Today I had a nerve conduction test
at the doctor's office.
It involved taping electrodes onto my arm and then zapping my arm with a taser-like device. The electrodes were connected to a computer, which measured the time it took for the electrical signal introduced by the taser to travel along my nerve between electrodes. Any nerves that conduct slower than 50 m/s are probably damaged in some way. Mine conducted at at around 65 m/s, except for the ulnar nerve, which runs through the cubital tunnel near the elbow. When you hit your funny bone, you are hitting the ulnar nerve in the cubital tunnel. It conducted at about 57 m/s, which means I have slight cubital tunnel syndrome.
The coolest part of the test was when the doctor put a needle connected to a computer into muscles in my arm. The needle acted as a microphone and translated the electrical impules in the muscle into noise that was represented as an audio wave on the computer screen. Whenever my muscles were inactive, the wave normally would stay flat--if there were nerve problems, the nerves would incorrectly conduct electrical impulses to the muscles, and there would be noise on-screen when there was no muscle activity.
In a normally-functioning person, the muscles generate noise whenever it's active, which means that whenever I moved my fingers, the screen would explode into an image of a tight audio wave along with loud noise emanating from the computer speakers. Really cool.