Biopsychology: Ways of study the brain Flashcards
What is fMRI? (Functional magnetic resonance imaging)
A technique used for measuring blood flow in brain when a person performs a task
How does fMRI measure brain activity?
It works by detecting changes in blood flow that indicate increased neural activity.
How does fMRI measure blood flow?
Using radio waves and a magnetic field - magnetic field used bc oxygenated and deoxygenated blood have different magnetic qualities.
What happens if an area of the brain becomes more active?
Area more active = increased demand for oxygen in that area, bc brain uses oxygen when carrying out functions.
Brain responds by increasing blood flow, delivering oxygen in RBC’s.
Maps showing which areas of the brain are involved in a particular neural activity are produced as a result of blood flow.
Spatial resolution
smallest measurement a scanner can detect
Temporal resolution
how quickly scanner detects changes in brain activity
Advantage of fMRI - high res images
Produces high res images (accurate to a mm) so clear image of where functions are localised
Disadvantage of fMRI - poor temporal res
Poor temporal resolution because there is a 5 second time-lag behind the image on the screen and the initial firing of neuronal activity.
Worse than other techniques (EEG/ERP which have temporal res. of 1-10 milliseconds)
Consequently, psychologists unable to predict to a high degree of accuracy the onset of brain activity
Advantage of fMRI - non-invasive
Non-invasive
Unlike, PET scans, fMRI doesn’t use radiation or involve inserting instruments directly into the brain, therefore virtually risk free
Consequently, allows more patients to undertake fMRI scans
Could help psychologists gather further data on the functioning of the human brain
Therefore, develops understanding of localisation of function.
Disadvantage of fMRI - costs
Expensive compared to other imaging techniques – requires equipment and trained experts
Post-mortem examinations
Researchers study an individual’s brain post-death who displayed a behaviour which suggested possible underlying brain damage when alive
Post-mortem advantage
Vital during the early days of psychology before technology was developed e.g Broca and Wernicke
Post-mortem disadvantage - cause and effect
Cause and effect is an issue; the differences observed can be unrelated to the behaviour, possibility of damage being cause by unrelated trauma or decay
Post-mortem disadvantage - unethical
Ethical issues of informed consent.
Patients may not be able to provide informed consent, e.g in the case of HM – he was unable to form new memories and was not able to provide consent.
EEG
measures patterns of electrical activity within the brain
How does an EEG work?
Electrodes placed on the scalp detect small electrical charges resulting from activity of brain cells.
Electrical signals from electrodes graphed over time represents an EEG
What are EEG’s used to detect?
Brain disorders e.g. Epilepsy
Disorders that influence brain activity such as Alzheimer’s.
What will an EEG pattern representing epilepsy show?
sudden spikes of electrical activity
What will an EEG pattern representing brain injury show?
overall slowing of brain activity.
EEG: 4 wave types
Alpha
Beta
Theta
Delta
What to waves show?
Frequency - speed/quantity of brain activity
Amplitude - intensity/size of brain activity
Why is an EEG used in sleep research?
Diff stages of sleep correspond to diff levels of brain activity
Light sleep =
Alpha waves
Deep sleep =
Delta and theta waves
Advantage of EEG - more readily available
Consequently, should allow more patients to undertake EEG/ERP
Help psychologists gather further data on the functioning human brain
Can develop understanding of diff psychological phenomena, such as sleeping and disorders like Alzheimer’s
Advantage of EEG - high temporal res.
Takes readings every millisecond
Can record the brain’s activity in real time as opposed to looking at a passive brain.
Therefore an accurate measurement of electrical activity when undertaking a specific task.
EEG disadvantage - uncomfortable experience.
Suggest why fMRI scans are better
Electrodes are attached to the scalp = uncomfortable
Unrepresentative readings as patient’s discomfort may affect cognitive responses to situations.
fMRI scans, on the other hand, are less invasive and would not cause the participants any discomfort, leading to potentially more accurate recordings
EEG disadvantage - Poor spatial res.
EEGs/ERPs only detect the activity in superficial regions of the brain.
Consequently, EEGs and ERPs are unable to provide information on what is happening in the deeper regions of the brain (such as the hypothalamus)
Makes technique limited in comparison to the fMRI, which has a spatial resolution of 1-2mm.
Which brain scanning technique has the best spatial res?
fMRI - 1-2mm
Which brain scanning technique(s) has the best temporal res.?
EEG and ERP
ERP
similar to EEG but involves a stimulus & researcher looks or activity related to that stimulus.
EEG disadvantage - general measure
Activity of many neurons is picked up, as the signal from an individual neuron is not strong enough to detect
What does an ERP show?
The brains electrophysiological response to a specific sensory, cognitive, or motor event that can be isolated through statistical analysis of EEG data.
ERP procedure
Electrodes are places on a persons head to measure electrical impulses from the brain .
A stimulus is presented to a participant and the researcher looks for activity related to that stimulus
Why are statistical averaging techniques used in ERP’s?
all extraneous brain activity from the original EEG recording is filtered out
Leaves responses linked to a specific stimulus
How is ‘noise’ reduced in an ERP
Reduces ‘noise’ (other activities in brain) by presenting stimulus repeatedly to participant
