The earliest recorded human effort at neuro-stimulation appears to have been that of the Mesopotamian healer Scribonius Largus 47AD (?) who used electrical currents to produce transient pain relief.
By either the direct application of electrical torpedo fish (eels, of the type shown below) to the human body or by placing painful extremities into a pool of water containing torpedo fish the resulting electrical shocks stunned the nervous system allowing an immediate and residual numbness in the extremity.
In this application electrical torpedo fish were the very first means of achieving transcutaneous electrical nerve stimulation (TENS) for therapeutic purposes. This form of treatment was particularly popular for the treatment of gouty arthritis.
Pliny (AD 61-113) commented on the fact that while the torpedo fish was not itself sluggish, it could induce sluggishness in other fish. He also detailed how to extract the medicinal magic of the torpedo fish into oils and ointments used for various ailments, or more popularly either to cool lust or to induce love.
In Plato’s (428-348 BC) dialoge Meno Socrates is told “you seem both in appearance and in your power over others to be like a torpedo fish, who torpifies those who come near him, as you have now torpified me, I think. For my soul and my tongue are really torpid and I do not know how to answer you.”
The affects of a shock from the electric Torpedo Fish, which lived in the Mediterranean, were well known. What caused of the affects was not. Aristotle (384-322 BC) said that the torpedo fish “narcotize” its prey.