Mapping brain circuit function in vivo using two-photon fluorescence microscopy.

Mapping the activity of neuronal circuits with high resolution in the intact brain is a fundamental step toward understanding brain function. In the last several years, nonlinear microscopy combined with fluorescent activity reporters has become a crucial tool for achieving this goal. In this review article, we will highlight the principles underlying nonlinear microscopy and discuss its application to neuroscience, focusing on recent functional studies in the rodent neocortex in combination with genetically encoded calcium indicators.