L9- Studying the brain Flashcards
what are post-mortem examinations and what has been found?
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. -
what has been found from post-mortem studies?
-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.
evaluation of post-mortem examinations? (strength)
Post-mortem studies allow for more detailed examination of anatomical and neurochemical aspects of the brain that wouldn’t be possible with other methods of studying the brain.
-They have enabled researchers to examine deeper regions, such as the hippocampusand hypothalamus.
evaluation of post-mortem examinations? (weakness)
Studies using post-mortems may lack validity due to small sample size (requires special permission) and because people die in a variety of circumstances and at varying stages of disease.
-Similarly, the length of time between death and the post-mortem, and drug treatments, can all affect the brain.
explain functional magnetic resonance imaging.
(fMRI) 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.
evaluation of fMRI
+ fMRI captures dynamic brain activity as opposed to anMRI/post-mortem examination which purely show the physiology of the brain.
- Interpretation of fMRI is complex and is affected by temporal resolution, biased interpretation, and by the baseline task used.
- fMRI research is expensive leading to reduced sample sizes which negatively impact the validity of the research
explain the use of an electroencephalogram.
(EEG) measures GENERAL electrical 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.
evaluation of EEG
+ An EEG is useful in clinical diagnosis, for instance it can record the neural activity associated with epilepsy so that doctors can confirm the person is experiencing seizures.
+They are cheaper than an fMRI so can be used more widely in research.
-EEGs have poor spatial resolution(refers to the smallest feature that a measurement can detect).
explain event-related potentials. (ERP)
Electrodes are placed on the scalp and detect neuronal activity (directly below placement) in response to a SPECIFIC stimulus introduced by the researcher.
- Event-related potentials are difficult to pick out from all the other electrical activity in the brain.
- To establish a specific response the target stimulus requires many presentations and the responses are averaged together.
- Any extraneous neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will.
what are sensory and cognitive ERP’s?
sensory - ERP waves generated in the first 100milliseconds after the stimulus is presented. they reflect the initial response to the physical characteristics of the stimulus.
cognitive- ERPs generated after first 100mseconds. They reflect the manner in which the patient evaluates the stimulus and demonstrate information processing
Evaluation of ERP
+ ERP can measure the processing of a stimulus even in the absence of a behavioural response. Therefore it is possible to measure ‘covertly’ the processing of a stimulus.
- Only sufficiently strong voltage changes generated across the scalp are recordable. Important electrical activity occurring deeper in the brain is not recorded. The generation of ERPs tends to be restricted to the neocortex.
