Sensory input and synaptic integration: implications

          At the beginning of the class we discussed how reality could be just a creation of our mind.  This is one of those ideas that people talk about and always seemed a little out there-a cool concept but a little “matrix-esque” to believe in on a day to day, person to person basis.  Maybe someone out there has the capacity to conceive of a different or “sixth” sense, but I certainly never thought it was me or anyone I knew well.  However, on closer consideration, and a smaller scale, I’m starting to see that reality, every day, monotonous reality, may be just a creation of my mind.  If I can only perceive senses that I have proteins for than it is a given that when I take in the world around me I’m not getting the whole (by no means exclusively visual) picture.   I guess that Tuesday’s discussion just made me reconsider reality as a perception and as unique to every person whose proteins are just a little different.

            It was also interesting to think about our “subconscious” senses and sensory processing (i.e. the pupil size exercise we did).  The idea that intuition can be based on actual perceptions we just don’t realize we are processing in some ways makes me more inclined to follow my “gut instinct”.  The ability to pick up on these signals from other people subconsciously is plausible; I wonder whether with a little effort one could make observations such as these conscious observations?ve the

A lot of people seem to still be having trouble conceptualizing the brain as a computer. I too am having this difficulty, but I think that is primarily because I don't know much about computers and computing networks. I was thinking a lot about the brain's plasticity--that is, it's ability to heal itself and make up for missing or damaged pieces--and ability to rewire or add new perceptions. I really like Caroline's observation that while computers cannot take much abuse in their hardwiring, brains seem to be quite able to do this. jwong continued this line of thought bringing up the brain's ability to gain new abilities, such as a "sense of direction."

I too find the ability of the brain to self-modify fascinating. I remember learning about a study where a woman was blindfolded 24/7 for a ridiculous amount of time while she was taught how to read brail. She was soon able to read brail as easily and quickly as actual blind people, which is not an easy task for seeing people. Most interestingly, when they measured activity of her brain while reading brail, they saw that the area normally used for processing sensory information was highly active. Thus, the brain used its vision center, which no longer was receiving visual input, to better process the sense of touch. Interestingly, however, when she was no longer blindfolded, she could no longer read brail as quickly and the her vision center was not as active while reading it. It seems as though that area's first concern is visual stimuli, but can also be used for tactile stimuli when not otherwise engaged. On a side note--could this finding help uncover something about synithesia? I'm not sure if they're relate, but the rewiring of senses sounds pertinent.

Going back to the question of the brain vs computer, I ask whether these abilities to heal, learn, adapt, and modify changes this analogy? We have stated that the brain may not be a computer, but a network of computers. Doesn't there have to be someone to rewire plugs b/w computers when there's something wrong? Certainly computer networks cannot grow new connections everytime something is learned. In this way, looking at the brain as a network is just as faulty as looking at it as a computer. However, as I said, I know very little about computers, so I may be mistaken... 

The idea of “knowing things without knowing how one knows them” is of particular interest to me because it seems to attest to the limitations and fragility of, in particular, human thought and behavior. If our mental faculties hinge upon the passive current flow of ions and the ability for our brains to translate sensory input via proteins into action potentials and other mechanistic processes, it makes sense that slight deviations from the expected range of outcomes can produce myriad outputs. The idea of “knowing without knowing how” is a tribute to Emily Dickinson’s idea of the “self” residing within the brain and of our infinite capacity to imagine, yet out very limited capacity to “know” that which is going on around us. The argument for our limited ability to perceive does not, to my mind, undermine the notion of agency. Given that the nervous system consists of many boxes connected to other boxes that can (and do) rearrange, that chemicals and batteries and membrane potentials exist does not mean that “self” ceases to exist. There must be some connectedness between the mind and the body or else, Descartes had it right…

The idea of there being a distinction between excitation in the brain and a “reduction in inhibition” is fascinating. This paradigm seems to enable the potential to explore behavior in ways that mere excitation and inhibition cannot. What is the nervous system of homeostasis? How much control do we (as the I-function) have over this? Does dis-inhibition suggest that we are constantly re-equilibrating in order to “control” our behavior? What makes something an “impulse” behavior as opposed to an “impulsive” one?

I've appreciated learning about synaptic integration because I think it further develops and problematizes the relationship between the brain, the I-function, the body, and the outside world. In contrast to what some people are saying, I actually think that I feel more of a connection to what we were talking about in the first week (with Dickinson, Descartes, and all the BIG questions) right now than I did a few weeks ago. Even though we're talking more about the physiological details, I think we're doing so in a way that does not simply take them at face value but instead harkens back to the complications of accepting any clear-cut dichotomies or definitions.

Our discussion of the senses, ESP, phantom limbs, and other topics related to sensory input have reminded me to avoid oversimplifying any distinctions I, or we, tend to make. Instead of arguing over the existence of a "mind" or setting aside all of neurobiology from all of behavior, it's evidently (if not obviously) more useful to talk about how one side of the argument relates to the other. From the beginning, we've said that there is not necessarily any short yes-or-no answer to the questions at stake -- nature vs. nurture, mind vs. brain, behavior vs. biology. If the I-function was helpful in terms of mediating between one side and the other or, better yet, probing deeper than pesky yes-or-no questions go, then I think the idea of synaptic integration goes even further: it shows that it's not enough just to ask if there is a mind or to wonder how the I-function interprets the outside world. Those questions don't take into account the fact that, as Prof. Grobstein emphasized in the last class, we're not doing justice either to the nervous system or to our behavior if we relegate complex, sometimes spontaneous, and notoriously massive webs of cells to relay systems.

Things go in; things come out; we can argue all day about what the inside and outside ARE or whether there's a distinction between them, but I appreciate that we're moving even further towards taking a stab at the muddy pudding in the middle! Personally, I don't really care one way or the other whether we compare humans to machines -- I just find it interesting to talk about the scale of the machinery and the quality of its connections.

Some questions re: details:

Does a connection to the I-function (i.e., for certain types of sensory inputs) have any affect on pre- or post-synaptic potential or its inhibition or on the types of neurotransmitters released into the synapse? I suspect not, but, still, I wonder if the I-function can increase or decrease inhibition.

By that same token, does a lack of connection, or diminished connection, to the I-function necessarily increase or decrease inhibition? If one's inhibitions are decreased upon drinking alcohol, is the alcohol affecting inhibition the same way across the body, or are the nerves receiving stimuli of which we're aware affected differently, or less, than the nerves doing things under our radar?

How does synaptic integration relate to the reception of specific types of stimuli? In the case of people with ESP, are the neurons receiving more or less, inhibiting more or less, or simply getting lost in the labyrinth of anatomical connections?

            I feel like we have deviated greatly from the discussion we were having towards the beginning of the semester. With all this talk of batteries and computers, it seems as thought we perceive the nervous system to be much more cut and dry than it actually is. 

            The nervous system is not an isolated apparatus that produces consistent results.  It is more likely that the nervous system is a tool that each individual uses to connect to the outside world.  The role of behavior in the input-output box that we have been addressing recently is something that I have forgotten about. I believe that behavior is the key to understanding the nervous system.  As the Harvard Law of Animal Behavior states, “an animal will behave as it damned wellpleases”.  If this is true, and I believe it is, that the link between the nervous system and behavior is very specific on an individual basis. In other words, if we believe that behavior is the external translation if the nervous systems then generalizing the nervous system might not be too helpful.  Because of the unpredictable behavior of animals, humans included, then it must stands to reason that solely studying the nervous system will not get you too far. 

            To bring this back to Thursday’s discussion, the input and output of a computer is very systematic and predictable, within reason.  However, we have already come to the conclusion early in the semester that behavior is unpredictable and therefore, as many people seem to agree, computers and the nervous system are incomparable.  

In the past I was one who would consider the analogy of the brain to a computer—in terms of being programmed or wired in a certain way, however I think the point that Caroline and Jenn pointed out that when wiring goes wrong for a computer it may crash, and lose all its ‘memory’—however a brain doesn’t lose necessarily all just by a error in a synaptic connection.

While researching the net about reasons why the brain is not like a computer I came across this website: http://skeptically.org/spiritualism/id8.html (although it has a weird name it did get me thinking)

Its arguments did seem a little scattered but it was the conclusion that made me start thinking about how it relates to our discussion. It mentions that the fundamental difference being is what the article calls “plasticity”. It goes on discussing how usage effects the development. It gives the example of those born congenitally blind but later their vision is restored slightly by an eye transplant. Although the person may regain vision by this transplant they are unable to gain ability to see with clarity—because they were born without the brain is adept for this function. However individuals who lose their vision due to trauma and then receive an eye transplant can have perfect vision restored. This example related to how the person born blind never had their visual cortex fully develop due to their genes. This is where usage effects development, in computers usage is determined by programming and chip designs, whereas it could be argued that perhaps the brain is pre-programmed by genes, which determines or sets the capacity of the brain and in a computer it is possible to re-program or override previous programming.

I was glad we ended our discussion on Thursday with ESP because it helped reground the idea that there is reality outside of our perception. I don't think it's out of line to think that some humans are more capable of sensing some things than others are. So, then, why is it so hard to believe that such a thing as the sixth sense (for humans) exists? Perception is merely relative; we don't know what someone else is or is not perceiving. Denouncing someone's ability of telepathy could be put on the same plane as someone with above-perfect vision, or a keen sense of smell. Our ways of measuring sight and smell (if there is any) are hardly flawless, so it shouldn't be argued that our five senses are measurable (how can you measure how accurate someone's sense of taste is?). Eyesight seems to be the only sense that we have tried to quantify in order to improve those who need artifical corrections, but none of our other senses can be quantified in such a way. Therefore, how can we know that when we experience deja vu or a chill, it's not a distant spirit coming to say hello? Maybe our perceptions are not as keen as a psychics in that regard.

Now, I'm not saying I believe in telepathy or psychics, but it seems interesting to me that, when talking of the senses, the idea of difficulty in quantification did not arise. When we think of ESP, we think of those who come off as hacks and exploit their "talents" for the sake of television like in "Crossing Over with John Edwards". But the point of this conversation is to show that we don't know if what you're looking at and what I'm looking at are actually the same color, and we don't know if John Edwards is really talking to distant spirits.

I also had a thought about people who can control their heart rate while meditating. Should this be considered to be a sixth sense? Because I-function is involved here, I would argue that it should be a sixth sense.

One more comment I wanted to make about last class is in regards to women's pheramones being responsible for timely menstruation. If we are thinking in terms of extrasensory effects on outwardly behavior ("knowing something without knowing it"), I find it hard to consider menstruation a behavior. Although at the beginning of class we agreed that breathing and heart rate and everything that happens internally are behaviors, I'm not sure it can be applied here. I might, instead use an example of conditioned behaviors. For example, people are often conditioned to behave in a certain way, and they are left "without knowing why" they behaved that way. I'd be interested to hear what others think of this analogy.

The idea that many forms of radiation (UV radiation, IR radiation, microwaves, X-rays, gamma rays, etc.) are not sensed by human sensory receptors but that they are likely sensed by other organisms was a familiar concept to me...but in the context of this class, I have come to think of this concept in a different way:

We concluded in the previous forum and also in class that a human could NOT know what it is like to be a bat, and that a bat could NOT know what it is like to be a human because of subjectivity. Additionally, we concluded that asking a dyslexic person "What is it like to be dyslexic?" is really no different than if a dyslexic person asked, "What is it like to NOT be dyslexic?" because of the subjective nature of these questions.

With the idea of subjectivity in mind, I decided to do some research on sensory reception in BEES (this was briefly mentioned in class), and to learn about what they are able to sense that we humans cannot. Below, I have pasted a link to a very informative page about sensory reception in bees. You don't have to read it too closely...but, in the context of our recent class discussions, see if a quick glance sparks the same questions for you as it did for me: How do we know what bees can or cannot perceive if we are NOT bees? Where are we getting these observations...from which we are making summaries?

While this site seems trusty (govt. of Arizona), sophisticated, and scientific...how seriously can we really take this information? Is this not just a summary of HUMAN observations? I think if bumble bees designed this webpage, we would have a trusty summary of observations. But until they gain this ability...how could we ever really know what they perceive?

http://gears.tucson.ars.ag.gov/ic/vision/bee-vision.html

When Professor Grobstein was elaborating upon the concept of proprioception, he asked us if we had to look at ourselves to make sure we were standing up straight. The example he gave was of a man unable to maintain postural control because of his loss of proprioception, so the question kind of makes sense. However, postural control and remaining upright is actually a fairly intricate task requiring more input from the environment than just "self-awareness."

In fact three systems are required to keep your head over your shoulders, and your shoulders over you knees. Balance is maintained by information provided by the visual system, the proprioceptive system and the vestibular system of the inner ear. (1) Proprioception and vision have already been briefly discussed in class, so I'm going to spend a little time discussing the vestibular system.

The vestibulum, along with the organs of hearing, houses the two organs responsible for detecting where we are in space: the semicircular canals (which detect rotation) and the otoliths (which detect linear translation and position relative to gravity).(2) We each have a set of three canals on either side of our heads (mirroring the three dimensions of our world) which work in a "push-pull" system, simultaneously inhibiting the other side when one is activated. The otoliths, each composed of an utricle and saccule, which function by detecting the displacement of hearing "ear crystals" suspended in in gel as we speed up or slow down ou turn our heads upside down. This system is also heavily reliant/bound up in the visual system, with both processes driving eachother to orient the body towards relevant events.(3)

So the man in the article Professor Grobstein presented to us presumably had an intact vestibular-visual pathway, because when he looked at himself he was able to translate the visual and vestibular inputs into postural control. Had someone with a vestibular pathology, like Meniere's disease, been asked to complete a similar task when denied proprioceptive information, they presumably would not have been able to. Even with body-awareness input, sufferers of Meniere's disease experience varying degrees of vertigo and have diffuculty maintaining balance (I know this from living with a person who has been diagnosed with Meniere's disease). So I guess this is just to say that perhaps there are more sensory modalities or modality combinations to consider when trying to translate from neurology to behavior.

1. http://en.wikipedia.org/wiki/Equilibrioception

2. http://www.physpharm.fmd.uwo.ca/undergrad/sensesweb/L10Balance/L10Balance.swf

3. http://www.bio-medicine.org/biology-definition/Vestibular_system/

Tuesday in class, the point was made that humans can only perceive those stimuli (such as light, sound, pressure differences) that can be picked up by proteins in our bodies.  The reason that we cannot perceive infrared radiation or radio waves is because we do not have the proteins to detect them.  However, we can perceive their existence through other apparatus that can detect them and that then translate them into stimuli that we can detect, such as the conversion of radio waves into sound waves.  So in this sense, we can perceive the existence of some things that we would otherwise not be able to experience in their original form.

Two ways in which we can come to perceive those things that we cannot directly experience is through 1) accidentally stumbling upon them empirically (through experiments that do not turn out as we expect, giving us a glimpse of something else that must be at work), and 2) conceiving of the possibility of something existing through theory and thought-experiments (extrapolating from previous experience or perceptions) and then devising a way to perceive it.  Of course the problem with this is that we can prove it with an experiment, but by “prove” I refer back to the lesson in the beginning of the semester, in which we discussed “getting it less wrong.”  When we use another apparatus to perceive the existence of those things that we cannot outright experience we are again limited in the same way as before with our bodies because our apparatus is also limited in what it can perceive (also, one might imagine, in what it can perceive and translate for us so that we also can perceive it).  We therefore cannot justify that science is objective because it is limited by what we can perceive and can get other things to perceive for us.  However, we could perhaps say that science can be objective if we refer to science as a description of the world that we can experience directly (this leaves such branches as quantum mechanics out of the definition because quantum phenomenon cannot be perceived directly).  Thus, science is objective if it is used to explain the reality that we experience through our five senses.

Thanks for your interesting responses! The pain/itch thing is odd indeed... and the tonic receptors sound like the perfect answer to my question. I wonder if they are called that/function the same way in humans? I hadn't thought of the Christopher Reeve example, but that does sound similar. I wonder how the neurons know which input is the same (i.e. continuing the constant input) and how they know if the input changes... maybe it depends on the intensity of the sensation, and if it becomes more intense, it triggers an action potential, but if it stays the same intensity the number of action potentials sent is limited, and stops after a while?