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