Source: image of impaled skull: PD-1923; http://en.wikipedia.org/wiki/File:Phineas_gage_-_1868_skull_diagram.jpg EEG; Public Domain http://commons.wikimedia.org/wiki/File:EEG_early_studies_edited.jpg
Hello class. So today we're going to be focusing a bit more on the brain itself as the central part of the nervous system. Now, the brain is responsible for everything that makes up a person's thoughts, feelings, perceptions, language, and behaviors. So it allows for the full range of the human experience. So how have psychologist determined the different functions of the brain themselves, like where and how these mental processes happen? Well, we're going to examine this a bit more in detail in this lesson.
So through various types of studies, psychologists have determined that certain areas and structures of the brain relate to certain behaviors or mental processes. And this is what we call localization of functions, so specific areas lead to certain functions. And these are regular areas in most people. However, it's important to note that the brain is very complex. So sometimes it's difficult to point to exact areas or neurons.
So we have to only go with general areas to understand that relate to certain kinds of functions. So one area of the brain is generally related to let's say vision, but we wouldn't necessarily say that one specific neuron would lead to one function of vision. That would be difficult to determine because of its complexity. Also, the brain is very adaptable. It adapts to different situations and different responses from the environment. This is what we call neuroplasticity, which is the ability of the brain to change in response to the environment or to different kinds of events that occur in life.
So the brain is constantly growing and developing and making new connections within the neurons normally over time, especially when we're younger, but throughout our entire lifespan. So for example, in terms of neuroplasticity, a stroke victim might have damage to a specific area of the brain. And now because of that localization of function, certain types of things that they might try to do would also be impaired. So they might have some problems with movement with speech with things like that.
But over time, because of neuroplasticity and the ability of the brain to adapt in these kinds of ways, stroke victims have been shown to regain some of those functions over time. This is because the area surrounding those damaged parts of the brain will start to take on some of those different functions. So the brain is changing in some small ways to adapt. Now some stroke victims might not completely regain all of their function, but they might regain some of it over time. That shows that adaptability of the brain. So it's important to remember when we talk about these different functions.
Now historically, localization of function has been studied in brain damaged patients. So we've been studying the loss of certain abilities that a person might have, things like movement like we said, and then finding out which areas of the brain's we're damaged. So we're going backwards historically with a lot of these. Now these have been studied in people that are alive in the example of one Phineas Gage who was a famous psychological subject, who had a tamping rod shot through his frontal lobe of his brain. He survived.
But there is damage to a specific part of his brain. And they found that there was a change in his mood and his personality. He essentially became a different sort of person. And this helped psychologists to understand that part of the brain that was damage was related to personality and mood. And all those sorts of things that make a person who they are. So that could be one way that localization of function is studied.
Another way is after somebody has died, so post mortem patients that have reported certain kinds of problems. For example, if somebody has trouble producing speech, then they can have their brains examined after they've died to find out where those areas are that have received some kind of damage. For example, in people that have lost speech famously have been examined and found to have a certain area of the brain that was damaged which was later determined to be called the Broca's area, which is related to the production of speech itself. So those are different ways we can discover the functioning of the brain.
Now to further study the localization of functions of the brain, we can actually look at healthy patients as well. So remember neurons communicate through electrical impulses. So providing electrical stimulation directly to certain parts of the brain can activate them and show the results and the different functions of those specific parts of the brain. So surgically what somebody might do as a psychologist is to implant an electrode or replace an electrode, which is a device that produces an electrical stimulation to a certain area of the brain, and then measure those responses.
So in using electrodes on certain parts of the brain, we found that you can actually produce movements or aggression in people. Or you can have them start to remember certain memories, if you activate that area of the brain, speech, or even crying in different patients. So you can see it's a wide range of things that we can do with electrical stimulation.
We can also use powerful magnets to receive the same kinds of results, and this is something relatively new that's being developed through Transcranial Magnetic Stimulation or TMS. That might be something interesting for you to research on your own. Alternatively, you can measure the electrical activity of the brain to see which areas are being active. And this can be done through the head instead of having to do surgery.
And this is through the use of an electroencephalograph or EEG, which is a device that's placed on a person's head that can amplify and measure those electrical responses of the brain to show which specific areas are being activated. So if you get a person to perform a certain kind of behavior that you want to measure, for example, reading, what you can do is use the EEG and see which one of those areas is being activated. And so you can show how that area is producing those thoughts or behaviors. And you can also measure to see which areas are being damaged in certain patients, which can help in the treatment of those patients.
Providing electrical shocks directly to certain parts of brain to activate them and measuring responses.
A device placed on a person’s head that can amplify and measure the brain’s electrical activity.
The idea that specific areas and structures of the brain relate to certain behaviors or mental processes.