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Proceedings Paper

Miniature device for chronic, label-free multi-modal optical imaging of cortical hemodynamics in rats
Author(s): Raanan Gad; Iliya Sigal; Dene Ringuette; Margaret Koletar; Bojana Stefanovic; Ofer Levi
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Paper Abstract

We report on a novel miniature head-mounted imaging system for simultaneous optical recording of brain blood flow and changes in brain blood oxygenation in a rat. Measurements of blood flow speeds are accomplished using Laser Speckle Contrast Imaging (LSCI) technique, while changes in blood oxygenation are measured via Intrinsic Optical Signal Imaging (IOSI) technique. A single multi-wavelength (wavelength = 680, 795, 850 nm) package of vertical cavity surface emitting lasers (VCSELs) is used as the sole brain illumination source. VCSELs enable rapid toggling between wavelengths, and between high-coherence and low-coherence modes, necessary for LSCI and IOSI, respectively. The combination of a miniature light source and a small 10-bit CCD camera sensor lead to a sub-20 g device mass. The miniature imaging system, including the lens, camera, and illumination lasers, is packaged as a module, and is mounted on a chronic implanted observation window that is surgically placed in the skull, allowing for repeated measurements and removal of the imaging system from the rats head after the imaging session. The imaging system allows for a 2mm-diameter field of view and a resolution of 7.4 µm. It will allow neurophysiologists to correlate standard behavioural assays to neurovascular response in animal models, and thus enrich their understanding of neurovascular coupling dynamics of brain disorders and diseases such as stroke and epilepsy.

Paper Details

Date Published: 10 March 2015
PDF: 5 pages
Proc. SPIE 9305, Optical Techniques in Neurosurgery, Neurophotonics, and Optogenetics II, 93052H (10 March 2015); doi: 10.1117/12.2080622
Show Author Affiliations
Raanan Gad, Univ. of Toronto (Canada)
Iliya Sigal, Univ. of Toronto (Canada)
Dene Ringuette, Univ. of Toronto (Canada)
Margaret Koletar, Sunnybrook Research Institute (Canada)
Bojana Stefanovic, Sunnybrook Research Institute (Canada)
Ofer Levi, Univ. of Toronto (Canada)

Published in SPIE Proceedings Vol. 9305:
Optical Techniques in Neurosurgery, Neurophotonics, and Optogenetics II
Henry Hirschberg M.D.; E. Duco Jansen; Samarendra K. Mohanty; Nitish V. Thakor; Qingming Luo; Steen J. Madsen, Editor(s)

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