ways of studying the brain Flashcards
functional magnetic resonance imaging (fMRI) definition
a method used to measure brain activity while a person is performing a task. fMRI detects radio waves from changing magnetic fields. This enables researchers to detect which regions of the brain are rich in oxygen and thus are active
Electroencephalogram (EEG) defintion
a record of the tiny electrical impulses produced by the brain’s activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain
Event-related potentials (ERPs) definition
the electrophysical response of the brain to a specific sensory, cognitive, or motor event can be isolated through statistical analysis of EEG data
Post-mortem examinations definition
the brain is analysed after death to determine whether certain observed behaviours during the person’s lifetime can be linked to structural abnormalities in the brain
why are scanning techniques used
investigating the brain and are used for diagnosis of illness. also to investigate localisation (determine what parts of the brain do what)
what does fMRI stand for
Functional magnetic resonance imaging
how does fMRI work
detecting the changes in both blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain. this is because when an area is more active, it consumes more oxygen, to meet the increase of demand in oxygen blood flow is directed into the active area –> called the haemodynamic response
what type of image does fMRI produce
3D called activation maps
what do activation maps show (fMRI)
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 does EEG stand for
electroencephalogram
how does EEG work
measures electrical activity within the brain via electrodes that are fixed to an individuals scalp using a skull cup. they can recording represents the brainwave patterns that are generated from the action of thousands of neurons, providing an overall account of brain activity
what is EEG often used for
used by clinicians as a diagnostic tool as unusual patters of activity (no particular rhythm) may indicate neurological abnormalities such as epilepsy, tumours or some sleep disorders
what does ERP stand for
event related potential
why is ERP used
raw from of EEG is a crude an general measure of brain activity. however, within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists
how have ERPs been developed
as a way of teasing out an isolating responses from EEG. a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to such as the presentation of a specific stimulus or performance of a specific task
what are ERPs
types of brainwave that are triggered by particular events. research has revealed many different forms of ERP and how for example, these are linked to cognitive process such as attention and perception
what does post-mortem examinations involve
analysis of a persons brain following their death.
who is post-mortem examinations used on
those who have a rare disorder and have experienced unusual deficits in cognitive processes or behvaiour during their lifetime
why can post-mortem examinations be used
as a means of establishing the likely case of affiliation the person experienced. this may also involve neurotypical brain in order to ascertain the extent of the difference
strengths of fMRI
-does not relay on radiation unlike other scanning techniques such as PET. if administered correctly it is virtually risk-free, non-invasive and straightforward to use.
-produces images that have very high spatial resolution, depicting detail by the millimetre, and providing a clear picture of how brain activity is localised –> means it can provide a clear picture of the brain
limitations of fMRI
-expensive compared to the other neuroimaging techniques
-poor temporal resolution because there is around a 5 second lag time behind the image on the screen and the initial firing of neural activity. –> means fMRI may not truly represent moment-to -moment brain activity
limitations of EEG
-generalised nature of the information received (of many thousands of neurons). the EEG signal is not useful for pinpointing the exact source of neural activity –> does not allow researchers to distinguish between activities originating in different but adject locations
strengths of EEG
-has been useful I studying the stages of sleep and in the diagnosis of such condition such as epilepsy, a disorder by random bursts of activity in the brain that can easily detected on the screen
-has an extremely high temporal temporal resolution
-todays EEG technology can accurately detect brain activity at a resolution of a single millisecond (and even less in come cases) –> shows real-world usefulness of the technique
strengths of ERPs
-brings much more specificity to the measurement of neural processes that can not be done with just EEG data
-as derived from EEG measurements they have excellent temporal resolution, especially compared to neuroimaging techniques such as fMRI. means they are frequently used to measure cognitive functions and deficits such as allocation of attentional resources and maintenance of working memory
limitations of ERPs
-lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings
-to establish pure data all extraneous variables such as background noise have to be eliminated, this is not always easy to achieve
strengths of post-mortem examinations
-was vital in providing a foundation for early understanding of key processes in the brain. Broca and Wernicke both relied on post mortem studies to establish links between language, brain and behaviour decades before neuroimaging became a possibility
-used to study HM brain and identify areas of damage which could then be associated with his memory deficits –> can provide useful information
limitations of post-mortem examinations
-causation can be an issue as observed damage to the brain may not be caused by the deficits under review but by some other form of trauma or decay
-ethical issues as participants may not be able to give informed consent, such as in the example of HM who lost ability to form memories and therefore could not give consent –> can challenge the usefulness of post-mortem studies in psychological research
