ways of investigating the brain Flashcards
1
Q
what are the 4 ways of investigating the brain
A
- post mortem
- fMRI
- EEG
- ERPs
2
Q
what are post mortem examinations
A
- used to establish the underlying neurobiology of a particular behaviour.
- researchers may study a person who displays an interesting behaviour while they’re alive that might suggest possible underlying brain damage.
- Subsequently, when the person dies, the researchers can examine their brains to look for abnormalities that might explain their behaviour.
3
Q
what are the +ve AO3 points for post mortem
A
Research Support:
- An early example of this technique was Broca’s work with his patient Tan
- Tan displayed speech problems when he was alive
- A post-mortem revealed a lesion in the area of the brain now known as ‘Broca’s area’; an area important for speech production.
- Vital during the early days of psychology before technology was developed. e.g Broca and Wernicke
- Enables us to improve medical knowledge
4
Q
what are the -ve AO3 points for post mortem
A
- Cause and effect is a problem because the differences observed can be unrelated to the behaviour.
- Zhou, Hofman and Gooren (1995) studied 6 people who had undergone a full sex change from male to female.
- They found that an area of the brain called the BSTc was “female sized” rather than male sized and therefore concluded that this brain abnormality had caused the gender dysphoria.
- However, we cannot prove that this is true - hormones taken to transition could have altered the size of the BSTc, hence illustrating issues with cause and effect sometimes made by post-mortem.
- Informed consent - some cultures/religions do not allow this procedure
5
Q
what are fMRI’s
A
- Functional magnetic resonance imaging
- measures changes in brain activity while a person performs a task.
- Measures changes in blood flow to particular areas of the brain
- This indicates increased neural activity in those areas.
- If a particular area of the brain becomes more active, there is an increased demand for oxygen in that area. The brain responds to this extra demand by increasing blood flow, delivering oxygen to the red blood cells
- As a result of these changes in blood flow, researchers are able to produce maps showing which areas of the brain are involved in a particular mental activity.
6
Q
what are the +ve AO3 points for fMRI’s
A
- Unlike other scans (such as PET Scans) it doesn’t rely on the use of a radioactive tracer. It’s risk free and non-invasive.
- High spatial resolution –> It produces high resolution images that are accurate to the millimetre so provides a clear image of where functions are localised.
7
Q
what are the -ve AO3 points for fMRI’s
A
- Expensive compared to other imaging techniques - requires equipment and trained experts (state of the art brand new machine is 2 million pounds)
- Requires patient to stay still for a clear image which wouldn’t be easy for patients with some conditions.
- Has poor temporal resolution –> fMRI is an indirect measure of functioning. It is studying blood flow rather than the actual firing of neurons so there is a 5 second delay between the neuron firing and activity being detected –> This means that what your seeing isn’t quite real time.
8
Q
what are EEG’s
A
- Electroencephalogram (EEGs)
- measures electrical activity in the brain.
- Electrodes placed on the scalp detect small electrical charges resulting from the activity of millions of neurons
- When electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG.
- This method provides an overall account of brain activity.
9
Q
what are the +ve AO3 points for EEG’s
A
- EEG data can be used to detect various types of brain disorder (such as epilepsy) or to diagnose other disorders that influence brain activity such as Alzheimer’s disease.
- E.g. readings of patients with epilepsy show spikes of electrical activity. EEG patterns in patients with brain disease and brain injury show overall slowing of electrical activity.
- High temporal resolution (as can detect activity in under one millisecond)
10
Q
what are the -ve AO3 points for EEG’s
A
- Poor spatial resolution does not enable us to work out which specific parts of the brain are malfunctioning
- It is only a general measure - not exact like fMRI –> the signal from an individual neuron is not strong enough to detect so only indicates a general area where many neurons are firing.
11
Q
what are ERPs
A
- Event Related Potentials (ERPS)
- Although EEG has many clinical and scientific applications, in its raw form it is too crude and general.
- However within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists.
- As such researchers have devised a way of teasing out and isolating these responses using a statistical averaging technique.
- All extraneous brain activity from the original EEG is filtered out leaving only the responses that relate to the presentation of a specific stimulus or performance of a specific task.
- What remains are event related potentials: types of brainwave that are triggered by particular events.
- Research has revealed many different forms of ERP and how these are linked to various disorders
12
Q
what are the +ve AO3 points for ERPs
A
- ERP abnormalities in clinical research have been shown in neurological conditions such as:
- Dementia
- Parkinson’s disease
- multiple sclerosis
- head injuries
- Stroke
- OCD
- More specific than raw EEG readings.
- Excellent temporal resolution
13
Q
what are the -ve AO3 points for ERPs
A
- Differing procedures have been adopted (not standardised so difficult to compare and replicate the findings of studies using this technique)
- To be successful all extraneous interference (e.g. noise) needs to be eliminated and this is hard to achieve
