Quantitative phase imaging (QPI) in neuroscience

Quantitative phase imaging (QPI) is an emerging label-free modality that attracts significant interest in biomedicine in general and neuroscience in particular. Based on the principle of interferometry, QPI precisely maps the optical pathlength induced by the sample, and, thus, can visualize extremely transparent samples. The QPI field has grown rapidly in the past decade, and reliable instruments have been developed for in-depth biological studies. One particular figure of merit associated with QPI techniques describes the temporal phase sensitivity of instruments. Recently, several common path interferometry methods have been developed, which yield high stability and nanometer scale pathlength sensitivity. In neuroscience, QPI has shown unique capabilities in quantifying neural growth and dynamics in cell cultures, as well as high contrast imaging of brain tissue slices. In this paper, we review the principles of QPI, novel QPI technology, advances in data processing, and a number of exciting applications in neuroscience.