Abstract
In vivo 2-photon imaging of neurons that have been bulk-loaded with fluorescent calcium indicator dyes is permitting many fundamental principles of neural circuit organization and development to be uncovered. In this article, we describe the materials and procedures that we have used in our investigations of ferrets, tree shrews, and mice. Special attention is given to the design and construction of custom stereotaxic devices and the prevention of stray light from entering the 2-photon microscope during vision experiments.