The Mimetic thought processor was a device used by the Stragoth to read the mind of the people captured and brought through the Scanning device, itis used in conjunction with a mimetic imaging device.
By attaching an activated mimetic thought processor to the temple, the device connected the mind of the user to the person the passed through the Scanning device and encased inside a cocoon shaped device. The device only works with those inside the cocoons. If the person inside the cocoon is interrupted it creates a disturbance in the connection between the two people. (SG1: "Foothold", "Smoke and Mirrors")
The Mimetic thought processor was first used by the race known as Stragoth to gain a foothold in Stargate Command. Thanks to this device and the mimetic imaging device they were able to imitate nearly every person on the base and they also planned to take over The Pentagon. Their plan was however thwarted by Major Samantha Carter. (SG1: "Foothold")