Techniques Used to Study The Brain Flashcards
What are the four techniques to study the brain?
- Post mortem examinations
- Functional magnetic resonance imaging (fMRIs)
- Electroencephalograms (EEGs)
- Event - related potentials (ERPs)
What is a post mortem examination?
An analysis of the brain after the person has died
When are post mortem examinations mainly used?
Post mortem examinations are mainly used to study people who display a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime
In post mortem examinations, areas of the damaged brain are examined. Why does this happen?
Areas of damage in the brain are examined as a means of establishing the likely cause of death
What can post mortem examination potentially involve?
Post mortem examinations may involve comparison with neurotypical brains to ascertain the extent of difference
What is an example of post mortem examinations?
An example of this work was Broca and his patient Tan, which lead to the discovery that the Broca’s area was responsible for speech
What is the full story of Tan?
This patient suffered brain damage that resulted in him only saying the word “tan”. He understood speech clearly and followed instructions. Broca performed an autopsy on Tan’s brain and found substantial damage to an area towards the base of the frontal lobe in the left hemisphere.
What were Broca’s conclusions from assessing Tan’s brain?
Broca concluded that this area of the left hemisphere, now known as Broca’s area was responsible for speech production.
What is a strength of post mortem examinations? (foundation of learning brain processes)
Post - mortem evidence was vital for providing a foundation for early understanding of key processes in the brain. Broca and Wernicke both relied on post mortem studies in establishing links between language, brain and behaviour decades before neuroimaging became a possibility. Post - mortem studies improve medical knowledge and help generate hypotheses for further study
What is functional magnetic resonance imaging (fMRIs)?
This technique measures blood flow through the concentration of oxygen in the bloodstream
What is a limitation of post mortem examinations? (cause and effect)
In post mortem examinations, establishing cause and effect is a problem. The observed differences can be unrelated to the behaviour. Another problem is that post mortem studies raise ethical issues of consent from individuals before death. Such individuals may not be able to give informed consent
Why do fMRIs use the concentration of oxygen in the bloodstream to measure blood flow?
Blood flow to active areas of the brain should be high because there is an increased demand for oxygen in the area. As a result the brain responds to this demand by increasing blood flow, delivering oxygen in the red blood cells
How is blood flow measured by fMRIs?
Blood flow is measured by radio waves and magnetic fields
How do researchers show the mental activity in the brain?
Researchers are able to produce maps showing which areas of the brain are involved in a particular mental activity
What is a strength of functional magnetic resonance imaging (fMRIs)? (less risk and harm)
Unlike other scans (such as PET scans) fMRIs do not rely on the use of a radioactive tracer. Additionally, administered correctly, fMRIs are virtually risk free, non invasive and straightforward to use. Minimising risk and harm to patients.
What is a strength of functional magnetic resonance imaging (fMRIs)? (images produced)
Functional magnetic resonance imaging produces images that have a very high spatial resolution, depicting detail by the millimetre and providing a clear picture of how brain activity is localised.
What is a limitation of functional magnetic resonance imaging (fMRIs)? (cost + quality)
Functional magnetic resonance imaging proves more expensive to use, compared to other neuroimaging techniques. It can only capture. Additionally, it’s cost does not reflects it quality as a clear image can only be captured if a person stay completely still
What is a limitation of functional magnetic resonance imaging (fMRIs)?
Functional magnetic resonance imaging are arguably an indirect measure of functioning. This technique studies the blood flow rather than the actual firing of neurons. Due to this, there is a 5 second delay between the neuron firing and activity being detected. As a result, it could be stated, there is poor temporal resolution
What is a electroencephalogram (EEG)?
A technique that measures electrical activity in the brain via electrodes that are placed on the scalp using a skull cap
What can electroencephalogram (EEG) data be used to detect?
EEG data can be used to detect various types of brain disorders such as epilepsy or Alzheimer’s disease
What information does this technique record?
The electroencephalogram record brainwave patterns generated from neurons to show brain activity
What is a strength of electroencephalograms (EEGs)? (detects range of issue)
EEGs have been extremely useful in investigating a wide range of issues including sleep and in detecting epilepsy. This technique allows medics to act quicker in diagnosis and aid in patient treatment
What is a strength of electroencephalograms (EEGs)? (temporal resolution)
EEGs have high temporal resolution as they can detect activity in under one millisecond
What is a limitation of electroencephalograms (EEGs)? (signal detection)
EEGs receive signals to operate, this signal from an individual neuron is not strong enough to detect so it only indicates areas when many neurons are firing. This is not useful for studying cognitive functions such as memory, attention or perception
What are event related potentials? (ERPs)
Event related potentials use the same equipment as EEGs, measuring electrical activity in the brain through electrodes placed on the scalp using a skull cap
Why are event related potentials described as being too general?
Event related potentials have many scientific and clinical applications, but are simply too general. This is because researchers filter out all extraneous brain activity to study types of brainwave that are triggered by particular events
How do event related potentials work?
Event related potentials filter out all extraneous brasin activity to study types of brainwave that are triggered by particular events. A participant would is asked to respond to specific stimuli then the researcher will be able to cancel out to background activity by finding an area that is consistently active
What is a strength of event related potentials? (ERPs) (specificity)
Event related potentials are more specific than raw electroencephalograms readings so this allows researchers to pinpoint the localisation of function
What is a limitation of event related potentials? (ERPs)
Event related potentials take a lot of time and effort to operate and gather results from
What is a limitation of event related potentials? (ERPs)
Event related potentials require elimination of any other background noise, which makes it harder for the researcher to use because eliminating all types of noise is hard to doe
