期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 107, 期 34, 页码 15246-15251出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1006735107
关键词
blood flow; cortical layer; hemodynamic; imaging; somatosensory
资金
- National Institute of Neurological Disorders and Stroke [NS051188, NS-057198, NS057476]
- National Institute of Biomedical Imaging and Bioengineering [EB00790, EB009118, EB2066]
Changes in neuronal activity are accompanied by the release of vasoactive mediators that cause microscopic dilation and constriction of the cerebral microvasculature and are manifested in macroscopic blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signals. We used two-photon microscopy to measure the diameters of single arterioles and capillaries at different depths within the rat primary somatosensory cortex. These measurements were compared with cortical depth-resolved fMRI signal changes. Our microscopic results demonstrate a spatial gradient of dilation onset and peak times consistent with upstream propagation of vasodilation toward the cortical surface along the diving arterioles and downstream propagation into local capillary beds. The observed BOLD response exhibited the fastest onset in deep layers, and the initial dip was most pronounced in layer I. The present results indicate that both the onset of the BOLD response and the initial dip depend on cortical depth and can be explained, at least in part, by the spatial gradient of delays in microvascular dilation, the fastest response being in the deep layers and the most delayed response in the capillary bed of layer I.
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