Nervous System Power Hour Reading

Name of Book: Mastermind: How to Think Like Sherlock Holmes by Maria Konnikova

Name of Chapter: The Scientific Method of the Mind

In this chapter, Konnikova discussed the method of deduction employed by Sherlock Holmes, and how we can apply it in our own lives. She claims that Holmes has trained himself to use the scientific method to evaluate his every thought and action- something that, to a normal person, sounds exhausting, but has become second nature to Holmes. Most of us are reactive, relying on instinct and simply responding to a situation. This book aims to teach us how to become reflective, just like Sherlock Holmes, and consider what we see before we respond.

This reading relates to ideas of neuroplasticity that we have been learning about. The idea that we can  alter our way of thinking simply by practicing shows that we really can create neural pathways and strengthen them through continual use, just as we learned from "A Woman Perpetually Falling"

A Woman Perpetually Falling

"A Woman Perpetually Falling" starts off by describing a woman who has no sense of balance, and therefore always feel like she's falling, even when lying down. She can't walk, can't even stay upright, without losing her balance and falling. Then, she begins working with Dr. Bach-y-Rita, who has designed a hat which acts as a temporary vestibular system (sense of balance). Surprisingly, when she takes off the hat, she retains that sense of balance for some amount of time- an amount of time that increases each time she uses the hat. Dr. Bach-y-Rita ascribes this to neuroplasticity, explaining that the brain is forming new pathways which grow stronger each time that she puts the hat on and uses the pathways. Neuroplasticity, though not a new concept, has only recently come to be accepted by the scientific community; previously, scientists believed that there was one and only one location in the brain for each function, ignoring any evidence to the contrary. However, as Bach-y-Rita discovered, the brain can often reorganize itself.
This was very interesting to me, especially because we have just been learning about functions of different parts of the brain in class. However, after reading through the article, I realized that those locations were probably where those functions are primarily associated with those locations, but could also take place in another part of the brain if necessary.

There were some quotes that stuck out to me in the reading. The first was that the hat, the machine that allowed the woman to recover her vestibular sense, helped "to reinforce the signals from her healthy tissues. He [Bach-y-Rita] thinks the machine also helps recruit other pathways." I thought this was interesting because the hat was such a simple device- it used electrodes on the tongue which told the woman which way she was leaning- and yet it had such dramatic effects on her brain.  The second quote that stood out to me was that localizationism "went from being as series of intriguing correlations (observations that damage to specific brain areas led to loss of specific mental functions) to a general theory that declared that every brain function had only one hardwired location." This was interesting because science is supposed to be open-minded and accepting of change, but this theory completely shut out the idea of neiroplasticity, even though the observations it was based on did not disprove the idea. I was also intrigued by an experiment in which a scientist rewired the optic nerves of ferrets to go to the auditory cortex. He found that the auditory cortex reorganized itself to process sight, and "though the ferrets that had this surgery did not have 20/20 vision, they had about a third of that, or 20/60- no worse than some people who wear eyeglasses." This implied that while a reorganized structure of the brain works, it doesn't work quite as well as the original structure, which would mean that although neuroplasticity clearly exists, the typical locations of specific functions are still important.

The Woman With a Hole in Her Brain

An article from New Scientist, called "Woman of 24 Found to Have No Cerebellum in Her Brain," describes the woman mentioned in the title and how her complete lack of a cerebellum- the center of language and motor control- affect her life. Surprisingly, this has relatively little effect on her. Although it took the woman until the age of six to learn to speak coherently, and couldn't walk until age seven, she seems to have very few lasting effects, other than moderate issues with motor control, such as having difficulty walking steadily. This was quite surprising to me, since the cerebellum has such an important role. It does make sense, however; when I was first learning about the structures of the brain, I wondered why there were so many parts that had overlapping functions, and those redundancies would be useful in situations like this one.

I also researched how a missing thalamus would affect someone. Hypothetically, that person would have little or no sensation, as the thalamus both controls sensation and connects other parts of the brain which are also involved in sensory perception. However, there is a man reported to be missing around fifty to seventy-five percent of his brain. This is reportedly due to the slow nature of his brain degeneration which allowed other structures to take over for the missing ones. This raises the question: could the functions of the thalamus be taken on by other structures of the brain? The truth is, we don't know.

Unit 5 Reflection

In this unit, we began by talking about the digestive system. We did a lab showing the length of our digestive tract, and the total length I ended up with was quite surprising. The digestive system has two main purposes: digestion and absorption. Food starts in the mouth, where it is broken down by saliva and teeth. It then goes down the esophagus into the stomach, where it is further digested using both contraction and gastric juices. The food goes into the small intestine, where absorption starts. The small intestine is composed of the duodenum, jejunum, and ileum. In the duodenum, more chemical digestion occurs, while the jejunum and ileum are primarily involved in absorption, and use microvilli to do so. Finally, the remaining indigestible food goes into the large intestine, where it is dried out and then excreted through the rectum.

Next, we talked about metabolism, or where nutrients go after they are absorbed by the small intestine. It turns out that there are actually three states of metabolism- the fed state, the fasting state, and the starving state. In the fed state, the body releases insulin, prompting the liver to store glucose, while amino and fatty acids are sent to the cells. About an hour after a meal, the body goes into the fasting state. Glucagon levels rise, and glucose stored in the liver is used. The body begins to rely more on fatty acids and ketone bodies. Finally, after four to five days of not eating, the body goes into the starvation state, where the body relies almost exclusively on ketone bodies for fuel.

In the next lesson, we learned about diabetes. Type one is an autoimmune disorder in which the body attacks the insulin-producing cells in the pancreas, leading the body to become insulin dependent, or unable to produce insulin, so they must inject it into themselves. This often begins in children, and it has a relatively quick onset. Type two diabetes is far more common. It usually appears in adults, and is caused by insulin resistance, meaning the cells no longer respond to insulin, either because excess fats in the blood block insulin receptors or because their fat is secreting a hormone preventing insulin from binding to its receptors. Both types of diabetes have terrible consequences if they are not managed properly.

The endocrine system also plays an important role in metabolism. This system consists of glands which secrete hormones of two types: steroid and nonsteroid. Steroid hormones are lipid soluble, and can therefore pass through cell membranes, binding to receptors inside the cell and affecting DNA. Nonsteroid hormones, however, react with receptors outside the cell, triggering a reaction and ultimately influencing functions inside the cell. Hormones are controlled through negative feedback- meaning they are turned on and off based on physical changes. The pituitary gland, which acts as the middle man between the hypothalamus and the rest of the body, consists of the posterior lobe, which produces ADH and oxytocin, and the anterior lobe, which produces  ACTH, GH, FSH, lutenizing hormone, and prolactin. The thyroid gland is in the middle of the neck, and it secretes T3, T4, and calcitonin, regulating metabolism and promoting glycolysis and gluconeogenesis. The parathyroid gland secretes PTH, which regulates phosphate levels and plasma calcium. The adrenal medulla secretes epinephrine and norepinephrine, which controls the fight or flight response, while the adrenal cortex secretes mineral corticoids, glucocorticoids, and gonadocorticoids. The pancreas produces insulin and glucagon to help with metabolism, and the kidneys regulate red blood cell production. Gonads control sex characteristics.

Finally, we learned about the lymphatic system, which helps with immunity, lipid absorption, and fluid recovery. Lymph vessels, which are filled with lymph,  travel through the body beside blood vessels. Lymph capillaries clean out the spaces between cells, then flow into the lymph vessels and eventually the lymph nodes, which filter the lymph. Lymph is pumped through vessels by rhythmic contractions. There are different types of lymphocytes in lymph nodes which fight pathogens- the T cells, which fight previously identified pathogens, B cells, which produce antibodies, and NK cells, which watch for pathogens. Some important lymph nodes are the thymus, which produces T cells; the tonsils, which fight inhaled pathogens; and the spleen, which regulates red blood cells and responds to pathogens in the blood.

This unit was a bit difficult because I had just transferred into this class, so I wasn't sure exactly what was expected of me, especially  with the journals, but I think I figured that out fairly quickly. Another difficulty I had was in not planning far enough in advance for this test. I did well at engaging in class and contributing to groups even though I was new to the class. 

I would still like to know what the difference between the lymphatic system and the immune system is, if there is any, as well as how the human digestive system has evolved to become what it is in our species, and what gut bacteria really do for you, other than make you fart. I would also like to know more about the circulatory system, as it seems very important to all of the systems we just learned about.

I think I have done pretty well on my New Year's Goals. I have been participating in class frequently, both in group and lecture settings, and paying attention. I did have a bit of trouble with planning out my assignments- I was a bit rushed on my elevator pitch, and I definitely should have started studying for this test earlier- but I think that I have been doing pretty well with my goals this unit. I will try to look on Canvas more frequently, though.