Low-frequency calcium oscillations accompany deoxyhemoglobin oscillations in rat somatosensory cortex
Low-frequency calcium oscillations accompany deoxyhemoglobin oscillations in rat somatosensory cortex
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DOI：
10.1073/pnas.1410800111
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发表时间：
2014-10-28
影响因子：
11.1
通讯作者：
Pan, Yingtian
中科院分区：
文献类型：
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作者：
Du, Congwu;Volkow, Nora D.;Pan, Yingtian
血氧水平依赖(BOLD)信号的自发低频振荡(LFO)被用于脑功能磁共振成像，但其来源尚不清楚。在这里，我们使用光学成像来评估来自血管信号的LFO是否与振荡的细胞内钙(Ca-i(2+))和大鼠躯体感觉皮质的局部场电位共同变化。我们观察到组织中Ca-i(2+)振荡的频率(类似于0.07赫兹)与大血管和毛细血管中脱氧血红蛋白(HBr)和氧合血红蛋白(HBO2)的LFO相似。组织内Hbr和HbO2的波动与Ca-i(2+)振荡相关，滞后时间接近S 5-6，组织内的Ca-i(2+)和血红蛋白振荡对高碳酸血症不敏感。而动脉和静脉的脑血流速度(CBFv)波动频率较高(接近0.12赫兹)，对高碳酸血症反应敏感。而在实质组织中，CBFv在0.06赫兹和0.12赫兹附近均有峰值振荡。虽然高碳酸血症使高频CBFv振荡(类似于0.12 Hz)减少，但其低频成分(类似于0.06 Hz)不受影响。较高的CBFV振荡对高碳酸血症的敏感性，从而触发血管扩张，这表明它对血管效应的依赖不同于在HBr、HBO(2)、Ca-i(2+)和低频率组织CBFv中检测到的对高碳酸血症不敏感的LFO。血流动力学LFO与Ca-i(2+)和神经元放电(局部场电位)相关，表明它们直接反映神经元的活动(可能也反映神经胶质细胞)。这些发现表明，Hbr的波动(BOLD振荡的基础)与细胞的振荡活动有关，并且可以在整个血管树(动脉、毛细血管和静脉)中检测到。
Spontaneous low-frequency oscillations (LFOs) of blood-oxygenlevel- dependent (BOLD) signals are used to map brain functional connectivity with functional MRI, but their source is not well understood. Here we used optical imaging to assess whether LFOs from vascular signals covary with oscillatory intracellular calcium (Ca-i(2+)) and with local field potentials in the rat's somatosensory cortex. We observed that the frequency of Ca-i(2+) oscillations in tissue (similar to 0.07 Hz) was similar to the LFOs of deoxyhemoglobin (HbR) and oxyhemoglobin (HbO2) in both large blood vessels and capillaries. The HbR and HbO2 fluctuations within tissue correlated with Ca-i(2+) oscillations with a lag time of similar to 5-6 s. The Ca-i(2+) and hemoglobin oscillations were insensitive to hypercapnia. In contrast, cerebral-blood-flow velocity (CBFv) in arteries and veins fluctuated at a higher frequency (similar to 0.12 Hz) and was sensitive to hypercapnia. However, in parenchymal tissue, CBFv oscillated with peaks at both similar to 0.06 Hz and similar to 0.12 Hz. Although the higher-frequency CBFv oscillation (similar to 0.12 Hz) was decreased by hypercapnia, its lower-frequency component (similar to 0.06 Hz) was not. The sensitivity of the higher CBFV oscillations to hypercapnia, which triggers blood vessel vasodilation, suggests its dependence on vascular effects that are distinct from the LFOs detected in HbR, HbO(2), Ca-i(2+), and the lower-frequency tissue CBFv, which were insensitive to hypercapnia. Hemodynamic LFOs correlated both with Ca-i(2+) and neuronal firing (local field potentials), indicating that they directly reflect neuronal activity (perhaps also glial). These findings show that HbR fluctuations (basis of BOLD oscillations) are linked to oscillatory cellular activity and detectable throughout the vascular tree (arteries, capillaries, and veins).