Photoacoustic microscopy of microvascular responses to cortical electrical stimulation
Advances in the functional imaging of cortical hemodynamics have greatly facilitated the understanding of neurovascular coupling. In this study, label-free optical-resolution photoacoustic microscopy (OR-PAM) was used to monitor microvascular responses to direct electrical stimulations of the mouse somatosensory cortex through a cranial opening. The responses appeared in two forms: vasoconstriction and vasodilatation. The transition between these two forms of response was observed in single vessels by varying the stimulation intensity. Marked correlation was found between the current-dependent responses of two daughter vessels bifurcating from the same parent vessel. Statistical analysis of twenty-seven vessels from three different animals further characterized the spatial-temporal features and the current dependence of the microvascular response. Our results demonstrate that OR-PAM is a valuable tool to study neurovascular coupling at the microscopic level.
Additional Information© 2011 SPIE. Paper 10570RR received Oct. 21, 2010; revised manuscript received Apr. 4, 2011; accepted for publication May 5, 2011; published online Jul. 1, 2011. The authors thank Christopher Favazza and Arie Krumholz for helpful discussions, Dr. Alexey Glukhov for technical support, and Professor James Ballard, Dr. Lynnea Brumbaugh, and Ms. Kristy Wendt for help in editing the manuscript. This work was supported by National Institutes of Health Grants Nos. R01 EB000712, EB000712A2S1, R01 EB00071207S2, R01 EB008085, R01 CA113453901, U54 CA136398, and 5P60 DK02057933. L.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.
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