FIGURE 5.
CBV, capillary flow, and pial artery diameter responses to SD. A: time-lapse subtraction images of transilluminated cortical light transmission show a spreading concentric wave of an initial increase in light transmittance (i.e., CBV reduction, I) followed by a decrease in light transmittance (i.e., CBV increase, II) images in a rat (left panel) and a cat (right panel) under urethane/α-chloralose anesthesia. Time after SD induction is indicated on the top left of each image. Arrow: the site of KCl injection. [Modified from Tomita et al. (481).] B: capillary blood flow dynamics during SD studied by line scans using in vivo multi-photon microscopy (top panel) through a closed cranial window in a representative isoflurane-anesthetized rat (postnatal day 15) show blood cell flow arrest (middle panel) during the DC shift (bottom panel) that corresponds to component I. Following repolarization, there was a rebound increase in blood flow (component II). [Modified from Chuquet et al. (59).] C: combined electrophysiological recording and multimodal optical imaging in a representative isoflurane-anesthetized mouse show changes in total hemoglobin ([Hbtot]), pial artery diameter (PAD), hemoglobin O2 saturation (SatO2; %), and optical intrinsic signal (OIS) in relation to the DC shift (field potential; mV). Different vasomotor components (I–IV) are labeled as described in the text as well as in Figure 3. Note the severe vasoconstriction and hemoglobin desaturation during the DC shift (I), and long-lasting and severe post-SD oligemia (IV). [Hbtot], PAD, and OIS are normalized to pre-CSD baseline. [Modified from Chang et al. (54).]