PROJECT SUMMARY Non-invasive imaging of human brain function plays an important role in advancing neuroscience research and understanding neurological diseases. This need has been met primarily by functional magnetic resonance imaging (fMRI). fMRI, though powerful, is an expensive technique that is not suitable for subjects who cannot tolerate small spaces or cannot stay still (e.g. children, psychiatric disorders), and cannot be used for tasks that require subjects to interact with a natural environment, or for tasks that conflict with the scanner noise, e.g. auditory studies. In this context, functional near-infrared spectroscopy (fNIRS) has emerged as an alternative neuroimaging modality with the same physiological basis as fMRI (dynamic changes in hemoglobin concentration as a result of neural activation). A more recently developed technique, diffuse correlation spectroscopy (DCS), shares many of the advantages of fNIRS, while also providing a fundamentally different functional imaging approach through its ability to directly measure blood flow. DCS is substantially more sensitive than NIRS to cerebral blood flow due to the 6x brain vs. scalp perfusion ratio. we propose to develop a multi-channel, compact, inexpensive and scalable functional DCS (fDCS) system with dramatically improved performance vs. fNIRS systems. To this end we will leverage recent advances in long-wavelength (1064 nm) DCS (proposed by our group and demonstrated to bring a 10x SNR improvement vs. DCS at typical NIR wavelengths) in combination with a camera based, interferometric multi-speckle detection approach that offers another 1-2 order of magnitude increase in signal to noise performance without the need for photon counting detectors. We term this approach long-wavelength multi-speckle functional interferometric DCS (LW-mifDCS).

PROJECT NARRATIVE Non-invasive imaging of human brain function plays an important role in advancing neuroscience research and understanding neurological diseases. We propose to develop a novel high-performance non-invasive functional imaging approach based on blood flow measurement using diffuse correlation spectroscopy. To this end we will leverage recent advances in long-wavelength (1064 nm) DCS (proposed by our group and demonstrated to bring a 10x SNR improvement vs. standard DCS) in combination with a camera based, interferometric multi-speckle detection approach that has been shown to offer a further nearly 2 order of magnitude improvement in noise performance without the need for photon counting detectors.