All puppies will have received:

ENS (Early Neurological Stimulation) and ESI (Early Scent Introduction)

This starts on day 3 and goes thru day 16. The ESI helps jump-start the brain since days 3-16 are believed by experts to be a time of rapid neurological growth and development.

Here is a YouTube video demonstrating:
https://www.youtube.com/watch?v=EPQZ2D0AVrQ&t=31s

Here is some AKC data:
https://www.akc.org/expert-advice/dog-breeding/breeder-puppy-socialization-early-neurological-stimulation/