Piccinini seems to have gone insane from being in the lab working with rats all day, with one of his personal archives being "Shriek and squeals are all I hear, my dreams are infested with these rats."
He also saw himself as a god to the rats with more of the archive saying "If they knew that and had the capacity to, they would respect me. But no! It's nothing but screams and wailing!"
It seems that the screams were in his head, due to him saying he could never escape the shrieks.
Piccinini is the creator of one of the boss enemies in the game, that being Sotiris. He also is a note writer and an object in the game that is needed for the Nightmare Ending.
Spoilers for Nightmare Ending here
- Piccinini may have been told by Bayagototh to make Sotiris.