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Methods Used to Investigate Cortical Specialisation
This is where an area of the brain, and its links with other areas of the brain, is deliberately
destroyed or operated on in some way to see how behaviour is affected. In humans, it is
commonly used to operate on and remove brain tumours. In the early 20th century, lobotomy
was often used to treat psychological disorders such as personality disorders and extreme
aggressive behaviour. The most common form of lobotomy was on the frontal lobes. Given their
role in higher mental functioning, this caused people to become passive and unresponsive with
low intelligence and lack of emotion. Today, this form of surgery is rare and only used as a last
resort in severe cases of OCD.
Neurosurgery is used more in non human animal experimentation, especially on rats and mice.
Here, an area of the brain is deliberately destroyed or removed, and psychological functions
such as ability to learn and aggressive behaviour are investigated.
Allows for greater precision in locating damage in the brain
Allows you to compare human or non human behaviour before and after surgery
Lesions can cause brain damage or reduced functioning to other adjacent areas
Difficult to establish cause and effect for a psychological disorder because we cant
determine whether it was caused by the brain defect or whether the disorder caused the
Removing one part of a person's brain might only show how the rest of the brain functions,
wont clearly shown the part or the function, which was taken away but might just show that its
part of an interconnection
Ethical issues of irreversible damage in non humans
Cant generalise findings from animal research to explain human behaviour
Post mortem examinations
This is a method in which the brain of a patient, usually with some known disorder or brain
damage from naturally occurring events e.g. car accident, strokes or tumours to. It allows for
identification of abnormality in areas of the brain, and any damage can be related to
symptoms/ behaviours shown by the person when they were alive.
Broca used post mortem examinations of the brain to compare symptoms a person showed when
alive to damaged areas of the brain found immediately after the person had died. Broca would
write a case history of a person when they were alive and then dissect the brain on death. This
is how he discovered that the function of speech was located in a particular area of the brain
that is now called Broca's area.
Alternatively, a psychologist could potentially take someone who had a psychological disorder,
such as OCD when they were alive and then once they have died open up their brain and see for
example, if the frontal cortex is normal.
Neatly correlate an abnormality in the brain with a known disorder in a patient
Reliable as it is possible to repeat the post mortem examination in the same way to
establish a more accurate correlation
Difficulties in locating a human brain, especially if the disorder is particularly rare
Ethical considerations need consent from next of kin to conduct the examination, who also
has the right to limit the scope of examination i.e. excluding certain organs.
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Electroencephalograms (EEG): Electroencephalography (EEG) is a tool
for measuring electrical activity generated in the brain, which allows the exploration of
neural activity and brain functioning. They record brainwave patterns that come from the
action of millions of neurons, not individual neuron activity.…read more
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Electrical Stimulation: This measures cortical specialisation either by
stimulation of single neurons or groups of neurons on both normal and damaged brains.
One technique is recording activity at the level of the neuron. Here, microelectrodes are
inserted into a single neuron and then the neuron is artificially stimulated with electricity. The
effect on behaviour or a patient's reported sensations are then recorded. This tends to be
done on animals rather than humans as it is an invasive technique.…read more
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Scans don't measure precise neur onal activity only generalised activity in a certain area of
As the brain is always active, cant say that any area of the brain is specifically responsible
during a certain task
Can be very time consuming radioactive substance can take up to an hour to reach the
appropriate area and scanning process can also take up to an hour.…read more