Devor Anna, Tian Peifang, Nishimura Nozomi, Teng Ivan C, Hillman Elizabeth M C, Narayanan S N, Ulbert Istvan, Boas David A, Kleinfeld David, Dale Anders M
Department of Neurosciences, University of California, San Diego, California 92093, USA.
J Neurosci. 2007 Apr 18;27(16):4452-9. doi: 10.1523/JNEUROSCI.0134-07.2007.
Synaptic transmission initiates a cascade of signal transduction events that couple neuronal activity to local changes in blood flow and oxygenation. Although a number of vasoactive molecules and specific cell types have been implicated, the transformation of stimulus-induced activation of neuronal circuits to hemodynamic changes is still unclear. We use somatosensory stimulation and a suite of in vivo imaging tools to study neurovascular coupling in rat primary somatosensory cortex. Our stimulus evoked a central region of net neuronal depolarization surrounded by net hyperpolarization. Hemodynamic measurements revealed that predominant depolarization corresponded to an increase in oxygenation, whereas predominant hyperpolarization corresponded to a decrease in oxygenation. On the microscopic level of single surface arterioles, the response was composed of a combination of dilatory and constrictive phases. Critically, the relative strength of vasoconstriction covaried with the relative strength of oxygenation decrease and neuronal hyperpolarization. These results suggest that a neuronal inhibition and concurrent arteriolar vasoconstriction correspond to a decrease in blood oxygenation, which would be consistent with a negative blood oxygenation level-dependent functional magnetic resonance imaging signal.
突触传递引发了一系列信号转导事件，这些事件将神经元活动与局部血流和氧合变化联系起来。尽管已经涉及到许多血管活性分子和特定细胞类型，但刺激诱导的神经元回路激活向血流动力学变化的转变仍不清楚。我们使用体感刺激和一套体内成像工具来研究大鼠初级体感皮层中的神经血管耦合。我们的刺激诱发了一个被净超极化包围的净神经元去极化的中心区域。血流动力学测量表明，主要的去极化对应于氧合增加，而主要的超极化对应于氧合减少。在单个表面小动脉的微观层面上，反应由扩张期和收缩期的组合组成。至关重要的是，血管收缩的相对强度与氧合减少和神经元超极化的相对强度共同变化。这些结果表明，神经元抑制和同时发生的小动脉血管收缩对应于血液氧合的降低，这与负性血液氧合水平依赖性功能磁共振成像信号一致。
