biopsychology-ways of studying the brain Flashcards
what is temporal resolution
precision of out measurements with respect to time
what is spatial resolution
Level of detail at which our methods allow us to examine the brain
what is a post-mortem examination
also know as an autopsy
what is the aim of a post-mortem
to determine the cause of death
what is an post-mortem
dissect the brain into thin slices and examine under a microscope
what is a strengths of post mortem examination
One strength is that they allow us to look at people’s brains at a high level of detail to identify small brain abnormalities which relate the behaviour the patient displayed whilst they were alive
what are 3 weaknesses of post-mortem
-post-mortem examinations require specialist permission to be conducted which often leads to small sample sizes
–One weakness is that we don’t know when the brain abnormality occurred making it difficult to establish a cause and effect relationship.
-It is hard to control confounding, or extraneous variables, like medication, which might also affect the patients’ brains.
what does an EEG do
uses electrodes fixed to a participants scalp
what do electrodes measure
electrodes measure the activity if the cells immediately under the electrode
what does the scan recording represent
brainwave patterns it gives the overall account of brain activity
why are EEGs used by clinicians as a diagnostic tool
arrhythmic patterns may indicate neurological abnormalities eg-epilespsy
what are the 4 basic EEG patterns
alpha, beta, delta and theta
what happens if peaks and troughs are close together
-high frequency which shows a high level of activity
what happens if peaks and troughs are more spaced out
low frequency which shows a lower level of activity
what is a strength associated with EEGs
(sleep disorders)
useful in diagnois of condtions eg-epilespsy as they are charcateristed by random bursts of activity in the brain
they have also helped use understand stages of sleep/sleep disorders
what is a strength associated with EEGs
(resolution)
high temporal resolution-brain activity is measured in real time researcher can measure a particular task with the brain activity associated with it
what is a strength associated with EEGs
(cheaper)
cheaper method than scanning so are widely available to researchers
what is a strength associated with EEGs
(safe)
safe as there no surgery/ invasive procedures
what is a limitation associated with EEGs
not useful for pinpointing the exact source of neural activity as it has poor spacial resolution. It only detects activity in superficial regions of the brain and not deeper regions due to the multitude of tissues the electric current passes through
what apparatus do ERPs use
same as EEGs
what type of activity to ERPs record
record events in response to a stimulus introduced by the researcher
how do ERPs isolate events related to a specific stimulus
using statistical averaging techniques all extraneous activity from the original EEG recording is filtered out leaving only responses that relate to a specific stimulus
what are the responses relating to a specific task/ stimulus know as
event related potentials type of brainwave triggered by a particular event
what are waves occurring within the first 100 milliseconds knows as
sensory ERPs-reflect an initial response to a stimulus
what are waves occurring after the first 100 milliseconds knows as
congnitive ERPs-demonstrate information processing + manner which particpent evaluates the stimulus
what is a strength of ERPs
(specific)
ERPs bring a higher specificity to the measure of neural processes
what is a strength of ERPs
(resolution)
high temporal resolution which has led to their widespread use in the measurement of cognitive functions
what is a weakness of ERPs
(standardisation)
lack of standardisation in ERP methodology makes it difficult to conform findings
what is a weakness of ERPs
(large number of trials)
extranreous varibales must be completely eliminated so ERPs are therefore small
what is a weakness of ERPs
(deep)
don’t measure electrical activity from deep within the brain
difference between EEGs and ERPs
EEGs-general recording of brain activity linked to stats such as sleep and arousal
ERPs-elecited to specific stimuli presented by the particpant
what occurs when different areas of the brain are active
when areas of the brain are active they consume more oxygen and to meet this increased demand blood flow increases to the active area
what is passed over the brain
a strong magnetic field is passed over the brain. The magnet tracks the oxygenated blood, when this oxygen is transferred to brain tissue a tiny magnetic change occurs. This is picked up by the scanner and turned into an image
what type of image does an fMRI give
dynamic (moving) image.
shows activity 1s after it occurs
accurate within 1-2 mm
active sections show up at brightly coloured splotches
strength of fMRI
(dynamic)
due to the dynamic nature of the fMRI patterns of activity can measured rather than the physiology of the brain
strength of fMRI
(radiation)
Does not rely on radiation, non-invasive and straight forward. This means it can be done on pregnant women and children
High spacial resolution giving a clear picture about how brain activity is localised
weakness of fMRI
(time delay)
it has a poor temporal resolution because there’s a 5 second time delay this makes it difficult to interpret the fMRI scans
weakness of fMRI
(activity)
fMRI measures chnages in blood flow rather than individual neural actvivity
weakness of fMRI
(expensive)
fMRI machines are expensive to buy and maintain so require specialised operators
weakness of fMRI
(setting)
takes place in an artificial setting which lowers ecological validity. This means behaviour may differ to everyday life
