key stage 4 magnetic resonance imaging watching the brain at work
TRANSCRIPT
Key Stage 4
Magnetic Resonance Imaging
Watching the brain at work
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If you wiggle your fingers……there is more activity in these brain
areas.
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These areas of the brain need more oxygen…
activation statebaseline
More blood flow
More oxygenated blood
Less distortion of magnetic field
More fMRI signal
…which the blood delivers
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An experiment
rest move rest move rest move restTask FMRI signal
time
These areas of the brain are active
during movement, but not rest.
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The FMRI scanner looks at one brain ‘slice’ at a time…
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You can locate an area of the brain using X, Y, and Z co-ordinates.
The image is divided into
voxels. Voxels are 3D pixels.
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The trace shows that this voxel is relevant to the task.
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Colour Vision• FMRI does not give an
absolute measure, so you need to look at signal change.
• To isolate one brain function, compare the condition you are investigating to a control condition.
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The subtraction approach: vision
View grey
stimuli (control)
View colourstimuli
grey colour grey colour grey colour greyTask:fMRI signal
time
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The subtraction approach: vision
- =
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