Spatiotemporal evolution of functional hemodynamic changes and their relationship to neuronal activity.
Spatiotemporal evolution of functional hemodynamic changes and their relationship to neuronal activity.
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功能性血流动力学变化的时空演变及其与神经元活动的关系。
DOI：
10.1038/sj.jcbfm.9600091
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Toga,ArthurW
中科院分区：
文献类型：
--
作者：
Sheth,SameerA;Nemoto,Masahito;Guiou,MichaelW;Walker,MelissaA;Toga,ArthurW
脑成像技术，如功能性磁共振成像（fMRI）提供了丰富的信息，大脑组织，但他们的能力，调查精细规模的功能架构是有限的空间特异性的血流动力学反应的基础上。我们研究了大鼠躯体感觉皮层对电后爪刺激的血流动力学反应的时空演变。我们结合了光学固有信号成像和光谱学的优势，以产生组织氧合和血容量功能变化的高分辨率二维图。用激光多普勒血流仪测量脑血流变化，同时记录场电位，以比较血流动力学变化和潜在的神经元活动。对于激活的前2至3秒，血流动力学反应在中央实质病灶中重叠。在接下来的几秒钟内，脑血容量的变化逆行进入供血动脉，氧合变化顺行进入引流静脉。到5至6秒时，反应主要集中在远离中心病灶的血管结构中。血流动力学反应的峰值空间范围随突触活动线性增加。这种空间扩散可能是由于侧向阈下激活或被动血管溢出。这些结果意味着早期微血管的体积和氧合变化定位于激活的神经柱，并且在神经元激活后的2- 3秒窗口内空间特异性将是最佳的。
Brain imaging techniques such as functional magnetic resonance imaging (fMRI) have provided a wealth of information about brain organization, but their ability to investigate fine-scale functional architecture is limited by the spatial specificity of the hemodynamic responses upon which they are based. We investigated the spatiotemporal evolution of hemodynamic responses in rat somatosensory cortex to electrical hindpaw stimulation. We combined the advantages of optical intrinsic signal imaging and spectroscopy to produce high-resolution two-dimensional maps of functional changes in tissue oxygenation and blood volume. Cerebral blood flow changes were measured with laser-Doppler flowmetry, and simultaneously recorded field potentials allowed comparison between hemodynamic changes and underlying neuronal activity. For the first 2 to 3 secs of activation, hemodynamic responses overlapped in a central parenchymal focus. Over the next several seconds, cerebral blood volume changes propagated retrograde into feeding arterioles, and oxygenation changes anterograde into draining veins. By 5 to 6 secs, responses localized primarily in vascular structures distant from the central focus. The peak spatial extent of the hemodynamic response increased linearly with synaptic activity. This spatial spread might be because of lateral subthreshold activation or passive vascular overspill. These results imply early microvascular changes in volume and oxygenation localize to activated neural columns, and that spatial specificity will be optimal within a 2- to 3-sec window after neuronal activation.