The multifunction nerve stimulator S8 was invented in the mid-20th century. It was commonly used to inject current into muscles and cardiac cells to elicit a response. Using frog muscles and hearts, an Italian physician, Luigi Galvani, showed that electricity was inherent in organic tissue. Over the last fifty years or so electro-therapy has shown a very rapid development. This equipment is still functional. I am using the stimulator to send electrical impulses into neurons and record subsequent changes in nerve activity characterized by the movement of charged molecules across the cell membrane.