Brain scans Flashcards
What are the 4 types of brain scanning techniques
- Post mortem examinations
- fMRI scans
- Electoroencephalogram (EEG)
- Event-related potentials (ERP)
Post-mortem examinations
analysis of a dead person brain
* mainly used to study people with rare disorders/ experience of unusual deficits in mental processes/behaviour during their lifetime
* when person dies, researchers can examine their brains to look for abnormalities in that behaviour, in comparison to individuals with neurotypical behaviour
* e.g. Brocas work with Tan
Broca and Tan
- Broca was interested in brain areas involving language and therefore studied patients with language impairments
- Tan suffered from brain damage that resulted in him only being able to say ‘tan’
- he could understand speech, follow instructions clearly and understand what was spoken
- when he died, Broca performed an autopsy and found substantial damage in the frontal lobe of the left hemisphere
- Broca concluded that an area in the left hemisphere, Brocas area was respnsible for speech productiob
Evaluation of post-mortem exam
- used during origins of psychology
- real world application
- cannot establish cause and effect
- lacks informed consent
used during origins of psychology
- post mortem examinations were vital during the early days of psychology before technology was developed
- e.g. Broca and Wernicke both relied on this brain scan when trying to establish links between the brain and language
real world application
post mortem examinations help improve medical knowledge and provides a greater understanding of rare afflictions in individuals
cannot establish cause and effect
cause and effect is a problem - the differences can be observed, unrelated to the behaviour
Lacks informed consent
some patients lose the ability to consent during their lifetime and sometimes it can be problemativ getting it from relatives (as its needed quickly.
therefore, it an ethical issue, but the longer it takes to get a brain for the postmortem exam, the less effective the results.
Evaluation
- Safer
- Good quality
- Cost
- Poor temporal resolution
- fMRI scans
Functional magnetic resonance imaging
* measure of blood flow through the concentration of oxygen in the bloodstream
* blood flow to active areas of brain are high due to an increased supply of oxygen in that area
* radio waves and magnetic field
* maps are produced showing areas of the brain that are involved in a particular mental activity
safer
unlike other scans (e.g. PET scans) it doesnt rely on the use of a radioactive tracer. its safe and non-invasive
good quality
it produced high resolution images that are accurate to the mm so its objevtive and reliable
it provides detailed knowledge of areas of the brain that are active whilst completing tasks
Cost
its expensive compared to other imaging techniques and requires equipment and trained experts
it also requires the patient to stay completely still
poor temporal resoluton
fMRI is an indirect measure of functioning. it studies blood flow rather than the actual firing of neurons. as such, theres a 5 second delay between neuron fiiring and and activity being detected. this means that what you see isnt quite in real time.
- EEG
Electroencephalogram
* measures electrical activity in brain via electrodes placed on scalp using skull cap
* scan records brainwave patterns generated from neurons to show brain activity
* data can be used to detect various types of brain disoreders such as epilepsy or Alzheimers disease e.g. reading of patients with epilepsy shows spikes of electrical activity
* patterns in pratients with brain disease and injury show an overall slowing of electrical activity
