Dr. G. is providing an electric stimulus to the nerve in the arm of Cole, one of my pre-med students studying biomedical engineering. The stimulus causes the nerves in his arm to fire and Dr. G. uses an instrument to measure the voltage of that response and display it on the screen. From that information, he can calculate the speed and strength at which signals propagate down Cole's arm and determine if he has any neurological disease, which he didn't.
The screen shows Cole's nerve firing on the top, and my own brainwave activity on the bottom.
Then, to my surprise, Dr. G. let the students measure each other's nerves in the same way! It was pretty cool and they enjoyed it. Elysa, another pre-med student, was particularly interested and asked lots of great questions.
The thingy taped to his wrist is the sensor, and the red and black probes being applied to his palm are the electrical stimulus. It zaps him with a medium-voltage (50-150 volts) which causes the chain reaction in his nerves. The chain reaction continues down the nerve and is detected by the sensor. It's cool that we spent a few weeks talking about the electro-physiology of all this, and then we got to zap each other and see it happen in "real life".