Studying the Brain (A2 only)
Psychology: AQA A Level, topic 6.1.8
Functional Magnetic Resonance Images (fMRI)
Functional magnetic resonance images (fMRIs) are useful in the study of both structure and function of the brain.
MRI scanners
- In magnetic resonance imaging (MRI), a person is placed inside a machine that generates a strong magnetic field.
- The magnetic field causes the hydrogen atoms in the body’s cells to move.
- When the magnetic field is turned off, the hydrogen atoms emit electromagnetic signals as they return to their original positions.
- Tissues of different densities give off different signals, which a computer interprets and displays on a monitor.
FMRIs
- Like all cells, brain cells require glucose and oxygen to function.
- fMRIs, through the use of radio waves and magnetic fields, detect changes in the levels of oxygen in the blood as the oxygenated blood responds differently.
- Areas of the brain that are more active require more oxygenated blood; therefore can be identified by the fMRI.
Advantage
- An advantage of fMRI is good spatial resolution, meaning it can detect differences in structure and function in different areas of the brain.
- For example, fMRI can distinguish within the millimetre range.
Disadvantage
- A disadvantage of fMRI is poor temporal resolution, meaning it cannot detect changes in brain activity over time.
- Other disadvantages include high running cost and patients have to sit still for long periods of time in an enclosed space.
Electroencephalograms (EEG)
Technology has provided new insight into the structure, activity and function of the brain. The techniques of ERPs, EEGs and fMRIs have proved useful in studying localisation of brain function.
Method
- Electroencephalograms (EEG) are useful in the study of overall brain activity.
- A patient is hooked up to an EEG.
- Electrodes are placed on the scalp of the patient and this records brain activity.
- Wave patterns are generated.
- Different patterns are going to result from different stimuli.
Sleep studies
- These are often used in sleep studies, comparing brain activity during the different stages of sleep.
- Generally, different wave patterns are created.
Advantage - high temporal resolution
- An advantage of EEGs is that they have high temporal resolution, meaning they show changes in brain activity over time well.
- Subtle differences across seconds can be recorded and provide valuable information.
Disadvantage - poor spatial resolution
- A disadvantage of EEGs is that they have poor spatial resolution, meaning they do not show brain activity of specific areas, only overall brain wave activity.
Event-Related Potential (ERP)
Technology has provided new insight into the structure, activity and function of the brain. The techniques of ERPs, EEGs and fMRIs have proved useful in studying localisation of brain function.
ERP
- An event-related potential (ERP) is electrical activity in the brain generated as result of stimuli.
- An electroencephalogram (EEG) is used to study these wave patterns.
Wave patterns
- Biopsychologists can compare normal wave patterns to the patterns that are caused by external stimuli.
- Different wave patterns are generated in response to different stimuli.
Example - P3 wave
- For example, a P3 wave is produced as a result of decision making and processing novel situations.
Test yourself on Studying the Brain (A2 only)
What does fMRIs stand for?
Within what range can FMRI distinguish?
What is a weakness of FMRIs?
Which is NOT a technique that has proved useful in studying localisation of brain function?
EEGs have high what?