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techniques for investigating the brain - Coggle Diagram
techniques for investigating the brain
scanning and other techniques
functional magnetic resonance imagine
fMRI
works by detecting changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain
when a brain is more active in one area, it consumes more oxygen and to meet this demand, blood flow is directed to the active area (haemodynamic response)
produces 3 dimensional images showing which parts of the brain are involved in particular mental processes which has important implications for our understanding of localisation of function
EEG
measure electrical activity within the brain 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 actions of millions of neurons, providing an overall account of brain activity
often used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities such as epilepsy, tumours or sleep disorders
scanning and other techniques
ERP
within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events
researchers developed a way of teasing out and isolating these responses
using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to the presentation of a specific stimulus or performance of a specific task
what remains are event related potentials - types of brainwaves that are triggered by particular events
post mortem examinations
examination of persons brain after death
likely to be those who have a rare disorder and have experienced unusual deficits in their lifetime
areas of damage within the brain are examined after death as means of establishing the likely cause of the affliction the person suffered
may involve a comparison with a neurotypical brain in order to ascertain the extent of the difference
evaluation
fMRI
strength
- 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, giving a very clear picture of how brain activity is localised.
weakness
- it is expensive compared to other techniques and can only capture a clear image if the person is completely still. it has poor temporal resolution because there is a 5 second time lag behind the image on the screen and the initial firing of neuronal activity, also difficult to tell what kind of brain activity is being represented as it can only measure blood flow not individual neuron activity
EEG
strength
- has proved invaluable in diagnosis of conditions such as epilepsy. it has contributed to our understanding of the stages involved in sleep. has extremely high temporal resolution.
weakness
- main drawback is the generalised nature of the information received. the EEG signal is not useful for pinpointing the exact source of neural activity and it does not allow researchers to distinguish between activities originating in different but adjacent locations
evaluation
ERP
strength
- limitations of EEG are addressed in ERPs - bring much more specificity to the measurement of neural processes. they have excellent temporal resolution which has led to their widespread use in the measurement of cognitive functions and deficits.
weakness
- critics point to a lack of standardisation in ERP methodology between different studies which makes it difficult to confirm findings. background noise and extraneous material must be completely eliminated and this is not always easy to achieve
post mortem examinations
strengths
- was vital in providing a foundation for early understanding of key processes in the brain. Broca and Wernicke relied on post mortem studies in establishing links between language, brain and behaviour decades before neuroimaging was possible
weaknesses
- causation is an issue, observed damage to the brain may not be linked with the deficits under review but maybe to some other trauma or decay. raise ethical issues of consent from the patient before death. patients may not be able to provide informed consent