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Key Stage 4 Magnetic Resonance Imaging Watching the brain at work www.oxfordsparks.net/mri.

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Presentation on theme: "Key Stage 4 Magnetic Resonance Imaging Watching the brain at work www.oxfordsparks.net/mri."— Presentation transcript:

1 Key Stage 4 Magnetic Resonance Imaging Watching the brain at work

2 If you wiggle your fingers… …there is more activity in these brain areas.

3 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

4 An experiment rest move rest move rest move rest Task FMRI signal time These areas of the brain are active during movement, but not rest.

5 The FMRI scanner looks at one brain slice at a time…

6 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.

7 The trace shows that this voxel is relevant to the task.

8 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.

9 The subtraction approach: vision View grey stimuli (control) View colour stimuli grey colour grey colour grey colour grey Task: fMRI signal time

10 The subtraction approach: vision - =


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