Lesson 6 Flashcards
What is fMRI - functional magnetic resonance imaging)
brain scanning technique that measures blood flow and oxygen in the brain.
if brain area is more active there is an inc demand for oxygen in that area. brain responds by inc blood flow to that area. This is known as a hemodynamic response.
researchers are then able to produce maps showing which areas of the brain are involved in a certain mental activity.
fMRI creates a dynamic 3D image of the brain
What are strengths of fMRI
- it is non invasive does not involve the insertion of instruments in the body nor does it expose the brain to potentially harmful radiation.
- more reliable measure of psychological processes than verbal reports as well as objective.
- allows us to investigate cognitive mental processes that cannot be described through verbal reports.
- produces images that have a very high spatial resolution depicting very small details and provides a clear picture of how brain activity is localised.
what are some limitations of fMRIs
- it is expensive
- can only capture image if person is completely still.
- only measures blood flow in the brain - not a direct measure of neural activity in certain brain areas. not a quantitative measure of mental activity in these areas of the brain.
- criticised for overlooking the nature of brain activity only focuses on localised activity.
What is an EEG - electroencephalogram
- works on the idea that info is passed in the brain as electrical activity in the form of electrical impulses (action potentials) transmitted along neurons.
- measured through electrodes attached to the scalp.
- small electrical charges are detected by electrodes and are graphed over a period, indicating the general electrical activity of the brain.
- often used by clinicians as a diagnostic tool as arrhythmic patterns which indicate neurological abnormalities e.g. sleep disorders or tumours.
strengths of EEGs
high temporal resolution - provides a recording of brain activity in real time. researcher can accurately measure a particular task which the brain activity associated with it.
useful in clinical diagnosis - recording abnormal neural activity associated with epilepsy. seizures are caused by disturbed brain activity, which means a normal EEG reading suddenly changes.
limitations of EEGs
EEG can only detect activity in superficial regions of the brain, it cannot reveal what is going on in the deeper regions.
electrical activity can be picked up by several neighboring electrodes therefore the EEG signal is not useful in pinpointing the exact source of an activity.
many people describe the electrodes as being uncomfy.
What is ERP (event - related potential)
they use electrodes attached to the scalp.
a stimulus is presented to the ppt for eg a picture or a sound and the researcher looks for activity related to that stimulus.
the stimulus is presented many times usually hundreds which is graphed to separate it from the background EEG data.
this procedure is called averaging which reduces any extraneous neural activity which makes the specific response to the stimulus stand out.
strengths of ERPs
limitations of EEGs are combated by the usage of ERPs they bring more specificity to the measurement of neural processes.
high temporal resolution - activity is measured in real time.
limitations of ERPs
ERP is uncomfy for the ppt, as electrodes are attached to the scalp. This could result in unrepresentative readings as the patient’s discomfort may be affecting cognitive responses to situations.
hard to establish pure data in ERP studies, background noise and extraneous material must be eliminated and this is not always easy to do.
What is post - mortem examination?
post mortems are used to establish the underlying neurobiology of a behaviour.
this is a technique which involves the analysis of a person’s brain following their death.
in psychological research, researchers examine their brains to look for abnormalities that might explain a particular behaviour.
strengths of post - mortem explanations
- very important in giving a foundation to understand key processes in the brain.
- Broca and Wernicke both relied on this method to establish links between language and brain behaviours long before neuroimaging techniques were developed.
- improve medical understanding and help in the generation of hypotheses for further research.
- allow for more detailed examination of anatomical and neurochemical aspects of the brain, enables researchers to examine deeper regions.
limitations of post - mortem examinations
- people die in variety of circumstances at varying stages of disease and these factors can influence post - mortem studies.
- approach is limited as the person is dead, cannot follow up on anything that arises due to the post - mortem concerning a possible relationship between brain abnormalities and cognitive functioning.
