What is the difference between calcium imaging and electrophysiology?

Calcium imaging is a microscopy technique, which uses fluorescent protein sensors to visualize the activity of hundreds of individual neurons at once in cell culture or in living animals. And it can track the activity of the same neuronal populations over time. Fluctuations in intracellular calcium can be detected by changes in fluorescence, which is an indirect indicator of neural activity.

Electrophysiology is a technique used to measure the activity of ion channels in real time. Ion channels that are present in the cell membranes allow ions to pass through in a selective manner. The flux of charged particles created by the ion channels generates a current, which can be quantified by electrophysiology measurements.