Encephalograph
In the script of the  first season episode , an encephalograph is a device used for scanning a humanoid's brain.

When Spock noticeably began to detect an unusual reading on the 's bridge (later identified as being the planet Gothos), Dr. McCoy reacted by asking him if there was "a squiggle on your encephalograph".

See also 
 Electroencephalography
 Encephalographic polygraph scan
 Encephalographic profile
 Hyperencephalogram

External link 

Unused production material