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Brain Scanning Techniques
MRI Scan (Magnetic Resonance Imaging) PET Scan (Positron Emission Tomography)
Structural technique, providing an image of a slice Functional technique which records activity of the
through the brain. brain whilst it occurs.
Uses a powerful magnetic field to influence Patients are injected with a tracer which is
hydrogen atoms in water. radioactive versions of chemicals (like water and
Positively charged hydrogen atoms point towards glucose). It reaches the brain after one minute and
the magnetic field when the scanner turns on. decays after 215.
Radio waves pass through the head by the As it decays it releases positions (small amounts of
scanner, and the positively charged atoms return radioactivity). This is detected by the scanner and is
to the correct place, which admit radio waves that used to help detect activity in brain tissue.
the scanner detects. By measuring radiation level, you can see what
Different areas of the brain admit different parts of the brain are active and not. A colour image
amounts of radio waves, which appear as is produced. Warmer colours show more activity,
different densities (grey areas). If a lot of cooler colours show less activity.
hydrogen atoms the area will appear white. Radioactivity is in the form of gamma rays which
They allow psychologists to compare structure of occurs when positrons collide.
brains that are functioning properly and Participants are usually scanned several times in
abnormally. Also to see if brain abnormality has two conditions. One inactive, and the other when
caused a symptom. doing an activity.
We can examine male and female brains, as well It shows parts of the brain required to carry out
as young and old brain to look at the variations tasks.
between them. It can help to explain cognitive
Left Brain Functions Right Brain Functions
Number Skills Music Awareness
Reasoning Art Awareness
Scientific Skills 3d Forms
Written Language Insight
Spoken Language Imagination
Right Hand Control Left Hand Control
Gender Differences in Brain Laterisation
Male Brains Female Brains
Greater Laterisation of brain more definite and Language functions less lateralized, jobs are spread
localised. out more equally in both hemispheres.
Left temporal lobe 38% longer than the right. No difference in left and right temporal lobes.
Rhyming tasks mens brains localised to the left. Rhyming tasks lateralisation was symmetrical.
- Language; for most right handed people the language
function is lateralised on the left hemisphere, but the
reverse isn't true of left handed people. In left-handed
people language is lateralised to the right in less than
20% and 20% are bilateral. The rest have their language
function in the left hemisphere!