Ca2+ Caging and Uncaging

Neuronal Ca²⁺ signals occur in a very complex way. Direct imaging of Ca²⁺ changes in the soma, dendrites, and even single spines on fast time-scales greatly helps us understand the generation mechanism of diverse Ca²⁺ signaling events. However, Ca²⁺ imaging itself does not give information about the causal relationships between specific Ca²⁺ signals and specific functions. With the rapid improvements of new caged compounds, application or usage of uncaging/caging techniques has been expanded widely in biological research. Using caged compounds, the Ca²⁺ concentration in the target area can be either increased or lowered on a given time scale to various degrees. The most important advantage of the uncaging/caging technique is to control the intensity, duration, and area of light with high precision at a single cell level, providing very accurate control of biomolecules within a limited space at a given time. This chapter discusses how to use caged Ca²⁺ compounds in studying neuronal functions and Ca²⁺ signaling.