Chapter 6: Self-assessment Questions

1. How does PET imaging record signals? What are the major differences between the physiological properties to which PET is sensitive to and the physiological properties to which BOLD fMRI is sensitive?
2. What did Roy and Sherrington speculate about the physiological correlates of brain function?
3. What is different about the magnetic properties of oxygenated and deoxygenated hemoglobin?
4. What two factors contributed to the development of fMRI?
5. What does the abbreviation “BOLD” represent? What causes BOLD contrast?
6. How did Ogawa and colleagues demonstrate the existence of BOLD contrast? Describe some of their early experiments.
7. What is the difference between exogenous and endogenous contrast? Why might exogenous contrast agents be used?
8. What were some of the characteristics of the early fMRI studies? What did they demonstrate?
9. What was different about the 1992 study by Blamire and colleagues, compared to those from other groups?
10. Why is there an overcompensatory hemodynamic response in the brain following neuronal activity?
11. What is the basic shape of the fMRI BOLD hemodynamic response?
12. How long is the delay between stimulus onset and the peak of the hemodynamic response for short stimulus durations?
13. What causes the post-stimulus undershoot?
14. What is the initial dip? Why has its existence been difficult to demonstrate conclusively?
15. Why might the initial dip have better functional resolution than the traditional positive BOLD response?
16. What are the major divisions of fMRI data, from subjects down to voxels?
17. What are DISDAQs, and why are they sometimes incorporated into imaging protocols?