Ways of studying the brain Flashcards
Spatial resolution
Spatial resolution is the degree of accuracy that a technique achieves when examining brain activity. It is the accuracy with which the exact areas of brain structures and activity are identified.
Temporal resolution
Temporal resolution is the degree of accuracy in determining brain activity over time that the technique provides. It relates to when the activity virtually occurred and how accurately the technique can record this information.
What is a post Mortem?
Technique involving the analysis of a person’s brain following their death
Areas of the brain are examined to establish the likely cause of a deficit or disorder that the person experienced in life e.g trauma
This may also involve comparison with a neurotypical brain in order to assess the extent of the difference
What area was discovered using post mortem?
Broca’s areas (responsible for language production) - patient called Tan, who could only say Tan (expressive aphasia).
Damage in an area of the frontal lobe was found after Tans death
EVALUATION:
The high spatial resolution of post mortem allows…
the study of microscopic brain structures down to the neuronal level
EVALUATION:
As post mortem is not conducted on the living brain, unusual behaviour in life and damage found is correlational. However…
theories are then generated that can be tested with other, experimental techniques
EVALUATION:
Post mortem techniques have been significant in the historical development of…
psychology’s understanding of brain functioning such as the discover of language centres
EVALUATION:
Strength of post mortems - post mortems are used in localisation and medical research
Limitation of post mortems - knowing causation and ethics
Broca and Wernicke both relied on post mortem studies. Used to link HM’S memory deficits to damage in his brain - continue to provide useful info
Observed damage in brain may not be linked to deficits under review. They raise ethical issues of consent after death - challenges usefulness in psychological research
What does fMRI stand for?
Functional magnetic resonance imaging
What is a fMRI?
HIGHLIGHTS ACTIVE AREAS OF THE BRAIN
Detects changes in both blood oxygenation and flow that occur due to neural activity in specific brain areas
When a brain area is more active it consumes more oxygen and blood flow is directed to the active area (haemodynamic response)
fMRI produces a 3DS image - shows parts of the brain are active - must be involved in particular mental processes
EVALUATION:
fMRI has good spatial resolution of approx 1mm. Precisely identifying…
active brain regions and patterns of activation over time while participants complete experimental conditions
EVALUATION:
fMRI is non invasive and…
a safe technique for experiments compared to options that use radiation i.e PET scanners
EVALUATION:
Poor temporal resolution as one image is taken…
fMRI machines are expensive to…
every few seconds and delay blood flow after activity. This means many brain processes like vision are too fast to study
build and operate. Also as the participant needs to be still, experiments with body movement are not possible
What does EEG stand for?
Electroencephalogram
What is an EEG?
SHOWS OVERALL ELECTRIC ACTIVITY
It measure electrical activity within the brain via electrodes using a skull cap
Scan recording represents the brainwave pattern generated from thousands of neurons - showing overall brain activity
Often used as a diagnostic tool - unusual arrthymic patterns of the brain activity -> indicate abnormalities such as epilepsy, tumours/ sleep disorders
EVALUATION:
Historically important in understanding brain activity in areas such as…
sleep research and medical diagnosis
EVALUATION:
Cheaper than alternatives such as fMRI and…
able to be used in experiments in which the participant moves
EVALUATION:
Poor spatial activity as…
pattern is sum of a large number of neurons in the cortex under the electrode. So it is difficult to know exact source of neural activity - cannot distinguish activity of different but adjacent neurons
Also cannot detect activity deep within the brain
What does ERP stand for?
Event related potentials
What is an ERP
BRAINWAVES RELATED TO PARTICULAR EVENTS
Event-related potentials (ERPs) are very similar to EEGs because they also use electrodes and record the tiny electrical changes in the neurons of the brain.
The difference is that researchers present participants with a stimulus many times, and each wave response is added to a pool of data.
This creates a smooth activation curve of the collected data, called statistical averaging
EVALUATION:
ERP’s allow researchers to…
isolate and study how individual cognitive processes take place in the brain, while EEG’s record general brain activity
EVALUATION:
Like EEG’s, ERP’s have good temporal (compared to fMRI) - resolution with a millisecond sampling rate - freq used in cognitive research BUT…
very poor spatial resolution. Some processes cannot be studies studied by ERP as they cannot be presented a large number of times with the same response
EVALUATION:
Limitation of ERP’s - lack of standardisation and background ‘noise’
Lack of standardisation makes it difficult to confirm findings in studies involving ERPs - background noise and extraneous material must be completely eliminated - these issues are a problem, may not always be easy to achieve
