Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.
Brain and Behavior
Brian loves brains. He's fascinated by how our brain can make us do things, even without our control. For example, every time he smells lavender, Brian's brain conjures memories of his Nana. He doesn't have to try to think about her; she just pops in his head!
Brian is a psychologist who studies how our brains influence our behavior. For example, one of his patients was in a bad car accident and hit the side of her head. As a result of the injury, she has trouble speaking and understanding what people are saying to her.
Psychologists, like Brian, are interested in how the brain works to guide human behavior. But it's a pretty complicated job! The human brain is not labeled. If Brian opened up his patient's head and looked at her brain, he wouldn't see a little sign that said, 'This section controls language,' or one that said, 'This section controls problem-solving.'
As a result, psychologists have to get a little creative to study the link between brain and behavior. Specifically, they look at how a person acts and what different parts of a person's brain are doing. Essentially, they create a link between observed behavior and observations of the person's brain.
Let's look closer at two techniques that Brian and psychologists like him can use to study the link between brain and behavior: imaging and pathology.
Brian is lucky that he lives in modern times because there are many ways to look at a person's brain without actually opening up his or her head. For example, let's say that he wants to take a look at his patient's brain to see what's going on that's affecting her language skills.
It used to be that Brian would only have one option to look at his patient's brain: to cut open her skull and look at it. Because this is a dangerous technique, this was usually done after the patient died. So, Brian would have learned about the brain in general but not learn how to help this particular patient.
But now, Brian has all sorts of brain imaging techniques that allow a doctor or psychologist to look at a person's brain without having to do surgery. There are several major brain imaging techniques.
EEG stands for electroencephalography, and it involves measuring electrical activity along the scalp of a person. The readout for an EEG session looks like a bunch of squiggly lines and allows Brian and others like him to see which general areas of the brain have the most going on. For example, he might do an EEG and see that his patient has very little activity on the left side of her brain. That might help him understand that her problems spring from some sort of damage to that area.
2. PET and CAT scans
A PET scan is a positron emission tomography, which takes an image of activity in the brain by tracing small amounts of radioactive matter that are injected into a person, and a CAT scan is a computed axial tomography, which is essentially a 3-dimensional X-ray of a person's brain. Sometimes, these two things are combined together.
PET and CAT scans used to be the normal way for psychologists, like Brian, to look at their patients' brains. But they are not used as much anymore because there are better techniques to measure brain activity.
3. MRI and fMRI
MRI stands for magnetic resonance imaging, and fMRI stands for functional magnetic resonance imaging. An MRI looks at the structure of a person's brain, like a CAT scan. Like a PET scan, an fMRI measures brain activity. But instead of having to inject a person with radioactive material, an MRI uses magnetic waves to measure brain activity. Remember 'magnet' and 'image', and you'll understand how magnetic resonance imaging uses magnets to produce an image of what areas of a person's brain are active.
Diffusion tensor imaging is still pretty new, but it's becoming more and more popular. Whereas an fMRI looks at brain activity on the surface of the brain, DTI examines the deep-down white matter of the brain, which links areas of the brain to one another.
If all that sounds confusing to you, don't stress out. Remember that all of these methods, from EEG to DTI, are doing the same thing: they are trying to look at brain activity to see how it affects a person's behavior.
Sometimes, psychologists, like Brian, look at a bunch of healthy people's brain scans to figure out how a healthy brain works. For example, Brian might put a bunch of people in an MRI machine and ask them to read words or answer questions while he scans their brain to get an fMRI image. He might notice that almost all of them have increased activity on the left side of the brain while doing these activities, which would tell him that the language centers of the brain are on the left side.
But sometimes, psychologists instead study a person's pathology, or disease or other issue. For example, remember that Brian has a patient who has trouble speaking and understanding. He could study her brain and figure out that she has damage on the left side of her brain. He might then conclude that the language centers of her brain are on the left side of that brain.
Historically, psychologists looked at the pathology of a person only by examining their brains during autopsy. For example, Brian knows that his patient has problems with language. After she died, he could remove and examine her brain to see where the damage to the brain was.
This is still a major part of research, but now, with brain imaging and more advanced surgical procedures, Brian and other psychologists like him can look at a person's brain while they are still alive, and in many cases, while they are still awake.
Regardless of when he examines his patient, the basic idea is that Brian can either study people with healthy brains or people with pathological brains. Either way, he's trying to get at the answer to the question, 'How does the brain influence this specific behavior?'
Many psychologists are interested in studying the way the brain influences a person's behavior. Brain imaging allows a scientist to see an image of brain activity and comes in many forms, like EEG, which measures electrical activity; PET and CAT scans, which measure activity in a brain through tracing radioactive chemicals and/or taking 3-D X-rays; MRI and fMRI, which measure activity on the surface of the brain using magnets; and DTI, which measures activity in the white matter of the brain. Regardless of the technique, a psychologist can either examine the brain of healthy individuals or that of individuals with a pathology to better understand the link between brain and behavior.
After you have finished with this lesson, you should be able to:
- Identify the importance of studying the link between the brain and behavior
- Describe four types of imaging to study the brain and how each works
- Explain how psychologists can use pathology to understand the link between the brain and behavior
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