In this week's reading I was really interested in how people without a corpus callosum would be able to make all of the same connections to the two different hemispheres as people with their corpus callosum. We all know that the corpus callosum in our brain is composed of nerve fibers in between the left and right hemispheres transferring information to either side. What would happen if there was no connector between the hemispheres? Would they even be able to make connections? How would the left side of the brain communicate with the right side without something in between the two? This was amazing to read that even though people who were born without a corpus callosum were slower and less accurate on tasks, although, they have some advantages as opposed to the split-brain people, or people who had surgery to their corpus callosum. This dangerous procedure has been helpful for those who experience epileptic seizures.
One example between split-brain patients and people with no corpus callosum is that split-brain patients cannot verbally describe what they feel since speech is mainly on the left hemisphere and the patient is looking in the left visual field but the information is coming from the right hemisphere. They are unable to make the connections with visual and verbal stimuli because the corpus callosum cannot transfer information across to the opposite hemisphere.
Another interesting fact about people born without a corpus callosum is that their brain learns to make other means of communication. For instance, commissures, or connectors, that are in the brain become larger so that those without a corpus callosum can have some type of communication between the two hemispheres. By doing so, this somewhat makes up for the loss of a corpus callosum.
This video of a split-brain patient named Joe, proves clearly that the right and left hemisphere have difficulties communicating with one anther. Dr. Gazzaniga explains why and how this occurs.
There are two types of strokes; ischemia and hemorrhage. The more common stroke is the ischemia which is an obstruction of a blood clot in an artery. Hemorrhage stroke is when an artery completely ruptures. There are many problems that come along with having a stroke such as edema, neurons dying, and an impaired sodium-potassium pump.
One of the main issues with ischemia stroke is the excess amount of the transmitter glutamate. Releasing a large amount of glutamate causes brain cells to die. There have been several studies as to how to prevent more damage to the brain after a stroke has occurred.
One study involves a famous plant, cannabis, to be a candidate to help alleviate pain, inflammation, and to stop the flow of glutamate after an ischemia stroke. Since us humans, and animals, indeed have a receptor for the only active compound, out of ten compounds found in cannabis, known as tetrahydrocannabinol (THC) there is a possibility that this plant can help in some way to dissolve the pain or pressure after a stroke. It has been found in laboratory animals that cannabinoids do alter brain activity and can protect against damage. I really do not see a difference on how it can affect humans just as it affects these lab animals.
The article I found about the role of cannabinoids after an ischemia stroke goes more into detail on how exactly the compounds of this plant work together with the brain receptors and the various positive outcomes that may follow.
I was personally fascinated with the Addiction
section in module 3.3. Why do or how can people become addicted to such drugs
or habits? The text explains that each individual builds a tolerance to the
dangerous or disadvantageous activity that makes a person crave more and act on
their craving. Researchers explain that people create an addiction as a way to
deal with stress. The addiction may take over one’s life therefore causing that
person to not have a reaction to a positive stimuli as a non-addict would. The
drug one takes or the habit one has releases the “feel good” chemical, dopamine, in the
brain released by the nucleus accumbens. When a large amount of
dopamine is present between different neurons, the excess amount stays in the
synaptic cleft which is between the presynaptic neuron and the postsynaptic
neuron. The video provided by Dr. Benham indeed gave a great visual of how
addictive drugs affect the neurons in the brain.
Along with having a tolerance to certain drugs or
activities such as video game playing, there come consequences including
withdrawal symptoms when one decides to quit. These symptoms vary widely
according to the type of drug used over time and the amount used during that
time. It has been said that addiction is built up to avoid these withdrawal
symptoms but that cannot explain the reason why people actually do become
addicted to drugs.
I was very interested how people can get cravings
in response to different cues. For example when an ex-smoker sees or smells a
lit cigarette, they will remember the effects it gave them and crave that feeling
of smoking once again. Cues also have a lot to deal with the place the drug was used, and remembering the feeling it gave off when on that drug.
This fun video I found explains the functions of
dopamine and serotonin in the brain and how addiction is developed.
I was very interested in the section of the text where it talked about the cells of the nervous system; especially the glial cells. The first thing that caught my attention was that there are many more glial cells than neurons in the brain. The video about glial cells or "genius cells" provided by Professor Benham, was very interesting how he explained the connection between glia cells and intelligence. The glia or neuroglia are what hold the neurons together. In the video, the neuroscientist explained that Einstein did not have more cells or neurons in his brain which made him more intelligent, but he did have more glia or glue holding neurons together than most people.
Another surprising fact that I found interesting was the different types of glial cells and their different functions. The astrocytes synchronize the activity of the axon which helps with sending messages. The microglia functions similarly to the immune system fighting off unwanted viruses and fungi. The oligodendrocytes work with the Schwann cells to create the myelin sheaths that surround the axon. The most interesting type of glia to me was the radial glial cells developing during the embryonic period and then forms into the oligodendrocytes and astrocytes later on in life. All of these types of glia have special functions, but all work together, that are vital to our nervous system.
I was intrigued by the difference between glial cells and neurons. As mentioned above, there are far more glial cells than neurons, however, the glial cells are much smaller than the neurons. The neurons are responsible for receiving messages and the glia protect and support the functions of neurons. It's interesting to read or hear how neurons communicate through electrical impulses but glial cells do not use electrodes to communicate with one another or with neurons.
I found a video where Neuroscientist Dr. Douglas Fields explains how there has not been much research done to figure everything out about the glia in our brain. However, I did like how he explains some differences between neurons and glia and how recent studies do show the connection between the two.
I chose this topic of comparing the intellect of men and women because several things stood out to me that caught my attention. I was surprised to learn that even though men do have a larger brain than women do, about ten percent larger, the intelligence quotient or IQ between them is relatively the same. However, there are way more differences that exist between the sexes such as social cognition, emotional stimuli, and many behavioral and biological differences. What I found most interesting was the actual physiology of the brain, the gray and white matter. The book explains that both male and female brains have about the same amount of neurons or gray matter but they are organized differently. My question is how much of a difference is there in organization between the brain of men and women? If they can accomplish the same tasks and is structured the same as well, what kind of physiological difference causes the way that these human brains function and categorize things.
This video kind of gave me a visual as to how the brains of men and women are organized differently. Mark Gungor explains how mens' brains are made up of "boxes" and everything is kept separate and the brain of the women is all connected by "wires". This is how women can remember most things and care about things that men would not care about or remember.
