Fluctuations and stimulus-induced changes in blood flow observed in individual capillaries in layers 2 through 4 of rat neocortex
Fluctuations and stimulus-induced changes in blood flow observed in individual capillaries in layers 2 through 4 of rat neocortex
复制标题
DOI：
10.1073/pnas.95.26.15741
复制
发表时间：
1998-12-22
影响因子：
11.1
通讯作者：
Denk, W
中科院分区：
文献类型：
--
作者：
Kleinfeld, D;Mitra, PP;Denk, W
在单个毛细血管水平的皮质血流以及神经元活动与毛细血管中的血流的耦合是正常和患病脑中的内稳态的基本方面。为了探索血流动力学在这个水平上，我们用双光子激光扫描显微镜成像的红细胞（RBC）在个别毛细血管的运动，位于远600 μ m以下的软脑膜在大鼠的初级躯体感觉皮层，这个深度包括皮质层的最高密度的神经元和毛细血管。我们观察到，流动是相当可变的，并表现出约0.1 Hz的时间波动，以及长期的失速和偶尔的方向反转。平均而言，RBC的速度和通量（每单位时间的细胞数）在低通量值下线性共变，线性密度约为70个细胞/mm，随后在高通量值下速度趋于平稳。因此，红细胞的平均速度和密度在高通量值下比在低值下更大。在多个触须或后肢的刺激下，观察到位于躯体感觉皮层的适当解剖区域的流量的时间锁定变化。虽然我们能够在一些单一试验中检测刺激诱导的红细胞流量和速度的变化，但刺激诱发的流量变化的幅度在很大程度上被基础波动所掩盖。平均而言，红细胞的流量和速度在刺激时瞬时增加，尽管红细胞的线密度略有下降，这些发现与刺激诱导的毛细血管流动阻力降低一致。
Cortical blood flow at the level of individual capillaries and the coupling of neuronal activity to flow in capillaries are fundamental aspects of homeostasis in the normal and the diseased brain. To probe the dynamics of blood flow at this level, we used two-photon laser scanning microscopy to image the motion of red blood cells (RBCs) in individual capillaries that lie as far as 600 mu m below the pia mater of primary somatosensory cortex in rat; this depth encompassed the cortical layers with the highest density of neurons and capillaries. We observed that the flow was quite variable and exhibited temporal fluctuations around 0.1 Hz, as well as prolonged stalls and occasional reversals of direction. On average, the speed and flux (cells per unit time) of RBCs covaried linearly at low values of flux, with a linear density of approximate to 70 cells per mm, followed by a tendency for the speed to plateau at high values of flux. Thus, both the average velocity and density of RBCs are greater at high values of flux than at low values. Time-locked changes in flow, localized to the appropriate anatomical region of somatosensory cortex, were observed in response to stimulation of either multiple vibrissae or the hindlimb, Although we were able to;detect stimulus-induced changes in the flux and speed of RBCs in some single trials, the amplitude of the stimulus evoked changes in flow were largely masked by basal fluctuations. On average, the flux and the speed of RBCs increased transiently on stimulation, although the linear density of RBCs decreased slightly, These findings are consistent with a stimulus-induced decrease in capillary resistance to flow.