BME Seminar Series: Xiaojun Cheng
Content
Speckle-based techniques for mapping mouse and human brain dynamics
Xiaojun Cheng, PhD
Boston University
Thursday, December 3
Morrill III rm. 203
1:00-2:15 PM
Speckles arise from the interference of coherence light scattered by moving scatterers such as red blood cells, making them sensitive to measuring brain dynamics. We have demonstrated the capability of speckle-based techniques to measure dynamics in both mouse and human brains non-invasively by exploiting speckle statistics. For mouse brain measurements, we quantify the fast-decaying blood flow dynamics, and discovered a novel slower-decaying dynamics component related to cellular motility, and obtain the spatial maps of these parameters with laser speckle contrast imaging (LSCI). We have obtained the variations of fast and slow dynamics in mice before and longitudinally post-stroke to monitor stroke evolution. This label-free optical technique establishes the foundation to measure brain dynamics including cerebral blood flow (CBF) and other dynamics such as intracellular motility and opens opportunities to measure neuronal cell movement associated with neural activation. For human brain measurements, we have developed a high density fiber-based speckle contrast optical spectroscopy (SCOS) system to map human CBF and brain functions. We show that SCOS outperforms traditional diffuse correlation spectroscopy (DCS), which is the state-of-the-art optical method to measure human CBF, by more than an order of magnitude in signal to noise ratio (SNR) with lower financial cost. We also demonstrated human brain function measurements during a cognitive task with a source detector grid, illustrating the feasibility of spatial localization of brain activation with SCOS. This technology will establish the foundation for devices that use speckle statistics to non-invasively monitor human CBF, which will impact fundamental neuroscience research as well as clinical applications.
About Xiaojun Cheng: Dr. Xiaojun Cheng is a Research Assistant Professor leading an independent lab in the Neurophotonics Center, Department of Biomedical Engineering at Boston University. Dr. Cheng has a Ph.D. background in Physics conducting fundamental studies of wave scattering inside ordered and disordered media at the City University of New York. She has then worked as a postdoc at Boston University with Dr. David Boas on modeling and system designs for various optical imaging techniques. She has worked on optical microscopy for mouse brain imaging using multi-photon microscopy, optical coherence tomography (OCT) and laser speckle contrast imaging (LSCI). She has also worked on measuring human brain hemodynamics using techniques including functional near infrared spectroscopy (fNIRS), diffuse correlation spectroscopy (DCS), and has developed the novel fiber-based speckle contrast optical spectroscopy (SCOS) system and the data processing pipeline for human cerebral blood flow measurements. Dr. Cheng’s main focus is to exploit the speckle pattern arising from the interference of coherent scattered light to probe brain structure and function in health and disease.