Figure 4.

Major CBF-response reduction without CMRO₂ impairment. Time courses of CBF, CBV, CMRO₂, and deoxy-Hb during baseline conditions with superfusion of aCSF (no additional vehicle or inhibitor, n=24) and superfusion of inhibitory cocktails (CBF response inhibition, n=12) for a stimulation intensity of 2.0 mA. Shaded areas denote 95% confidence intervals. At baseline, CBF increases by ∼50%, CBV by ∼20% (in conformity with Grubbs relationship), CMRO₂ by ∼10%, and deoxy-Hb level decreases by ∼15%. The inhibitory cocktail reduces CBF responses by two-thirds, leaving CMRO₂ unchanged. No change in deoxy-Hb level can be detected under these conditions (‘BOLD-blind' coupling). Shaded areas denote 95% confidence intervals.