Ways of Studying the Brain Flashcards
What is spatial resolution?
The capacity a technique has to tell you exactly which area of the brain is active
What is temporal resolution?
The ability to tell you exactly when the activation happened
What are post mortem examinations?
When a person’s physical brain is examined who displayed a particular behaviour that suggested possible brain damage. They try to correlate structural abnormalities with behavioural changes. In modern examinations, the brain can be sliced into sections and studied on a microscope.
What are the strengths of post mortem examinations?
Allows detailed observation of anatomical structure and neurochemical aspects of the brain that is not possible with non-invasive techniques.
Provides insight into deeper regions of the brain like the hypothalamus and hippocampus which other techniques cannot access.
What are the weaknesses of post mortem examinations?
Retrospective method so it may be hard to make comparisons with functioning before death.
Need for special permission leads to small sample size
Ethical issues as there are debates on whether patient would need to give consent before death, though patients with severe psychological deficits would be unable to give consent.
What is functional Magnetic Resonance Imaging?
An fMRI uses a strong magnetic field and radio waves to detect changes in blood oxygenation and flow in the brain as a result of neural activity. It takes repeated scans to form a dynamic image of concentration of blood in the brain at one time. Areas of high activity will have a high amount of blood concentration. This allows active sections of the brain to be identified.
What is a strength of fMRIs?
Provides moving picture of brain activity which is highly valuable when trying to link brain activity to key behaviours.
It is considered to be more ethical due to it being a non invasive scanning method.
It has a good spatial resolution of 1-2 mm, which allows scientists to discriminate between different areas of the brain.
What are the weaknesses of fMRIs?
Scans simply measure blood flow, so scientists are unable to conclude whether the brain region is associated with a particular function - we cannot establish cause and effect.
Poor temporal resolution of 1-4 seconds, meaning scientists are unable to predict with a high degree of accuracy the onset of brain activity.
What are Electroencephalograms?
EEGs work on the premise that information is processed in the brain as electrical activity in the form of action potentials. It uses electrodes fixed to a pts scalp which detect neuronal activity directly below where they are placed. It measures the amplitude and frequency of electrical activity and identifies patterns in activity that may be associated with certain states. Small electrical changes are graphed over a period of time.
What are the strengths of EEGs?
Can be used effectively in clinical practise to study sleep disorders, identify disturbed brain activity and help with diagnosis.
Good temporal resolution (1-10 ms) meaning it can record the brain’s activity in real time as opposed to looking at a passive brain
What are the weaknesses of EEGs?
Electrical activity can be picked up by neighbouring electrodes therefore it is not useful for pinpointing the exact source of activity.
Poor spatial resolution so it is unable to provide information on what is happening in deeper regions of the brain.
What are event related potentials?
Uses electrodes attached to the scalp and a stimulus is presented to the pt and the researcher looks for neuronal activity in response to that stimulus. It is necessary to take recordings from numerous presentations then average out the response. Often used when investigating fast responses that may not be detected by other investigative techniques.
What is a strength of ERPs?
Useful to measure the reliability of self reported techniques especially when the topic being investigated is sensitive and is affected by social desirability.
Good temporal resolution (1-10 ms) meaning it can look at the brain’s activity in real time rather than looking at a passive brain
What are the weaknesses of ERPs?
It only detects strong voltage changes across the scalp. Important electrical activity deep in the brain is not recorded, hence this method is limited to just the neocortex.
Poor spatial resolution so it is unable to provide information on what is happening in the deeper regions of the brain.
What are the similarities between fMRIs and EEGs?
Both are able to give fully informed consent.
Both are non invasive
Both are based on interpretation
Causation is not clear
