Biopsych -> Studying The Brain Flashcards
Post-Mortem Examinations
Psychologists may study a person who displays an interesting behaviour while they are alive. When the person dies, the psychologists look for abnormalities in the brain that might explain their behaviour. Post-mortem studies have found a link between brain abnormalities and psychiatric disorders, for instance, there is evidence of reduced glial cells in the frontal lobe of patients with depression.
Functional Magnetic Resonance Imaging
fMRI provides an indirect measure of neural activity. It uses magnetic fields and radio waves to monitor blood flow in the brain. It measures the change in the energy released by haemoglobin, reflecting activity of the brain (oxygen consumption) to give a moving picture of the brain; activity in regions of interest can be compared during a base line task and during a specific activity.
Electroencephalogram
EEG directly measures general neural activity in the brain, usually linked to states such as sleep and arousal. Electrodes are placed on the scalp and detect neuronal activity directly below where they are placed; differing numbers of electrodes can be used depending on focus of the research. When electrical signals from the different electrodes are graphed over a period of time, the resulting representation is called an EEG pattern. EEG patterns of patients with epilepsy show spikes of electrical activity. EEG patterns of those with brain injury show a slowing of electrical activity.
Event-Related Potentials
Electrodes are placed on the scalp and DIRECTLY measure neural activity (below where they are placed) in response to a SPECIFIC stimulus introduced by the researcher. Event-related potentials are difficult to pick out from all the other electrical activity being generated within the brain. To establish a specific response to a target stimulus requires many presentations of this stimulus and the responses are then averaged together. Any extraneous neural activity that is not related to the specific stimulus will not occur consistently
Strength of post-mortems
Detailed examination
Examine deeper regions
Weakness of post-mortems
Lack validity
Length of time from death & drugs
&
Small sample size
Difficult to generalise
Strength of fMRI
Dynamic brain activity
&
Good spatial resolution
Weaknesses of fMRI
Interpretation is complex
Poor temporal resolution
&
Expensive
Reduced sample sizes
Strength of EEG
Clinical diagnosis - Seizures
Weakness of EEG
Poor spatial resolution
Strength of ERP
Cheaper than fMRI
&
Good temporal resolution
Weaknesses of ERP
Poor spatial resolution
&
Cannot record activity deep in the brain
