brain scan techniques Flashcards
what is functional magnetic resonance imaging (fMRI)?
method used to measure brain activity while person performing task
detects changes in blood oxygenation and flow that occur as a result of neural activity in specific brain areas
active brain areas consume more oxygen- blood flow directed
produces activation maps showing which areas involved in certain processes
helps understand localisation of function
strengths of fMRI
doesn’t rely on use of radiation (unlike PET)
virtually risk-free, non-invasive and straightforward to use
produces images with high spatial revolution
strengths- safely provides clear picture of brain activity and localisation
limitations of fMRI
expensive
poor temporal resolution (5 second lag between neuron firing and image)
limitations- may not truly represent moment-to-moment brain activity, less accessible
what is electroencephalogram (EEG)?
measures electrical activity within brain via electrodes fixed to skull using skull cap
scan recording represents brainwave patterns- provides account of overall brain activity
diagnostic tool- can identify arrhythmic patterns of activity, may indicate neurological abnormalities e.g. epilepsy
strengths of EEGs
useful in studying sleep stages and diagnosing conditions like epilepsy
extremely high temporal resolution (accurately detects brain activity at res of a millisecond)
strengths- usefulness in real-world
limitations of EEGs
generalised nature of info received
doesn’t pinpoint exact source of neural activity
researchers can’t distinguish between activities originating in diff but adjacent locations
what are event-related potentials (ERPs)?
the electrophysiological response of brain to a specific sensory, cognitive or motor event can be isolated through statistical analysis of EEG data
filters out all extraneous brain activity from original EEG recording- leaving ERPs
ERPs- types of brainwave triggered by particular events
strengths of ERPs
bring more specificity to measurement of neural processes then raw EEG data
excellent temporal resolution
frequently used to measure cog functions and deficits e.g. maintenance of working memory
strengths- improves EEG data, practical real life applications
limitations of ERPs
lack of standardisation in ERP methodology between diff research studies- difficult to confirm findings
in order to establish pure data, all extraneous material must be completely eliminated- not easy to achieve
limitations- less straightforward and supported than other techniques
what are post-mortem examinations?
the analysis of a person’s brain following their death to determine whether certain observed behaviours during lifetime can be linked to structural abnormalities in brain
may also be compared to neurotypical brain to assess extent of difference
strengths of post-mortem examinations
provided foundation for understanding of key brain processes
e.g. Broca and Wernicke both relied on technique
strengths- historical value, provided info still useful today
limitations of post-mortem examinations
causation- observed damage to brain may not be linked to deficits under review but to some other unrelated trauma/decay
ethical issues of consent- participants may not have provided informed consent
limitations- challenges usefulness of technique
