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. Author manuscript; available in PMC: 2017 Jun 1.
Published in final edited form as: Trends Cogn Sci. 2016 Apr 30;20(6):425–443. doi: 10.1016/j.tics.2016.03.014

Figure 3. Post-hoc vascular normalization techniques.

Figure 3

(a) Traditionally, hypercapnia has been used to elicit a BOLD signal change with no change in neural activity or consumption of oxygen; this response can be used to normalize the BOLD response measured in task runs. Breathholding (BH, top) can be used to induce hypercapnia. Recently, it was found that the Amplitude of Low Frequency Fluctuations from RS-fMRI (RS-ALFF, bottom) mimics the hypercapnic BOLD response [69], and thus may be used instead of a hypercapnic run. Figure reproduced with permission from [154]. (b) The ALFF of the residuals of task fMRI data (GLMres-ALFF) also looks very similar to RS-ALFF (left) and can be used to rescale the BOLD signal change (vascular autorescaling, or VasA). Figure modified with permission from [73]. (c) Decrease in BOLD response to a sensorimotor task as a function of increasing age in the occipital lobe (blue) is abolished after scaling the sensorimotor-task with RS-ALFF (red), where each point represents an individual. Figure adapted with permission from [74].