Brain scanning techniques Flashcards
fMRI
Functional Magnetic Resonance Imaging.
oxygen, task
fMRI 2
- measures brain activity while a task is performed.
- uses MRI technology (detecting radio waves from changing magnetic fields)
- enables researchers to detect which regions are rich in oxygen (active) when involved in a particular mental activity.
part of the brain becomes more active, oxygen demand increases, increased blood flow to the brain, perceive areas activated by certain stimulus.
Pros of fMRI
- non invasive- no harmful radiation/ invasion with tools.
- objective/ reliable measure of psychological processes. useful in investigating psychological phenomena not present in verbal report.
Cons of fMRI
- not direct measure of neural activity in the brain. Not quantitative.
- ignores networked nature of brain- focuses on localisation.
EEG
Electroencephalogram.
EEG 2
- Measures electrical activity in the brain.
- electrodes placed on scalp detect small ECs from activity of brain cells.
- electrical signals graphed = EEG
Uses of EEGs
- To detect types of brain disorders (eg. epilepsy) or to diagnose disorders that influence brain activity (eg. Alzheimer’s)- from spikes of slowing of brain electricity.
Pros of EEG
- Records brain activity in real time, not a still image. More accurate measurement.
- useful in clinical diagnosis (epilepsy in someone experiencing seizures)
Cons of EEG
- cannot reveal deeper processes such as the hypothalamus (reaches superficial regions). Electrodes in non humans to achieve this = unethical.
- activity picked up by neighbouring electrodes- cannot pinpoint exact source. Cannot differentiate between close areas.
ERPs
Event- related potentials
In it’s raw form EEG is a general measure of brain activity- contained within the data is useful info about sensory, cognitive and motor events.
Isolates these responses through statistical averaging technique- where all activity filtered to leave responses relative to a stimulus.
ERP Pros
- addresses limitations of EEG- specificity of measurement of neural processes.
- derived from EEG measures = high temporal resolution, led to widespread use in measurement of cognitive functions and deficits.
ERP Cons
- lack of standardisation in ERP methodology between research studies, difficult to conform findings.
- background noise and extraneous material must be completely eradicated, may be challenging
Post mortem examination
- involves analysis of the brain following death- likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during life.
- areas of damage are examined to establish likely cause of the personal affliction.
- may involve comparison with neurotypical brain in order to ascertain the extent of difference.
Pros of post-mortem
- vital in providing a foundation for early understanding of key processes in the brain- Broca and Wernicke (before neuroimaging was possible)
Cons of post-mortem