11. ways of studying the brain Flashcards
what is an electroencephalogram (EEG)
measures electrical activity within the brain via electrodes that are fixed to an individuals scalp using a skull cap.
the scan recording represents brainwave patterns that are generated from the action of millions of neurons providing an overall account of brain activity.
used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities - epilepsy or tumours.
what are the strengths of an electroencephalogram (EEG)
important in the diagnosis of conditions such as epilepsy. it has also contributed to much of our understanding of the stages involved in sleep.
unlike fMRI, EEG technology has extremely high temporal resolution.
today EEG technology can accurately detect brain activity at a resolution of a single millisecond.
what are the weaknesses of an electroencephalogram (EEG)
tends to produce very generalised information so it is not useful for pinpointing the exact source of neural activity.
does not allow researchers to distinguish between activities originating in different but adjacent locations of the brain.
what is functional magnetic resonance imaging (fMRI)
works by detecting the changes in blood oxygenation and flow that occur as a result of neural (brain) activity in specific parts of the brain.
when a brain area is more active it consumes more oxygen and to meet this increased demand, blood flow is directed to the active area.
MRI produces 3D images (activation maps) showing which parts of the brain are involved in a particular mental process and this has important implications for our understanding of localisation of function.
what are the strengths of functional magnetic resonance imaging (fMRI)
unlike other scanning techniques such as PET it does not rely on the use of radiation.
if administered correctly it is virtually risk-free, non-invasive and straightforward to use.
it also produces images that have very high spatial resolution depicting detail by the millimetre and providing a clear picture of how brain activity is localised.
what are the weaknesses of functional magnetic resonance imaging (fMRI)
expensive compared to other neuroimaging techniques and can only capture a clear image if the person stays perfectly still.
it has poor temporal resolution because there is around a 5 second time lag behind the image on screen and the initial firing of neuronal activity.
fMRI can only measure blood flow in the brain - cannot home in on the activity of individual neurons and so it can be difficult to tell exactly what kind of brain activity is being represented on screen.
what are event related potentials (ERP)
basic and general form of looking at brain activity - used as a way of teasing out and isolating specific neural responses associated with sensory, cognitive and motor events that may be of interest to cognitive neuroscientists.
works by using statistical averaging technique that filters out extraneous brain activity from the original EEG recording leaving only those responses that relate to the presentation of a specific stimulus or performance of a specific task.
researchers have shown different forms of ERPs linked to cognitive processes such as attention and perception.
what are the strengths of event related potentials (ERP)
the limitations of EEG are partly addressed through the use of ERPs - bring much more specificity to the measurement of neural processes than could ever be achieved using raw EEG data.
as ERP are derived from EEG measurements they have excellent temporal resolution especially when compared to neuroimaging techniques such as fMRI and this has led to their widespread use in the measurement of cognitive functions and deficits.
researchers have been able to identify many different types of ERP and describe the precise role of these in cognitive functioning including parts of the working memory.
what are the weaknesses of event related potentials (ERP)
critics have pointed to a lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings.
a further issue is that in order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated and this may not always be easy to achieve.
what are post mortem examinations
technique involving the analysis of a persons brain following their death.
in psychological research individuals whose brains are subject to a post mortem are likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime.
areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person experienced. this may also involve comparison with a neurotypical (healthy) brain in order to ascertain the extent of the difference.
what are the strengths of post mortem examinations
vital in providing a foundation for early understanding of key processes in the brain.
both broca and wernicke relied on post mortem studies in establishing links between language, brain and behaviour decades before neuroimaging ever became a possibility.
post mortem studies improve medical knowledge and help generate hypotheses for further study.
what are the weaknesses of post mortem examinations
causation is an issue within these investigations - observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay.
post-mortem studies raise ethical issues of consent from individuals before death. such individuals may not be able to provide informed consent - for example in the case of HM who lost his ability to form memories and was not able to provide such consent. nevertheless post mortem research has been conducted on his brain.
