact has many interesting implications. The one that occured to me has to do with what it is that makes humans different from other animals. I fully subscribe to the idea that there might be nothing that makes us substantially different, but while thinking about sensory perception I had a few ideas. At first I was a little indignant, why do we think of ourselves as so superior? Birds have a more complete experience of the world than we do, we cant even sense magnetic fields. But, as Prof Grobstein pointed out, we created the compass. We also came up with radar, sonar, and infrared goggles. Through our technology we have been able to compensate for our inadequacies, and expand on our abilities. Maybe one day we will be able to genetically alter humans so that we develop neurons responsive to magnetic fields, biologically aquiring the senses we lack.

The idea that we can expand upon our sensory capacities is not unrealistic. This is due to our neural plasticity, the ability of our neurons to change, and neural networks to take on new functions. Many blind people, both those blind from birth and those who lost their sight at an early age, are able to use echolocation to navigate their environment. These individuals are able to perceive aspects of their environment by observing how an emitted sound is altered as it bounces off of objects. Through the use of PET scans and fMRI's it has been shown that the visual cortex is active during this activity. This shows that the area of the brain typically responsible for visual processing is involved in auditory processing in these individuals. The visual cortex is also active when a blind individual reads braille.

The ability of our brain to change through experience and learning means that we are not so constrained by our biology. Neural plasticity is responsible for everything we do. Without it, if our brains were static, we could not learn or remember. Possibly we would not have any concept of self, any ability to integrate ideas. Everything would be in one ear and out the other