Patrick M. Boyle et al. JACEP 2018;4:155-167 Multiscale Framework for Simulating Optogenetics in the Heart Optogenetics simulation components are integrated at each level of the multiscale modeling hierarchy: light-sensitive current models at the subcellular scale, cellular expression representation at the cell scale, spatial distribution of light-sensitive cells at the tissue scale, and representation of light attenuation due to photon scattering and absorption at the organ scale. Modified with permission from Boyle et al. (42). AP = action potential; ChR2 = channelrhodopsin-2. Patrick M. Boyle et al. JACEP 2018;4:155-167 2018 American College of Cardiology Foundation