Light-Addressed Stimulation Under $\hbox {Ca}^{\bf 2+}$ Imaging of Cultured Neurons

Light addressing is an emerging and sophisticated technique that can induce pinpoint and/or patterned neuronal activation in cultured neurons. We previously developed a light-addressable electrode using hydrogenated amorphous silicon (a-Si:H), which was sandwiched between a tin oxide (SnO₂) substrate and a passivation layer of zinc antimonate (ZnOSb₂O₅) dispersed epoxy. This research developed an experimental system that simultaneously implemented light-addressed stimulation and Ca²⁺ imaging of neuronal activities. The translucent and thin laminated structure of our electrode permitted optical accesses from two directions: Ca²⁺ imaging from above and light addressing from beneath. The submillisecond bright/dark switching property of our electrode offered light-addressed stimulation without causing interference with Ca²⁺ imaging. To provide patterned illumination for light addressing, a digital micromirror device was installed in the system as an active photomask. The system could induce pinpoint neuronal activation at a cellular level.