Fluorescent organic dyes are widely used as reporters of dynamic changes in various cellular processes. Because calcium ions control key functions in all types of neurons, imaging dynamic local changes in intracellular calcium concentration has become an important experimental readout in neurobiology [49]. Pioneering studies show that combination of calcium imaging with microfluidic applications, such as controlling neuronal connectivity and local perfusion in vitro [17] or immobilization of a whole organism [50], can provide powerful ways to image dynamics of neuronal processes. Moreover, fluorescent reporter proteins combined with microfluidic devices have been used to study how synaptic transmission is coupled to local changes in dendritic protein synthesis, a prerequisite of many forms of synaptic plasticity [25], and for quantitative analysis of presynaptic receptor localization and axon-dendrite contact formation [51].
