Measurements and Modeling of Transient Blood Flow Perturbations Induced by Brief Somatosensory Stimulation

Reswanul Khan1, 2, Andrew K Dunn3, Timothy Q Duong4, David Ress*, 1
1 Psychology, Neurobiology, Center for Perceptual Systems, Imaging Research Center, The University of Texas at Austin, USA
2 Department of Physics, The University of Texas at Austin, USA
3 Department of Biomedical Engineering, The University of Texas at Austin, USA
4 Research Imaging Institute, Departments of Ophthalmology, Radiology and Physiology, University of Texas Health Science Center, San Antonio, TX, USA

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© Khan et al; Licensee Bentham Open

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the UT Austin Imaging Research Center, 3925B West Braker Lane, R9975, Austin, TX 78759 USA; E-mail:


Proper interpretation of BOLD fMRI and other common functional imaging methods requires an understanding of neurovascular coupling. We used laser speckle-contrast optical imaging to measure blood-flow responses in rat somatosensory cortex elicited by brief (2 s) forepaw stimulation. Results show a large increase in local blood flow speed followed by an undershoot and possible late-time oscillations. The blood flow measurements were modeled using the impulse response of a simple linear network, a four-element windkessel. This model yielded excellent fits to the detailed time courses of activated regions. The four-element windkessel model thus provides a simple explanation and interpretation of the transient blood-flow response, both its initial peak and its late-time behavior.

Keywords: brain, hemodynamics, vasodilation, oxygen transport, microvessels, brain mapping.