Electrifying a teacher!

10 October 2010




This one is really painful and shouldn't be done at home.



We got a teacher and applied some electricity.







We got a teacher to roll up their sleeve.



We applied a small 20 mAmp electrical current to the funny bone, also called the olecronon


See movie below for the result






The hand muscle twitched. Uncontrollably. Repetitively. And causing some pain.



Increasing the current applied caused the muscle twitching to become more vigorous, more frequent and also resulted in a more pained expression on the face. 



Leaving the electrical stimulator on for a few minutes increased the force of the muscle twitching. Causing more pain.



However, if we increase the current even further the muscle will eventually 'stop listening' and stop moving. We won't do this though as it would be very painful and a little dangerous.











Which part of the brain is involved?


The motor cortex and the ulna nerve.


Why is this happening?


This happens because the nervous system uses electricity as it's method of communication, to process information and also direct our muscles to move, as you can see in this video:





In this experiment we applied electricity directly to a nerve fibre called the ulna nerve, just beneath the funny bone. Your ulnar nerve runs all the way from the shoulder to your little finger, and is made up of motor nerve cells. These nerve cells carry information from your brain to your muscles, and they carry the information as electricity.



Usually your hand muscles are controlled by the motor cortex, a part of the brain running like a strip over the head from one ear, to the other.



To move your little finger the motor cortex initiates an electrical signal which then passes to a bundles of nerves in the body called the ulna nerve. This nerve cable runs all the way from your shoulder to your wrist. The nerve sends the electrical current via an action potential.



Once the electric signal reaches the wrist it discharges a little chemical , or neurotransmitter, called acetylcholine. This causes electrical activation of the muscles below your little finger, you hypothenear muscles. This electrical signal causes the muscle fibres, which make up the hypothenear muscle, to contract and relax in rapid succession causing the twitch.



By applying electricity directly to the ulna nerve fibre at the funny bone we are stimulating the nerves downstream of the motor cortex. The brain has been bypassed!



Increasing the current of the electrical stimulation applied at the ulna nerve increases the flow of electrical charge travelling up the ulna nerve. This increases the signal received by the muscles in the hand, and the muscle responds to the increased current by the hand twitching more vigorously and with more force. This also leads to a more pained expression on the teacher.



If you leave the electrical signal applied to the ulna nerve for a long time more and more muscles fibres will be recruited for activation and contraction. This recruitment of neighbouring muscle cells over time will increase the force of the twitching.



If you increase the frequency of the electrical signal even further, eventually it will stop having an effect as the nerve cells start getting used to the electrical signal and start to just ignore it.


Why are neuroscientists so very excited about this?

This is a brilliant example of how we can activate our nerve cells and muscles in the body with electricity! In certain people this process can go wrong though. For example, how many bananas did Peter Andre use to eat? An excessive 50 a day. He overdosed on the yellow bad boys.

common form of eating a bananaBananas are usually pretty healthy things to eat, but not that many! They contain a lot of potassium, the charged molecule that nerve cells use to make electrical activity. And so Peter Andre, by eating about 50 bananas a day overdosed on potassium, causing his body to be flooded with potassium ions, messing up his nerve cell electrical activity and causing his muscles to seize up giving him temporary paralysis. Thankfully, he has since  recovered. The excess potassium is now out of his system, his muscles and nerve cells are functioning as they were. And he doesn't eat so many bananas these days.

Potassium not only communicates electrical activity in nerve cells in the body, but is also used in the brain.  And so scientists are looking at drugs that affect these ions to help treat people who have conditions like schizophrenia, to help activate certain areas.

Scientists are also burying smaller versions of these electric shock panels that were placed on the teacher's funny bone, in people's brains. They are treating people with really bad cases of depression, heroin addiction and obsessive compulsive disorder in this way. People opting to have this treatment have surgery to open up their skulls, and doctors insert the little shock panel into a specific region of the brain called the nucleus accumbens. This is a really small part of the brain, right in the middle, which is involved in reward and feeling pleasure. The surgeons carefully place the electric device there, then stitch the scalp back up and send little pulses of electricity to the people's brains. And this instantaneously switches off their symptoms! The power of electricity!

The Risky Part: what to be aware of and how to keep the science safe:




Risk to Audience

Risk to Presenter

Control Measures

Residual Risk to Audience

Residual Risk to Presenter

Do not try this at home. This experiment was done using a very low current. Mains electricity would be extremely dangerous




20 mA



















Add a comment