Neural stimulator on Spock.
Remote control for a neural stimulator.
A 24th Century neural stimulator.
The neural stimulator was a medical instrument used to increase neural activity in a humanoid brain. 23rd century devices of this sort were often larger than their 24th century counterparts.
Dr. McCoy used one to give Spock's body life support and motion after his brain had been stolen by the Eymorgs. These devices could be operated by remote control, if neccessary. (TOS: "Spock's Brain)."
Dr. Crusher used a neural stimulator in an attempt to revive the fatally injured Natasha Yar after she had been attacked by Armus. (TNG: "Skin of Evil").
Professor Berlinghoff Rasmussen stole a neural stimulator, in an attempt to sell the technology in the 22nd century. (TNG: "A Matter of Time").
Ensign Nog used several neural stimulators to make the Vorta Keevan seem alive long enough to make a prisoner exchange for Ishka. (DS9: "The Magnificent Ferengi").