1. EEG Experiment for Extra Credit Sign up on the sheet

2. Structural and Functional Imaging Cortical Flattening –Software such as BrainVoyager can “inflate” the cortex like a balloon so that sulci and gyri are “flattened” –functional data can be transformed with the same complex function –functional and structural data can be overlaid so that distribution on cortical sheet can be visualized

3. Principles of MRI

4. Some terms: –Nuclear Magnetic Resonance (NMR) quantum property of protons energy absorbed when precession frequency matches radio frequency –Magnetic Resonance Imaging (MRI) uses spatial differences in resonance frequencies to form an image basis of anatomical MRI –functional Magnetic Resonance Imaging (fMRI) exploits magnetic properties of hemaglobin to create images changes in cortical blood flow

5. Principles of MRI Some terms: –Nuclear Magnetic Resonance (NMR) quantum property of protons energy absorbed when precession frequency matches radio frequency –Magnetic Resonance Imaging (MRI) uses spatial differences in resonance frequencies to form an image basis of anatomical MRI –functional Magnetic Resonance Imaging (fMRI) exploits magnetic properties of hemaglobin to create images changes in cortical blood flow

6. Principles of MRI Some terms: –Nuclear Magnetic Resonance (NMR) quantum property of protons energy absorbed when precession frequency matches radio frequency –Magnetic Resonance Imaging (MRI) uses spatial differences in resonance frequencies to form an image basis of anatomical MRI –functional Magnetic Resonance Imaging (fMRI) exploits magnetic properties of hemaglobin to create images changes in cortical blood flow

7. Principles of MRI Some terms: –Nuclear Magnetic Resonance (NMR) quantum property of protons energy absorbed when precession frequency matches radio frequency –Magnetic Resonance Imaging (MRI) uses spatial differences in resonance frequencies to form an image basis of anatomical MRI –functional Magnetic Resonance Imaging (fMRI) exploits magnetic properties of hemaglobin to create images changes in cortical blood flow

8. Principles of NMR Protons are like little magnets –they orient in magnetic fields like compass needles –what way do they normally point?

9. Principles of NMR Protons are like little magnets –they orient in magnetic fields like compass needles –what way do they normally point? –normally aligned with Earth’s magnetic field

10. Principles of NMR Protons are like little magnets –they orient in magnetic fields like compass needles –what way do they normally point? –normally aligned with Earth’s magnetic field –NMR uses a big magnet to align all the protons in a sample (e.g. brain tissue)

11. Principles of NMR Protons are like little magnets –Radio Frequency pulse will knock protons at an angle relative to the magnetic field

12. Principles of NMR Protons are like little magnets –Radio Frequency pulse will knock protons at an angle relative to the magnetic field –once out of alignment, the protons begin to precess

13. Principles of NMR Protons are like little magnets –Radio Frequency pulse will knock protons at an angle relative to the magnetic field –once out of alignment, the protons begin to precess –protons gradually realign with field (relaxation)

14. Principles of NMR Protons are like little magnets –Radio Frequency pulse will knock protons at an angle relative to the magnetic field –once out of alignment, the protons begin to precess –protons gradually realign with field (relaxation) –protons “echo” back the radio frequency that originally tipped them over –That radio “echo” forms the basis of the MRI image

15. Principles of NMR Protons are like little magnets –The following simple equation explains MRI image formation

16. MRI Image Formation First you need a scanner: –The first MRI scanner

17. MRI Image Formation Modern Scanners

18. MRI Image Formation Our Scanner

19. MRI Image Formation Our Scanner

20. MRI Image Formation Our Scanner

21. MRI Image Formation Our Scanner

22. MRI Image Formation MRI Image formation –resonance frequency depends on field strength –gradient coils alter resonance frequency over distance –slight differences in the “echo” frequency indicate the location of each proton –second-dimension of a slice is coded by the phase of the protons field gradient = frequency gradient

23. Functional Imaging Functional Imaging must provide a spatial depiction of some process that is at least indirectly related to neural activity in most imaging (i.e. PET, fMRI) that process is change in blood oxygenation related to changes in regional cerebral blood flow Why should we measure blood oxygenation?

24. Functional Imaging Why should we measure blood oxygenation? Onset of a stimulus (or cognitive task) changes local blood oxygenation –first with a decrease –then with an “overshoot”

25. Functional Imaging Why should we measure blood oxygenation? Onset of a stimulus (or cognitive task) changes local blood oxygenation –first with a decrease –then with an “overshoot” How do we measure changes in blood oxygenation?