ways of studing the brain Flashcards
scanning and other techniques
often used for medical purposes in the diagnosis of illness
purpose of scanning in psychological research is often to investigate localisation to determine which parts of the brain are doing what
functional magnetic resonance imaging
fMRI
works by detecting the changes in both blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain
when a brian area is more active it consumes more oxygen and to meet this increased demand blood flow is directed to the active area (haemodynamic response)
fMRI produces three-dimensional images (activation maps)
showing which parts of the brain are involved in particular mental process
had important implications for out understanding of localisation of function
electroencephalogram
EEG
measures electrical activity within the brian via electrodes that are fixed to an individuals scalp using a skull cap
the scan recording represents the brainwave patterns that are generated from the action of thousands of neurons providing an overall account of brain activity
EGG is often used by clinicians as a diagnostic tool as unusual arrhytmatic patterns of activity
may indiciate neurological abnormalities such as epilepsy tumours or some sleep disorders
Event-related potentials
although EEG has many scientific and clinical applications in its raw form it is a crude and overly general measure of brian activity
within EEG stat are contained all the neural responses associated with specific sensory cognitive and motor events that may be of interest to cognitive neuroscientists
research’s have developed a way of teasing out and isolating these responses
using a static ila averaging technique all extraneous brain activity from the original EEG recording is filtered out
leaving only those response that relate to the presentation to specific stimulus or performance of a specific task
what remains are event related potential (ERP)
types of brainwaves that are triggered by particular events \
research has revealed many different forms of ERP and how they are linked to cognitive processes such as attention and perception
post-mortem examinations
involving the analysis of a persons brian following their death
in psychological research individuals whose brain are subject to post-mortimer examination are likely to be those who have a rare disorder and have experienced unusal deficits in cognitive 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 brain in order to ascertain the extent of the difference
fMRI - strengths
unlike other scanning techniques such as PET it does not rely on the use of radiation
if administered corrrectly it is virtually risk-free, non-invasive and straightforward to use
also produces images that have very high spatial resolution depicting detail by the millimetre and providing a clear picture of how brian activity is localised
means that fMRI can safely provide a clear picture of brain activity
fMRI - limitation
fMRI is expensive compared to other neuroimaging techniques
poor temporal resolution because there is around a 5-second time lag behind the image on screen and th initial firing of neural activity
this means fMRI may not truly represent moment-to-moment brain activity
EEG- strengths
useful in studying the stages of sleep
and diagnosis of conditions such as epilepsy and disorder characterised by random bursts of activity in the brain that can easily be detected on screen
unlike fMRI EEG technology has extremely high temporal resolution of a single millisecond and even less in some cases
shows the real-worlds usefulness of the technique
EEG- limitations
generalised nature of the information received (that of many thousands of neurons)
EEG signal is also not useful for pinpointing the exact source of neural activity
does not allow researchers to distinguish between activities originating in different but adjacent locations
ERP- strengths
ERPs bring much more specificity to the measurement of neural processes than could ever be achieved using raw EEG data
as erps are derived from EEG measurements they have excellent temporal resolutions especially when compared to neuroimaging techniques such as fMRI
means that ERPs are frequently used to measure cognitive function and deficits such as the allocation of attentional resources and the maintained of working memory
ERP - limitations
critics have pointed to a lack of standardisation is ERP methodology between different research studies which make sit difficult to confirm findings
further issues is that in order to establish pure data in ERP studied background noise and extraneous material must be completely elimanted
this is a problem because it may not always be easy to achieve
ERP - limitations
critics have pointed to a lack of standardisation is ERP methodology between different research studies which make sit difficult to confirm findings
further issues is that in order to establish pure data in ERP studied background noise and extraneous material must be completely elimanted
this is a problem because it may not always be easy to achieve
post-mortem examinations - strengths
post-mortem evidence was vital in providing a foundation for early understanding of key processes in the brian
Broca and Wernickes both relied on post-morgen studied in establishing links between language brain and behaviour decades before neuroimaging
post-mortem studied were also used to study HMs brian to identify the areas of damage which could then be associated with his memory deficits
means post-morton’s continue to provide useful information
post-morgen examinations - limitations
causation is an issue within these studies
observed damage to the brain may nt be linked to the deficits under review but to some other unrelated trauma or decay
further problem is that post-mortem studies raise ethical issues of consent from the individual before death
participants may not be able to provide informed consent for example in the case of HM who lost his ability to orem memories was not able to provide such consent
challenged the usefulness of post-morgen studies
