A neuron refractor is a large device capable of extracting a Cybertronian's mind and placing it into the brain of a human or vice versa. A transplanted Cybertronian mind has access to the human's senses, but is incapable of controlling their body, while a human mind in a robot body has full use of its new form. The machine was developed by Knock Out.
After developing the device, Knock Out and some Vehicons set it up in Zhejiang Province, China and captured a human worker from a scrap-metal facility to use as a subject. When Optimus Prime came to investigate energon readings, Knock Out used the neuron refractor to zap the Autobot's mind into the human, leaving a metal shell to be fed into the crusher. Optimus, though helpless in the human body, found he could mentally communicate with the host mind, and helped Lin-Che operate the machine. It was thus utilized to return Optimus's mind to his own body in time to punch out Knock Out.
MECH Agent Novo discovered the machine when he scouted the area to investigate the recent activities, and recognized it as a machine able to transfer minds. He was interrupted by Bulkhead and Bumblebee arriving to take the refractor back to base, and hid inside the machine. After the two Autobots had retrieved the neuron refractor, Novo downloaded its schematics and then escaped from the Autobot base. With the information he'd gathered, MECH's technicians were able to build a duplicate device and use it to transfer Novo's mind into a mechanical body. Novo, having a change of heart about the whole evil organisation thing, subsequently destroyed MECH's refractor.