Conversation so far:
Are there any other interesting aspects about this article?
Pinky (voiced by Rob Paulsen) is another genetically modified mouse who shares the same cage as Brain.
When was it created?
CANNOTANSWER.
Tell me something about Pinky?
Pinky is an extremely unstable and hyperactive mouse.

Question: What is Brain?
Self-contained rewrite: What is Brain in Pinky and the Brain?