Enager Pia, Piilgaard Henning, Offenhauser Nikolas, Kocharyan Ara, Fernandes Priscilla, Hamel Edith, Lauritzen Martin
Department of Neuroscience and Pharmacology, The Panum Institute, University of Copenhagen, Blegdamsvej, Copenhagen N, Denmark.
J Cereb Blood Flow Metab. 2009 May;29(5):976-86. doi: 10.1038/jcbfm.2009.23. Epub 2009 Apr 1.
Functional neuroimaging signals are generated, in part, by increases in cerebral blood flow (CBF) evoked by mediators, such as nitric oxide and arachidonic acid derivatives that are released in response to increased neurotransmission. However, it is unknown whether the vascular and metabolic responses within a given brain area differ when local neuronal activity is evoked by an activity in the distinct neuronal networks. In this study we assessed, for the first time, the differences in neuronal responses and changes in CBF and oxygen consumption that are evoked after the activation of two different inputs to a single cortical area. We show that, for a given level of glutamatergic synaptic activity, corticocortical and thalamocortical inputs evoked activity in pyramidal cells and different classes of interneurons, and produced different changes in oxygen consumption and CBF. Furthermore, increases in stimulation intensities either turned off or activated additional classes of inhibitory interneurons immunoreactive for different vasoactive molecules, which may contribute to increases in CBF. Our data imply that for a given cortical area, the amplitude of vascular signals will depend critically on the type of input, and that a positive blood oxygen level-dependent (BOLD) signal may be a consequence of the activation of both pyramidal cells and inhibitory interneurons.
功能性神经成像信号部分是由介质引起的脑血流量（CBF）增加所产生的，这些介质如一氧化氮和花生四烯酸衍生物，它们是在神经传递增加时释放的。然而，当不同神经元网络中的活动引发局部神经元活动时，给定脑区内的血管和代谢反应是否存在差异尚不清楚。在本研究中，我们首次评估了激活单个皮质区域的两种不同输入后所引发的神经元反应差异以及CBF和氧消耗的变化。我们发现，对于给定水平的谷氨酸能突触活动，皮质-皮质和丘脑-皮质输入在锥体细胞和不同类型的中间神经元中引发活动，并在氧消耗和CBF方面产生不同的变化。此外，刺激强度的增加要么关闭要么激活了对不同血管活性分子具有免疫反应性的其他类型抑制性中间神经元，这可能有助于CBF的增加。我们的数据表明，对于给定的皮质区域，血管信号的幅度将严重取决于输入的类型，并且正性血氧水平依赖（BOLD）信号可能是锥体细胞和抑制性中间神经元激活的结果。
