Ways Of Investigating The Brain Flashcards
How does fMRI work
Detects changes in blood oxygenation and flow that result of neural activity in specific parts of the brain, when certain brain area more active it consumes more oxygen to meet increased demand and blood flow directed to this area
What does fMRI produce
3D images showing which parts of the brain are involved in a particular mental process, can help understand localisation of function
Strengths of fMRI
-does not rely on use of radiation and is non invasive and straightforward to use
-produces images with high spatial resolution, depicting detail by the millimetre= provides clear picture of how brain activity localised
Weaknesses of fMRI
-expensive compared to other neuroimaging techniques
-can only capture clear image if person stays perfectly still
-poor temporal resolution as there is 5 sec time lag behind the image on screen and firing of neuronal activity
-can only measure blood flow in the brain and cannot home in on activity of individual neurons=can be difficult to tell exactly what kind of brain activity is being represented on screen
How does EEG work
Measure electrical activity within the brain via electrodes that are fixed to scalp using skull cap
-the scan recording represents brainwave patterns generated from the action of millions of neurons= account of overall brain activity
When are EEGs often used
By clinicians as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities eg epilepsy/tumours
Strengths of EEG
-invaluable in the diagnosis of conditions eg epilepsy
-contributed much to our understanding of the stages involved in sleep
-extremely high temporal resolution unlike fMRI, at resolution of a single millisecond
Weakness of EEG
-generalised nature of the info received (of many thousands on neurons), signal not useful for pinpointing exact source of neural activity and does not allow researchers to distinguish between activities originating in dif but adjacent locations
-unable to provide info on what is happening in deeper regions of brain
What are event-related potentials (ERPs)
The brain’s electro physiological response to a specific sensory/cognitive/motor event that can be isolated through statistical analysis of EEG data, all extraneous brain activity from og EEG recording filtered out leaving only those responses that relate to specific stimulus presented
Strengths of event-related potentials
-bring much more specificity to the measurement of neural processes compared with raw EEG data
-excellent temporal resolution= led to their use in the measurement of cognitive functions and deficits
-researchers been able to identify precise role of ERPs in cognitive functioning
Weaknesses of event-related potentials
-pack of standardisation in ERP methodology between dif research studies makes it difficult to confirm findings
-in order to establish pure data background noise and extraneous material must be completely eliminated
What are post-mortem examinations
Brain analysed after death to determine whether certain observed behaviours during patient’s lifetime can be linked to abnormalities in the brain.
-likely to be patients who have rate disorder during lifetime, can examine areas of damage within the brain as means of establishing likely cause of the affliction the person experienced, may involve comparison with neurotypical brain to ascertain extent of the dif
Strengths of post-mortems
-vital in providing foundation for early understanding of key processes in the brain eg Broca and Wernicke both relied on post-mortem studies before neuroimaging became a possibility
-improve medical knowledge and help generate hypotheses for further study
-can access areas eg hypothalamus and hippocampus which other scanning techniques cannot= insight into deeper brain regions
Weaknesses of post-mortems
-observed damage to the brain may not be linked to the deficits under review but other unrelated trauma/decay= cannot conclude causation
-ethical issues of consent from individuals before death eg HM lost his ability to form memories so was not able to provide informed consent but post-mortem research has been conducted on his brain
