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FIG 2. Time courses of the signal intensity changes of the subtraction FAIR images as well as the calculated relative rCBF changes in the same subject as in figure 1 during repeated challenges of breath-holding for 40 seconds after inspiration (A and B) and for 30 seconds after expiration (C and D). Notably, breath-holding after expiration yielded an immediate rCBF increase (arrow, D), whereas rCBF declined initially during breath-holding after inspiration (arrow, B). Owing to transient periods of hyperventilation, blood flow–related signal changes typically went below baseline after breathing resumed
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