Describe and evaluate scanning techniques as a way of investigating the brain 16 marks. AQA New spec. Everything you need for the exam is in this essay. Full marks
Describe and evaluate scanning techniques as a way of investigating the
brain. (16 marks).
Functional magnetic resonance imaging (FMRI) is a technique which measure brain activity
while a person performs a certain task. It works by detecting changes in the blood
oxygenation and flows that occur because of brain activity in specific parts of the brain.
When a brain is more active it consumes more oxygen and to meet this demands blood flow
is directed to that active area. FMRI produce 3D images known as activation maps showing
which part of the brain are involved in particular mental processes.
Electroencephalogram (EEG) is a technique which measures electrical activity within the
brain via electrodes that are fixed to an individual scalp using a skull cap. The scan recording
represents the brainwave patterns that are generated from the action of millions of neurons
providing an overall account of brain activity. Typical activity patterns include alpha, beta,
delta and theta waves.
Event-Related Potentials (ERP) is technique which uses an EEG to measure small voltage
changes to specific events or stimuli.
Post-mortem examinations are a technique that allows for the analysis of a person brain
after they have died. An individual who may have displayed a particular behaviour while
they were alive may be studied for possible brain damage. Areas of damage within the brain
are examined after death as a means of establishing the likely cause of the illness the person
suffered and this may involve the comparison to a normal brain to assess how different they
are.
A strength of FMRI is unlike any other scanning techniques such as PET it does not use
radiation. If done correctly its risk free, non-invasive and straight forward. This suggests
FMRI are easy and convenient to do. Moreover, they produce images of high spatial
resolution showing the smallest detail and providing a clear picture. However, a limitation to
them is they are expensive to do and are limited to measure blood flow in the brain not the
activity of individual neurons and they have a poor temporal resolution as there is a 5
second time delay, so it takes longer for the scanner to detect changes in the brain.
A strength of EEGS is that they are a vital diagnostic tool to clinicians as give us vital
information on providing diagnosis of condition such as epilepsy. This is as arrhythmic
patterns of activity and random bursts of activity can be easily detected on screen.
Moreover, unlike FMRI it has high temporal resolution, detecting activity of a single
millisecond. Thus, EEGS have practical application as they are useful for real life medical
issues. However, a limitation of EEGS is that it is too basic it does not pinpoint the exact
source of neural activity.
A strength of ERPS is that it has excellent temporal resolution. This allows for the researcher
to be detect changes in the brain quickly. However, a limitation of ERPS is that they are
hard to generalise as they have a lack of standardisation in ERP methodology between
different studies that makes it difficult to confirm and generalise. Moreover, it’s difficult to
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