Chapter 7 Study Questions

  1. What are the differences between the magnetic properties of oxygenated and deoxygenated hemoglobin?
  2. What time constant is affected by the oxygenation level of blood, as demonstrated by Thulborn and colleagues?
  3. What do the terms “diamagnetic,” “paramagnetic,” and “ferromagnetic” mean?
  4. How does positron emission tomography (PET) imaging work? What are the advantages and disadvantages of PET as compared to MRI/fMRI?
  5. What does the acronym “BOLD” represent?
  6. What causes BOLD contrast? Describe the mechanism for BOLD in as much detail as possible.
  7. How did Ogawa and colleagues demonstrate the existence of BOLD contrast? Describe some of their early experiments.
  8. Why must there be an uncoupling of oxygen supply and oxygen consumption for BOLD contrast to be useful for functional neuroimaging?
  9. Why do Malonek and Grinvald refer to the BOLD response as “watering the entire garden for the sake of one thirsty flower”?
  10. Why might exogenous contrast agents be used for fMRI?
  11. What were some of the characteristics of the early fMRI studies? What did they demonstrate?
  12. What is the basic shape and timing of the fMRI BOLD hemodynamic response?
  13. To what aspects of neuronal activity is the fMRI BOLD response best correlated?
  14. What features of brain physiology might generate negative BOLD signals?
  15. What are partial volume effects?
  16. What are large vessel effects, and why do they matter for fMRI?
  17. What factors, aside from voxel size, influence spatial resolution in fMRI?
  18. What are the disadvantages of high temporal resolution in fMRI?
  19. What is fMRI-adaptation? For what sorts of research questions might it be most useful?
  20. Name and define the two properties of a linear system.
  21. Based on data from early studies, why did researchers describe the fMRI hemodynamic response as being “roughly linear”? In what ways does the hemodynamic response deviate from linearity?
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