PROJECT SUMMARY/ABSTRACT The contraction of muscle cells in organs such as the heart, uterus, urinary bladder and intestine is regulated by and is affecting a complex activity associated with electrical excitation. Our long-term goal is to develop a paradigm-shifting approach for studying the dynamic actions and coupling between electrical and mechanical properties in muscular tissues and organs to better link them to health and diseases such as Parkinson’s disease and heart failure. New short-wave infrared (SWIR; ~1-2.5 µm) light imaging has bands with relatively low blood absorbance and scattering and has been proposed recently for both deep tissue and in vivo imaging. The general objective of this project is to develop an in vivo extracorporeal and endoscopic label-free SWIR approach for mapping patterns of muscular function. Accordingly, label-free multi-spectral datasets recorded simultaneously at optimized SWIR wavelengths will provide novel spectroscopic fingerprints of electro- mechanical actions in muscle tissue. We will use beating hearts of living mice as a platform for developing the technology for high-speed probing at multiple SWIR wavelengths to test the general hypothesis that in vivo intrinsic optical imaging can characterize simultaneously the distinct dynamic spatiotemporal patterns of electrical and mechanical muscular actions. Our Specific Aims are: Aim 1: To demonstrate that intrinsic multi-spectral SWIR light imaging can be used for extracorporeal mapping of cardiac muscle electro-mechanical dynamics. We will use a specialized high-speed SWIR camera and multi-spectral alternating light sources located outside of the body of label-free mice to test the hypothesis that extracorporeal mapping of spatiotemporal patterns of cardiac activity in vivo is feasible in two optical settings: (1a) wide view objective lens assembly for distanced positioning from the body surface to maximize viewing area and intensity of light illumination and probing. (1b) borescope system in contact with the body surface for imaging with minimal media heterogeneity and light loss. Aim 2: To demonstrate functionality of dual-mode endoscopic SWIR system for label-free mapping electrical excitability and mechanical contractility of cardiac muscle. We will test here the hypothesis that low absorbance and scattering of specific wavelengths in blood permits endoscopic probing of the myocardial electrical and mechanical activation, required for mapping deep muscular tissues in cases of large animals or patients. Accomplishing our aims will open the possibility of a new photonic approach for label- free mapping of dynamic excitation and contractile actions in muscular tissues for in vivo research and clinical applications.