We have to measure the protocol of electric shocking mice. The mice are head-fixed, we have to guarantee that the electric current is significant to make the mice learn, but not too big to make the mice violently struggle and break their skull bone. In order to measure the proper electric current value, the simple way to increase the current step by step until the mice break their skull bone. But we think this way is not acceptable by the experimental ethics.
What's a better way? Thanks!