Two children were born into an abusive family. They were fraternal twins, and born at least fifteen years after their parents’ first child. Both grew up in the same house with the same ornery, alcoholic father and strict, unforgiving mother who often resorted to violence as a means of punishment. The twins were emotionally neglected and probably could have had better parents if the mother and father each transmogrified into a different type of rotten fruit. This will be case A.
In case B, another pair of fraternal twins was raised by an alcoholic mother and violent father, and had a much older sibling. Case C is identical to case A except the C parents annually made 200 thousand dollars more, and in case D the fraternal twins were raised by a rusty can and a turtle. Which of these four environments would most predictably elicit consistent aggressive, antisocial behavior in the respective sets of twins? Go ahead, guess.
If you chose any of them, you’d be wrong. It may very well be that all, none, or most of the cases above besides the can/turtle scenario produced callous, antisocial children, but no direct correlation exists. The behaviors the fraternal twins watch their parents perform consistently certainly impacts the children, but in no one specific way. Why not?
The process by which humans learn their behaviors and beliefs from the myriad environments each encounters as he develops–socialization–is simple to conceptualize, but inherently difficult to quantify. In the first case, it could have also been stipulated that one of the twins were homeschooled while the other attended public school regularly. The homeschooled twin spent disproportionately more time watching his parents interact with each other–watching them fight, curse, and attempt to inculcate within their child a dubious moral code while in a drunken haze–and the other twin spent each day watching how other kids his age interacted with one another. One day during kindergarten, the public-schooled twin noticed that whoever last left the classroom would have the teacher ask him to help clean up for a few minutes. Impatiently and consequently, he diverted more energy towards ensuring he wasn’t the last to leave; however, he saw that a couple of the other children scrambled more quickly than he did–more quickly than he could–to escape the room before they were the last and had to stay past the end of the school day. Feeling abandoned by his parents because he was stuck trying to run away from extra cleaning all on his own while his brother was homeschooled, he felt his only recourse was to take matters into his own hands, and he therefore began to start hiding his classmates’ belongings so they would have to spend the time he used to pack up and leave looking for their own things.
About a decade later, the same boy’s sibling, no longer homeschooled, rode the school bus everyday to high school, where he discovered that some of his peers more readily spent time with him if he could make them laugh. He wasn’t exactly sure how to do that, so he experimented with various styles of humor–slapstick, deadpan and the like–until he discovered that deprecating jokes almost universally elicited some giggles. Insults were, of course, fairly empty (if not downright stupid) without substance, and so there had to be a way for him to reconcile the need to make people laugh with his utter lack of knowledge about his peers. So he thought of his brother, the wunderkind who simultaneously smiled, did well in class, and went to parties every few weeks, and he came to conclude that he could joke about the brother who poorly rapped Eminem songs alone in his room. His brother’s idiosyncrasies were a hit with his friends, and as he become more comfortable around other kids his age, the deprecating humor gradually came to an end.
Another decade after that, the initially-homeschooled twin still lived with his parents while the publicly-schooled twin was a clever, successful accountant with an above-entry-level job at a firm in New York City. The latter brother had been working at the firm for almost two years, and he had been promoted thrice. He worked, on average, about forty hours each week, and had rented an apartment a few blocks from his job with a roommate he met in high school. The former twin spent most of his time writing fruitlessly in his bedroom, and usually fancied himself a published author–although he was not once–when he went out with acquaintances and the few friends he had managed to hold onto. He rarely spoke with his parents. Six months from this point in the twins’ lives, the homeschooled twin will finally finish and publish his first collection of short stories, and the accountant-twin will commit suicide.
What detail from this brief account of the two lives would lead anyone to conclude that one of the two boys eventually kills himself? Is the relevant detail even mentioned? Is there even a specific event that would have engendered it. Perhaps his job was too high stress and his aloof and distant parents hadn’t helped him learn how to cope, although it could be said that other accountants who had similarly negligent parents lived long and somewhat comfortable lives. Or, perhaps, one day he drank too much, remembered reading a story, years ago, about a girl who committed suicide, and was suddenly inspired. There are far, far too many confounding factors that make such conclusions almost impossible to draw, but it can, at least, be said that there are some genetic and environmental circumstances that will definitively impact someone’s socialization. For example, if the two twins were identical instead of fraternal (if they were monozygotic rather than dizygotic), it would have been more likely that both twins would have more readily exhibited aggressive, emotional behavior or that neither of them would. It is, of course, true that development due to the environment–ontogeny–could and does easily impact how aggressively anyone will act, and there is a more general, physiological description of the likelihood of aggressive, impulsive behavior than the identical twins scenario.
The ventromedial prefrontal cortex, the vmPFC, and a region of it known as the subgenual anterior cingulate cortex play a special role in inhibiting emotional responses: the vmPFC accepts input from the dorsomedial thalamus, olfactory system, temporal lobe, and the amygdala. From these regions, it receives information regarding the environment and what plans the other regions of the cerebrum are currently making, and outputs to regions such as the hypothalamus and amygdala in a way that allows it to affect emotional responses, often through inhibiting them. It’s the region of the prefrontal cortex that essentially checks aggressive, antisocial, impulsive, emotional, or violent behavior, if the behavior is inappropriate in a real, personal context. There was a man in the mid-1800s named Phineas Gage, who suffered from an accident involving a steel rod that exploded forward, through his cheek, and up out of his skull. He lived, but he was different. Before the accident, he was focused and had a good work ethic, but afterwards he became callous, irresponsible, and prone to emotional outbursts. Guess why.
The steel rod had destroyed most of his vmPFC, and as a result he acted much more impulsively, and also became almost entirely unable to make or keep plans. The region of his brain that once held his hand and sternly whispered in his ear don’t had been gimped. Of course, those who suffer from accidental impalements aren’t the only ones who act childishly, and so another explanation is possible. In London, cab drivers were once required to learn whole maps of London so they could get around more quickly, and it was shown that this requirement caused their cabbies’ brains to devote more neurons to the spatial memory center, the hippocampus. On average, London cab drivers have significantly larger hippocampi than you or I would. As discussed in the post Moral Dilemmas, children are more prone to emotional outbursts because their vmPFCs have not yet sufficiently grown as to more successfully inhibit the amygdala and the impulsive behavior it helps engender. Here lies perhaps the only quantifiable aspect of this discussion on anger and aggression: the bigger the vmPFC, the less likely a volatile reaction will occur.
Andrew Speers
Showing posts with label reflex. Show all posts
Showing posts with label reflex. Show all posts
Sunday, March 15, 2015
Friday, August 10, 2012
The Rhythm of Memories
I recently read an article from Discovery magasine called "Brainsong," in which the author had interviewed a neuroscientist by the name of Rodolfo Llinas. The string of questions concerned Llinas' perspective as to how the brain functions, and this perspective "emphasizes frequency, time, and coherence as much as anatomy and neurochemistry." Llinas has found that neurons intrinsically communicate with each other in low-level electric oscillatory rhythms, and that they do so intrinsically. That is, this rhythmic neural oscillation occurs without the need for any sort of sensory input. The generally thought of model of the brain is that it is akin to a computer, where it simply receives an efferent, sensory input, and then outputs a response using afferent motor neurons, however what actually happens is that incoming stimuli simply alter the inherent "chatting" that is already occurring between neurons of a given group, and then other neurons in that group will adjust to that altered oscillation frequency. This is similar to the beating of the heart: it can be slowed or sped up, but it will always pump, and, in the case of the neural oscillations, they can be increased or decreased in frequency, but they will still already be occurring. Furthermore, according to Rodolfo, regions of the brain that are involved in movement and coordination, such as the cerebellum, oscillate at 10 Hertz (Hz), or cycles per second, whereas faculties such as perception and cognition oscillate at 40 Hz, a frequency which is called gamma band. But, while Llinas' findings are indisputable, I stipulate that his interpretation of what they entail is mistaken. Why?
In my post "The Memory Circuit," I had said that memories are comprised of circuits of neurons which "loop" through different areas of the brain. What I did not say, however, is that each of these memory circuits are maintained by constant low-level electrical oscillations. These oscillations could be what Llinas refers to when he said the cerebellum oscillates at 10 Hz, something which he interpreted to be the simple functioning of the region. As I had referenced in my post "The Genius Gene," the brain stores basic statements, ideas or movements that it deems to be axiomatic in nature as memories, and then connects multiples of these simpler memories to form more complex conclusions. I think that the memory of a simple movement or complex behaviour would be comprised of a neural circuit which "loops" through corresponding regions of the brain, such as the cerebellum, and I further stipulate that the neuroscientist's observation of brain regions responsible for movement oscillating at 10 Hz instead refers to memory circuits that involve movements in their stored recollections. As a final point, I convict that if a memory circuit were to begin oscillating at 40 Hz, the individual would still only consciously recall it if multiple different cognitive stimuli were responsible for increasing the oscillatory frequency.
My next few posts will concern various points which Rodolfo Llinas made in the interview featured in a special edition of the Discovery magasine.
References
"Brainsong." Interview by Kat McGowan. Discover May 2012: 15-22. Print.
In my post "The Memory Circuit," I had said that memories are comprised of circuits of neurons which "loop" through different areas of the brain. What I did not say, however, is that each of these memory circuits are maintained by constant low-level electrical oscillations. These oscillations could be what Llinas refers to when he said the cerebellum oscillates at 10 Hz, something which he interpreted to be the simple functioning of the region. As I had referenced in my post "The Genius Gene," the brain stores basic statements, ideas or movements that it deems to be axiomatic in nature as memories, and then connects multiples of these simpler memories to form more complex conclusions. I think that the memory of a simple movement or complex behaviour would be comprised of a neural circuit which "loops" through corresponding regions of the brain, such as the cerebellum, and I further stipulate that the neuroscientist's observation of brain regions responsible for movement oscillating at 10 Hz instead refers to memory circuits that involve movements in their stored recollections. As a final point, I convict that if a memory circuit were to begin oscillating at 40 Hz, the individual would still only consciously recall it if multiple different cognitive stimuli were responsible for increasing the oscillatory frequency.
My next few posts will concern various points which Rodolfo Llinas made in the interview featured in a special edition of the Discovery magasine.
References
"Brainsong." Interview by Kat McGowan. Discover May 2012: 15-22. Print.
Monday, August 6, 2012
The Memory Circuit
In 1997, a doctor named Itzhak Friend experimented on a number of his epilepsy patients. He placed tiny brain activity monitors, or electrodes, in various regions of the patients' brains, and he then flashed various images of Marilyn Monroe at different rates to them. He had found that the same neurons, in a given patient's brain, were stimulated by different, yet similar images of Marilyn Monroe, as long as those neurons had been first exposed to a picture of her for the duration of a minimum time frame (less than a sixth of a second). Those neurons were also stimulated when the individual saw Monroe's name. Fried concluded that sets of neurons such as the ones stimulated by Marilyn Monroe are capable of retaining the "idea" of something (a place, an individual, etc.), for a brief period of time, and will be excited by stimuli which are similar to that idea. I stipulate this ability to be what I will refer to as short-term plasticity, or the ability of neurons to briefly alter their synaptic connections when posed with same or similar yet repeating stimuli in a small period of time (Plasticity, or neuroplasticity, is an ability of neurons I describe in my post "Habits, neuroplasticity, and the origin of emotion). Furthermore, this process is, essentially, the beginnings of a newly forming memory, and can be converted to one via long-term potentiation: the ability of neurons to alter their synaptic connections, in accordance with incoming stimulus, and to maintain that alteration for longer periods of time. But how and why does this conversion occur?
Memories tend to be more intense, and can be recalled more easily, if there is emotion associated with them. An example of this would be what is called, commonly, emotional scarring. This entails a situation which is so traumatic, or negative, in relation to a given individual, that the events of this occurrence are "burned" into the individual's mind ad infinitum. I would further convict that not only emotion, but the more mental processes, or faculties, involved in the memory, the more easily it can be recalled. For instance, learning is found to be easier if the subject interests the learner. Learning, as I had described in my post "The Genius Gene," is the process of the brain synthesising a new conclusion from multiple previously held memories that it deems axiomatic. Moreover, the brain is able to focus more of itself on certain processes or activities that it deems interesting via more widespread releases of a chemical called norepinephrine. Norepinephrine is involved in enhancing the vigilance, or attention to stimuli, of a given individual, and widespread releases of it will act on multiple regions of the brain, causing these regions to focus, more so, on the interesting process or activity. Therefore, the memory of the aforementioned new conclusion will be more easily remembered by the learner, if the subject at hand is one they find interesting. Another example of multiple mental faculties allowing easier recall of a given memory, as well as the associated memory or sensory information, would be cognitive association. The reason you are "reminded" of a particular memory in relation to an incoming stimulus is because one of the three lobes of the cerebrum responsible for cognitive association (the temporal, parietal, and occipital lobes) have associated that stimulus with the memory. And, the more stimulus associated with a memory, the greater the probability of, as well as ease in, the brain's recollection, because multiple different regions of the cerebrum would be involved in that remembrance (the brain is able to process more quickly depending on the amount of white matter involved in making the relevant connections, ergo the more regions of the brain involved, the faster the recollection). This concept correlates directly with multiphasic cognitive relay, a process I describe in my post "Subjective Perception." I suppose that just as multiple cognitions create the illusion of the individual being aware of that cognition, and just as multiple cognitions or mental faculties involved in the recall of a memory speeds up the process, the individual will be aware of that recall so long as multiple different cognitive associations are made by the cerebrum. In other words, the individual will become aware of the recollection of a memory if the brain had processed and stored multiple different stimuli regarding that memory, and if that information is being associated with other multiphasic cognition, be it present perception, past perception, or the frontal lobe formulating a strategy or behaviour. The remaining question, though, is how are these memories converted from short-term plasticity to long-term potentiation, and then stored?
A set of proteins, known as protein kinase, are responsible for a number of different regulatory functions. A recently discovered class of protein kinase, known as PKM-Zeta, is the single protein which is responsible for the maintaining of long-term potentiation between neurons. This protein acts as a sort of "glue" which keeps intact the altered synaptic connections, connections originally altered by the preceding short-term plasticity. Moreover, as I had stated in the previous paragraph, that the more mental faculties involved in a memory, the more easily it can be recalled, I stipulate that this is due to the nature of memory storage in the brain, a nature which I will describe as a memory circuit. A memory circuit is an interconnecting set of neurons, held together in the long-term by PKM-Zeta, that processes, or "loops," through the different regions of the brain that had been active in regards to the memory at the time of said memory. These regions are then stimulated in the same or similar manner as they had been, and this similar stimulation causes the individual to be "reminded" of the previous instances when it had occurred. As discussed in my post "Habits, Neuroplasticity, and the Origin of Emotion," neurons can undergo neuroplasticity and alter their synaptic connections in such a way that matches repeated stimuli, and I further stipulate that this neuroplasticity is the foundation on which a memory circuit is formed by the brain. As my final point, I convict that short-term plasticity is converted to long-term potentiation so long as the repeating stimuli which caused the short-term plasticity is repeated for a longer period of time. This time frame can vary depending on the intelligence, or speed at which an individual's brain makes connections, of the given individual.
I have been receiving a number of requests to create entries in regards to a number of different concepts, such as drugs and positive association. I will, in due time, write these, however for now I must start with one of the principal bases of brain function: the memory circuit.
Memories tend to be more intense, and can be recalled more easily, if there is emotion associated with them. An example of this would be what is called, commonly, emotional scarring. This entails a situation which is so traumatic, or negative, in relation to a given individual, that the events of this occurrence are "burned" into the individual's mind ad infinitum. I would further convict that not only emotion, but the more mental processes, or faculties, involved in the memory, the more easily it can be recalled. For instance, learning is found to be easier if the subject interests the learner. Learning, as I had described in my post "The Genius Gene," is the process of the brain synthesising a new conclusion from multiple previously held memories that it deems axiomatic. Moreover, the brain is able to focus more of itself on certain processes or activities that it deems interesting via more widespread releases of a chemical called norepinephrine. Norepinephrine is involved in enhancing the vigilance, or attention to stimuli, of a given individual, and widespread releases of it will act on multiple regions of the brain, causing these regions to focus, more so, on the interesting process or activity. Therefore, the memory of the aforementioned new conclusion will be more easily remembered by the learner, if the subject at hand is one they find interesting. Another example of multiple mental faculties allowing easier recall of a given memory, as well as the associated memory or sensory information, would be cognitive association. The reason you are "reminded" of a particular memory in relation to an incoming stimulus is because one of the three lobes of the cerebrum responsible for cognitive association (the temporal, parietal, and occipital lobes) have associated that stimulus with the memory. And, the more stimulus associated with a memory, the greater the probability of, as well as ease in, the brain's recollection, because multiple different regions of the cerebrum would be involved in that remembrance (the brain is able to process more quickly depending on the amount of white matter involved in making the relevant connections, ergo the more regions of the brain involved, the faster the recollection). This concept correlates directly with multiphasic cognitive relay, a process I describe in my post "Subjective Perception." I suppose that just as multiple cognitions create the illusion of the individual being aware of that cognition, and just as multiple cognitions or mental faculties involved in the recall of a memory speeds up the process, the individual will be aware of that recall so long as multiple different cognitive associations are made by the cerebrum. In other words, the individual will become aware of the recollection of a memory if the brain had processed and stored multiple different stimuli regarding that memory, and if that information is being associated with other multiphasic cognition, be it present perception, past perception, or the frontal lobe formulating a strategy or behaviour. The remaining question, though, is how are these memories converted from short-term plasticity to long-term potentiation, and then stored?
A set of proteins, known as protein kinase, are responsible for a number of different regulatory functions. A recently discovered class of protein kinase, known as PKM-Zeta, is the single protein which is responsible for the maintaining of long-term potentiation between neurons. This protein acts as a sort of "glue" which keeps intact the altered synaptic connections, connections originally altered by the preceding short-term plasticity. Moreover, as I had stated in the previous paragraph, that the more mental faculties involved in a memory, the more easily it can be recalled, I stipulate that this is due to the nature of memory storage in the brain, a nature which I will describe as a memory circuit. A memory circuit is an interconnecting set of neurons, held together in the long-term by PKM-Zeta, that processes, or "loops," through the different regions of the brain that had been active in regards to the memory at the time of said memory. These regions are then stimulated in the same or similar manner as they had been, and this similar stimulation causes the individual to be "reminded" of the previous instances when it had occurred. As discussed in my post "Habits, Neuroplasticity, and the Origin of Emotion," neurons can undergo neuroplasticity and alter their synaptic connections in such a way that matches repeated stimuli, and I further stipulate that this neuroplasticity is the foundation on which a memory circuit is formed by the brain. As my final point, I convict that short-term plasticity is converted to long-term potentiation so long as the repeating stimuli which caused the short-term plasticity is repeated for a longer period of time. This time frame can vary depending on the intelligence, or speed at which an individual's brain makes connections, of the given individual.
I have been receiving a number of requests to create entries in regards to a number of different concepts, such as drugs and positive association. I will, in due time, write these, however for now I must start with one of the principal bases of brain function: the memory circuit.
Saturday, July 28, 2012
The Genius Gene
How do we understand things? In a geometry class, the student is first exposed to what is known as a postulate. A postulate is a statement that is so simple and basic in nature that it is axiomatic, and can be considered as such without the need for evidence. For example, the ruler postulate dictates that every point on a line can be assigned a real number. After the student becomes acquainted with several postulates, he will then be introduced to what are known as theorems: statements which are proven by use of previously established statements, or, in this case, postulates. The process of using previously known statements regarded as fact in order to prove something else, more complex in nature, to be true is how we learn. At a young age, children are taught basic principles of mathematics, such as numbers. They are taught to accept that each number has its own value, and that each number that supersedes any other given number has a greater value. Based on these two statements, they can then conclude that if two numbers were to be combined together, their collective value would increase at a rate relative to the values of the original, independent numbers. Needless to say, it is not explained in this manner, however therein lies a question: how does this manifest on a neurobiological level?
Refer back to the example of the child learning basic principles of math. In order to understand that two numbers such as two and three equate to five, his brain must first establish the original two statements as fact, and does so by storing them as memories. In the same way, the brain uses the memory of the experience of, for instance, seeing the clear sky as blue, to set what might be considered an intellectual precedent, and thereafter the individual will always make the assumption that he will see the clear sky as blue. It will then use the memories of the aforementioned mathematical principles to conclude that two and three equate to five. In other words, the brain connects the two memories together, and combines them, and will understand the more complex concept of addition due to this memory combination. The newly conceived concept will then enter into the process of becoming a long-term memory (not relevant to this post). The connections between the two memories are made by what are known as axons: long, slender tubes which project from the cell body of a neuron (a cell of the nervous system that transmits information) which transmit information between different regions of the nervous system. For the purposes of this entry, simply assume that there are a pair of axons which allow for intercommunication between the two memories. The axons are known collectively as white matter, because they are coated in a fatty substance (known as the myelin sheath) that is coloured white. Furthermore, we can assume that because the axons of the white matter form connections between memories, allowing more complex concepts to be conceived and understood, the ability of an individual to understand these concepts, which is known as intelligence, is directly correlated to the amount of white matter in that individual's brain. But what dictates the amount of white matter in a person's brain?
While intelligence has been known to change throughout childhood development, the amount of white matter in an individual's brain is dependent on the genes which control the development of the brain of a baby during pregnancy, development which is referred to as neonatal neural development. Neil R. Carlson's The Physiology of Behaviour describes the process in which the nervous system forms. Early in embryonic development, a portion of the ectodermal (out layer) tissue of the embryo hardens into a plate, which then curls into what is called the neural tube. This tube will develop into the spinal cord, and the cells at the top of the tube will begin to divide and produce neurons and other nerve cells in the brain, which will then also be positioned by the cells from whence they divided. After these cells fall into their designated places, they will begin to sprout axons as well as small, branchlike processes known as dendrites (refer to the figure below). These axons will attempt to find other neurons to connect to, and ones that fail to do so will undergo apoptosis, or programmed cell death. The cells, of course, are programmed to do so by their genes. I stipulate that if one of the genes responsible for causing neurons whose axons do not make connections with other neurons to undergo apoptosis was perhaps faulty in some way, then maybe some or all of those neurons might remain alive, and they could then be able to form connections with other neurons (as neurons continuously do throughout life) after the child is born. This increase in white matter due to the faulty gene (or genes) would therefore correlate to an increase in the potential intelligence of the child, or perhaps even allow for the possibility of what might be interpreted as genius.
As I had said in my last post, my stipulation as to the possibility of this "genius gene" is just that- stipulation. It is a hypothesis I do not yet have evidence for or against, nor do I at the moment have means of acquiring any beyond reading the work of others. As with my post on the 'decision reflex,' though, I find this concept as well entirely plausible, and will continue to broach my ideas concerning neurobiology and the state of what we perceive to the internet using this blog.
References
Refer back to the example of the child learning basic principles of math. In order to understand that two numbers such as two and three equate to five, his brain must first establish the original two statements as fact, and does so by storing them as memories. In the same way, the brain uses the memory of the experience of, for instance, seeing the clear sky as blue, to set what might be considered an intellectual precedent, and thereafter the individual will always make the assumption that he will see the clear sky as blue. It will then use the memories of the aforementioned mathematical principles to conclude that two and three equate to five. In other words, the brain connects the two memories together, and combines them, and will understand the more complex concept of addition due to this memory combination. The newly conceived concept will then enter into the process of becoming a long-term memory (not relevant to this post). The connections between the two memories are made by what are known as axons: long, slender tubes which project from the cell body of a neuron (a cell of the nervous system that transmits information) which transmit information between different regions of the nervous system. For the purposes of this entry, simply assume that there are a pair of axons which allow for intercommunication between the two memories. The axons are known collectively as white matter, because they are coated in a fatty substance (known as the myelin sheath) that is coloured white. Furthermore, we can assume that because the axons of the white matter form connections between memories, allowing more complex concepts to be conceived and understood, the ability of an individual to understand these concepts, which is known as intelligence, is directly correlated to the amount of white matter in that individual's brain. But what dictates the amount of white matter in a person's brain?
While intelligence has been known to change throughout childhood development, the amount of white matter in an individual's brain is dependent on the genes which control the development of the brain of a baby during pregnancy, development which is referred to as neonatal neural development. Neil R. Carlson's The Physiology of Behaviour describes the process in which the nervous system forms. Early in embryonic development, a portion of the ectodermal (out layer) tissue of the embryo hardens into a plate, which then curls into what is called the neural tube. This tube will develop into the spinal cord, and the cells at the top of the tube will begin to divide and produce neurons and other nerve cells in the brain, which will then also be positioned by the cells from whence they divided. After these cells fall into their designated places, they will begin to sprout axons as well as small, branchlike processes known as dendrites (refer to the figure below). These axons will attempt to find other neurons to connect to, and ones that fail to do so will undergo apoptosis, or programmed cell death. The cells, of course, are programmed to do so by their genes. I stipulate that if one of the genes responsible for causing neurons whose axons do not make connections with other neurons to undergo apoptosis was perhaps faulty in some way, then maybe some or all of those neurons might remain alive, and they could then be able to form connections with other neurons (as neurons continuously do throughout life) after the child is born. This increase in white matter due to the faulty gene (or genes) would therefore correlate to an increase in the potential intelligence of the child, or perhaps even allow for the possibility of what might be interpreted as genius.
 |
| A basic visual of a neuron, a nerve cell, which displays the axon and dendrites. |
References
Carlson, Neil R. Physiology of Behavior. Boston: Allyn and Bacon, 2011. Print.
Felten, David L., Anil Narsinha. Shetty, and David L. Felten. Netter's Atlas of Neuroscience. Philadelphia, PA: Saunders/Elsevier, 2010. Print.
Friday, July 27, 2012
The Decision Reflex
What are humans? Certain religions would have us believe we are the center of the universe, however from a scientific and secular viewpoint, we are simply one of the myriad of products of a long and winding evolutionary 'road.' We are the last surviving species of the genus 'homo,' however we are still organisms, as are house cats and fruit flies. What makes us different is the long-held concept of consciousness, or a higher level of thinking than most of the animals with which we cohabitate the world. Does this entail that there is something more in us, as homo sapiens, than there are in other organisms such as horses? Or are we composed of the same six elements, and bound together by electricity and atomic bonds, just as every other organism that lives or has once lived? Science has long ago proven the latter to be true, although the nature of consciousness itself has eluded our full comprehension. In this post, I am going to broach my hypothesis as to how the 'mind' functions, as well as support it.
What would happen if one's finger was placed on an source of immense heat? The body would react by immediately retracting the finger, or perhaps the entire arm. However this is not voluntary. In a situation such as this one, the nerves in the finger which sense the heat communicate that intense sensation to the spinal cord, which is a 'cord' of neural tissue (nerves and cell bodies of nerves), where it meets another nerve that will then send that communication back to the point of the sensation's origin, where muscles in that general area will react by contracting, thus pulling the finger backwards. Only after this process, known as a reflex, will the individual become aware of it, because the spinal cord will also project this information to the brain, but by the time the individual might reach a state of awareness of the sensation of heat (in most cases, less than a second) the reflex will have already been completed.
Suppose the reflex described in the previous paragraph did not occur, and that in order for the finger to be pulled from the heat, the brain must make the decision to retract it. The same nerves in the finger would sense the heat, and communicate it to the spinal cord. The spinal cord would send the information to the brain, where it would pass through a number of systems until it reached a particular area of what is known as the cerebrum. The cerebrum is the largest portion of the brain, and what most think of when they attempt to visualise it. It is divided into two portions, which are known as the cerebral hemispheres. It is the topmost region of the brain, and its cortex ("bark" in Greek), or the external layer, has many grooves and fissures in it, and these are known as cortical folding. The cortex of the cerebrum is called the cerebral cortex, and the frontal portion of the cerebrum is called the frontal lobe. Each cerebral hemisphere has a frontal lobe, as well as one of each of the other three lobes (they are not to be referenced in this post), and the two hemispheres are connected by what is called the corpus callosum ("tough body" in Latin), which allows the two hemispheres to share information with one another (see the below figure). The frontal lobe is responsible for planning movements, strategies, and things of that nature (all of which can be conscious processes), and the information the aforementioned nerves received from the heat source would have to be processed by the frontal lobe, and then processed back to the point of the sensation's origin before the finger would be retracted. But what exactly causes this process to become 'conscious?'
According to Sam Harris, a neurologist as well as author of a number of books including Free Will, the decision making process of the brain is principally subconscious in nature: that is, the decision is made before the individual is aware of it. The time it takes the individual to become aware of the decision is, as it was in the case of the reflex, much less than a second, although it has led myself to stipulate that perhaps the process of making a decision is akin to a reflex, and that the individual becomes aware of it due to the information being sent to a different region of the brain, as one might become conscious of a reflex due to the spinal cord sending the information concerning it to a different region of the nervous system: the brain. Therein lies another question: which region?
Neil R. Carlson's eleventh edition of his textbook The Physiology of Behaviour references a procedure known as the split-brain operation. This operation is performed on those afflicted with epilepsy so severe that it cannot be controlled with drugs. Epilepsy is a disorder in which the nerves of one of the cerebral hemispheres becomes overactive. Those nerves then process through the corpus callosum, and cause nerves in the other hemisphere to become overactive, resulting in what's known as a seizure. The purpose of the split-brain operation is to cut the corpus callosum, so that the overactive neurons cannot reach the other hemisphere. This prevents the hemispheres from taking part in interhemispheric communication, or the sharing of information and perceptions between hemispheres, as well as causes rather interesting side effects. In a case referenced by the same text, a post-op split-brain patient had been reading a book. The book was in the patient's left hand, and the holding of the book therefore correlated to the right side of the brain (connections to the brain are inverted, i.e. left hand to right hemisphere, etc.). In the brain of this patient, the right hemisphere could not interpret individual components of something, such as words to a text. Because the right cerebral hemisphere could not read what the book said, it became bored with it and caused the left hand to throw it away. When it was later discussed, the patient was not aware that the right hemisphere had decided to do so, and simply witnessed his own hand "having a mind of its own." In his textbook, Carlson has interpreted this as a region of the left cerebral hemisphere being involved in consciousness, and I would agree with this. However, I would further stipulate that it is not the only region of the cerebrum so involved, so much as any region besides the one from whence the communication originated.
For example, perhaps the frontal lobe is planning to contract the humerus, the long bone in the forearm. The individual is at first not aware of this, however becomes so when the frontal lobe communicates with one of the regions of the cerebral hemisphere, either ipsilateral (on the same side) or contralateral (on the other side) to it, that is responsible for associating vision, audition, or other sensory information with memories. At the point in which these two regions of the brain communicate, is the point at which the individual becomes aware of the frontal lobe's current activity. An analogy which might be employed to conceptualise this process would be two individuals who are having a conversation, and a third who is listening in. Equate one of the conversing individuals, individual A, to the frontal lobe, and the other individual, individual B, to the region to which the front lobe is communicating with. The third person (individual C) is the individual whose brain this is occurring in. Individual A is planning to buy a pizza to eat. Individual C is not yet aware of this because individual A has not shared this plan. When he shares it with individual B, individual B can help individual A figure out where to buy the pizza and how much it might cost. Individual C is not aware of how each of the individual are forming these ideas, however he has now become aware of the plan to buy the pizza due to his listening to the communication between individuals A and B. This is what I convict consciousness to be: the communication between different regions of the cerebrum, or perhaps between regions of the cerebrum and different areas of the brain in general.
In the paragraph previous to my analogy, I stipulated that the region of the cerebrum that did not communicate with the right hemisphere (due to the split-brain op) in the patient was not the only one involved in consciousness. Why? The patient was not aware of the right hemisphere's boredom with the book, nor was he aware of its plan to throw the book away, which was due to the procedure performed to cure his severe epilepsy. Would that then not mean that consciousness is isolated to only one hemisphere (left, in this case) of the brain? Not necessarily, otherwise how would the individual have made the decision to read the book in the first place? As I had mentioned previously, I convict the process of formulating plans and decisions is a subconscious one, and that this decision 'reflex' would cause the individual to become aware of it after the fact. My hypothesis would entail the region of the brain that received the communication from the frontal lobe about its plan to pickup the book caused the individual to become aware of it, however the region of the brain that was supposed to receive information from the frontal lobe of the right cerebral hemisphere about its boredom of reading the book had been disconnected due to the split-brain operation, thus preventing the individual from becoming aware of it.
This is but one of the many ideas I have concerning the brain and the nature of consciousness, and while I cannot yet ascertain whether or not there is truth in the concept of a 'decision reflex,' I deem it to be entirely plausible, and I look forward to being able to either prove or disprove myself in the future, when I have the means to.
References:
What would happen if one's finger was placed on an source of immense heat? The body would react by immediately retracting the finger, or perhaps the entire arm. However this is not voluntary. In a situation such as this one, the nerves in the finger which sense the heat communicate that intense sensation to the spinal cord, which is a 'cord' of neural tissue (nerves and cell bodies of nerves), where it meets another nerve that will then send that communication back to the point of the sensation's origin, where muscles in that general area will react by contracting, thus pulling the finger backwards. Only after this process, known as a reflex, will the individual become aware of it, because the spinal cord will also project this information to the brain, but by the time the individual might reach a state of awareness of the sensation of heat (in most cases, less than a second) the reflex will have already been completed.
Suppose the reflex described in the previous paragraph did not occur, and that in order for the finger to be pulled from the heat, the brain must make the decision to retract it. The same nerves in the finger would sense the heat, and communicate it to the spinal cord. The spinal cord would send the information to the brain, where it would pass through a number of systems until it reached a particular area of what is known as the cerebrum. The cerebrum is the largest portion of the brain, and what most think of when they attempt to visualise it. It is divided into two portions, which are known as the cerebral hemispheres. It is the topmost region of the brain, and its cortex ("bark" in Greek), or the external layer, has many grooves and fissures in it, and these are known as cortical folding. The cortex of the cerebrum is called the cerebral cortex, and the frontal portion of the cerebrum is called the frontal lobe. Each cerebral hemisphere has a frontal lobe, as well as one of each of the other three lobes (they are not to be referenced in this post), and the two hemispheres are connected by what is called the corpus callosum ("tough body" in Latin), which allows the two hemispheres to share information with one another (see the below figure). The frontal lobe is responsible for planning movements, strategies, and things of that nature (all of which can be conscious processes), and the information the aforementioned nerves received from the heat source would have to be processed by the frontal lobe, and then processed back to the point of the sensation's origin before the finger would be retracted. But what exactly causes this process to become 'conscious?'
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| A visual of the cerebrum, its cortex, its hemispheres, and the corpus callosum. |
Neil R. Carlson's eleventh edition of his textbook The Physiology of Behaviour references a procedure known as the split-brain operation. This operation is performed on those afflicted with epilepsy so severe that it cannot be controlled with drugs. Epilepsy is a disorder in which the nerves of one of the cerebral hemispheres becomes overactive. Those nerves then process through the corpus callosum, and cause nerves in the other hemisphere to become overactive, resulting in what's known as a seizure. The purpose of the split-brain operation is to cut the corpus callosum, so that the overactive neurons cannot reach the other hemisphere. This prevents the hemispheres from taking part in interhemispheric communication, or the sharing of information and perceptions between hemispheres, as well as causes rather interesting side effects. In a case referenced by the same text, a post-op split-brain patient had been reading a book. The book was in the patient's left hand, and the holding of the book therefore correlated to the right side of the brain (connections to the brain are inverted, i.e. left hand to right hemisphere, etc.). In the brain of this patient, the right hemisphere could not interpret individual components of something, such as words to a text. Because the right cerebral hemisphere could not read what the book said, it became bored with it and caused the left hand to throw it away. When it was later discussed, the patient was not aware that the right hemisphere had decided to do so, and simply witnessed his own hand "having a mind of its own." In his textbook, Carlson has interpreted this as a region of the left cerebral hemisphere being involved in consciousness, and I would agree with this. However, I would further stipulate that it is not the only region of the cerebrum so involved, so much as any region besides the one from whence the communication originated.
For example, perhaps the frontal lobe is planning to contract the humerus, the long bone in the forearm. The individual is at first not aware of this, however becomes so when the frontal lobe communicates with one of the regions of the cerebral hemisphere, either ipsilateral (on the same side) or contralateral (on the other side) to it, that is responsible for associating vision, audition, or other sensory information with memories. At the point in which these two regions of the brain communicate, is the point at which the individual becomes aware of the frontal lobe's current activity. An analogy which might be employed to conceptualise this process would be two individuals who are having a conversation, and a third who is listening in. Equate one of the conversing individuals, individual A, to the frontal lobe, and the other individual, individual B, to the region to which the front lobe is communicating with. The third person (individual C) is the individual whose brain this is occurring in. Individual A is planning to buy a pizza to eat. Individual C is not yet aware of this because individual A has not shared this plan. When he shares it with individual B, individual B can help individual A figure out where to buy the pizza and how much it might cost. Individual C is not aware of how each of the individual are forming these ideas, however he has now become aware of the plan to buy the pizza due to his listening to the communication between individuals A and B. This is what I convict consciousness to be: the communication between different regions of the cerebrum, or perhaps between regions of the cerebrum and different areas of the brain in general.
In the paragraph previous to my analogy, I stipulated that the region of the cerebrum that did not communicate with the right hemisphere (due to the split-brain op) in the patient was not the only one involved in consciousness. Why? The patient was not aware of the right hemisphere's boredom with the book, nor was he aware of its plan to throw the book away, which was due to the procedure performed to cure his severe epilepsy. Would that then not mean that consciousness is isolated to only one hemisphere (left, in this case) of the brain? Not necessarily, otherwise how would the individual have made the decision to read the book in the first place? As I had mentioned previously, I convict the process of formulating plans and decisions is a subconscious one, and that this decision 'reflex' would cause the individual to become aware of it after the fact. My hypothesis would entail the region of the brain that received the communication from the frontal lobe about its plan to pickup the book caused the individual to become aware of it, however the region of the brain that was supposed to receive information from the frontal lobe of the right cerebral hemisphere about its boredom of reading the book had been disconnected due to the split-brain operation, thus preventing the individual from becoming aware of it.
This is but one of the many ideas I have concerning the brain and the nature of consciousness, and while I cannot yet ascertain whether or not there is truth in the concept of a 'decision reflex,' I deem it to be entirely plausible, and I look forward to being able to either prove or disprove myself in the future, when I have the means to.
References:
Carlson, Neil R. Physiology of Behavior. Boston: Allyn and Bacon, 2011. Print.
Harris, Sam. Free Will. New York: Free, 2012. Print.
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