Two-photon mapping of neural circuits

For the study of neural circuits, it would be ideal to be able to discern in a living preparation the interconnections among neurons. Working toward that aim, we have developed a method, using two-photon uncaging of glutamate in brain slices, by which we can detect neurons that are presynaptic to any particular cell. The method, described here, has single-cell resolution and can be applied systematically and quickly to test entire populations of neurons, making it possible to perform online functional analysis of connectivity.