Functional Magnetic Resonance Imaging (fMRI)
fMRIs are a modification of a regular MRI machine. Whereas MRIs simply show the structure of the brain, fMRIs can record ongoing brain activity. They are also more accurate and display results in a higher resolution than PET scans. They are very common in a range of modern neuropsychological research studies.
So how do they work? When the brain performs a task (like playing the piano, thinking, looking at pictures, etc.) neurons are “activated”. As you should already know, different areas of the brain have different functions. So with each task a particular part of the brain is functioning. This means that those neurons are “firing” and neurotransmission is occurring in that area of the brain. During this neurotransmission, there is an increased blood flow between the neurons. The fMRI uses magnetic fields and radio waves to detect these changes in blood flow in the brain.
The fMRI can project on the computer which parts of the brain have the increased blood flow, which allows researchers to see which parts of the brain are functioning during different tasks. Different colours show the different levels of activation in areas of the brain.
What happens in an fMRI?
When researchers are using an fMRI they ask participants to lay in the machine and perform certain tasks. Often there is a screen that appears in the fMRI and it has the relevant information that the participants use to complete the task the researchers are asking of them. There is also a hand held remote that has various buttons, one of these being the button they can push if they want to stop the process.
In one study the researchers investigated what was happening in the brains of people who were in love when they saw images of their loved one. While the participant was lying in the fMRI machine, they showed each participant a photo of the person they were in love with, and then showed a picture of an acquaintance. The results showed that different areas of the brain were activated depending on the person the subject was looking at. A part of the brain involved in motivation (the VTA) with high levels of dopamine was activated when the subject saw their “beloved”. The researchers were able to use the fMRI in this study to investigate the relationship between the brain, love, and motivation.
fMRIs are often used in research investigating the biological factors affected in people with psychological disorders. One study compared war-vetereans who had been diagnosed with PTSD and war-veterans who did not have PTSD (the control group). They flashed images of happy face and angry faces while in the fMRI and the participants simply had to look at the photographs and the fMRI recorded what areas of the brain were activated. The results showed that in the PTSD subjects, there was an increase in activation in the amygdala when seeing the angry faces. There was also less activity in their frontal lobes than in the control groups. The amygdala is known to have a role in processing emotional memories and the frontal lobe helps to control our behaviour and our emotional impulses. Other research studies using fMRI have also shown a correlation between a hyper-responsive amygdala, reduced activity in the frontal cortex and PTSD symptoms.
So does this mean that a hyper-responsive amygdala may be the cause of PTSD symptoms? If you can answer this question you will have figured out a major limitation in using fMRI in psychological research.
Examples of Research using fMRI:
- Dopamine and Romantic Love (See Key Study Description)
- PTSD and fMRI studies (see above)
- Mirror Neurons (Course Companion, p48)
- What correlation does an fMRI show?
- fMRIs measure “dynamic rather than static” information. What does this mean?
- What are the strengths and limitations of using an fMRI?
- What is the relationship between brain activity and behaviour as shown in the results of one study using fMRI?
Extension Critical Thinking Questions
- How did one study use an fMRI to investigate (and demonstrate) relationships between the brain and behaviour? (Application)
- What are the fundamental differences between an MRI and an fMRI? (Analysis)
- What are the strengths and limitations of using fMRIs to investigate relationships between the brain and our behaviour? (Evaluation)
Hannibal, Jette. Crane, John. Psychology. Course Companion. Oxford Press. UK. 2009
Law, Alan et al. Psychology: Developed Specifically for the IB Diploma. 2010.
Here’s another video that shows an excerpt from a longer video about emotional memory and the use of fMRI to investigate them. This will give you a good insight into how fMRI works.
If you need some more info, here’s a good introduction to fMRIs:[youtube=http://www.youtube.com/watch?v=BmQR57V5TVU&w=420&h=315]