grey matter vs superbrain

grey matter

noun
  • Brains; a person's ability to think. 

  • A collection of cell bodies and (usually) dendritic connections, in contrast to white matter. 

  • Literal brains as a general substance. 

superbrain

noun
  • An exceptionally powerful brain or artificial intelligence. 

  • An exceptionally intelligent person; a genius. 

How often have the words grey matter and superbrain occurred in a corpus of books? (source: Google Ngram Viewer )