功能性神經造影利用腦部血流量的變化來繪制的大腦活動譜圖,，然而神經突觸前和突觸后活動的作用目前還是未知的領域,，它可能是潛在的細胞途徑,。
在6月26日的《神經元》（Neuron）雜志上,，Petzold等人利用作用于活體的多光子顯微鏡,，測量了小鼠的神經突觸前的活動,，突觸后神經元和星形膠質細胞鈣的反應,，以及在氣味刺激下紅細胞的速度和嗅覺纖維球的流量等數據,。
結果表明，氣味誘發(fā)的纖維球毛細血管中的功能性充血與谷氨酸的釋放高度相關,，卻不需要神經突觸后活動,。氣味的刺激會誘導星形膠質細胞后段的鈣瞬變和相關上行動脈的擴張。而星形膠質細胞中功能性充血的鈣含量升高依賴于星形膠質細胞代謝型谷氨酸受體5和環(huán)氧合酶的激活,。星形膠質細胞谷氨酸轉運體也通過獨立于鈣上升和環(huán)氧合酶激活的機制來幫助功能性充血,。
這些由谷氨酸啟動的途徑對神經突觸活動和功能性充血纖維球的聯(lián)結起到至關重要的作用。（生物谷Bioon.com）
生物谷推薦原始出處：
Neuron,，Vol 58, 897-910, 26 June 2008,，Gabor C. Petzold, Venkatesh N. Murthy
Coupling of Neural Activity to Blood Flow in Olfactory Glomeruli Is Mediated by Astrocytic Pathways
Gabor C. Petzold,1,2 Dinu F. Albeanu,1,2 Tomokazu F. Sato,1,2 and Venkatesh N. Murthy1,2,
1 Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
2 Center for Brain Science, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
Corresponding author
Venkatesh N. Murthy
[email protected]
Summary
Functional neuroimaging uses activity-dependent changes in cerebral blood flow to map brain activity, but the contributions of presynaptic and postsynaptic activity are incompletely understood, as are the underlying cellular pathways. Using intravital multiphoton microscopy, we measured presynaptic activity, postsynaptic neuronal and astrocytic calcium responses, and erythrocyte velocity and flux in olfactory glomeruli during odor stimulation in mice. Odor-evoked functional hyperemia in glomerular capillaries was highly correlated with glutamate release, but did not require local postsynaptic activity. Odor stimulation induced calcium transients in astrocyte endfeet and an associated dilation of upstream arterioles. Calcium elevations in astrocytes and functional hyperemia depended on astrocytic metabotropic glutamate receptor 5 and cyclooxygenase activation. Astrocytic glutamate transporters also contributed to functional hyperemia through mechanisms independent of calcium rises and cyclooxygenase activation. These local pathways initiated by glutamate account for a large part of the coupling between synaptic activity and functional hyperemia in the olfactory bulb.
