I seem to recall that Kesey was undergoing the gov't "research" around the same time as Robert Hunter in the same facility. That may just be legend, though.
Yes, they both were a part of the MK-Ultra program ran by the CIA at Stanford.
# Merry Prankster Ken Kesey, author of One Flew Over the Cuckoo's Nest, volunteered for MKULTRA experiments involving LSD and other psychedelic drugs at the Veterans Administration Hospital in Menlo Park while he was a student at nearby Stanford University. Kesey's experiences while under the influence of LSD inspired him to promote the drug outside the context of the MKULTRA experiments, which influenced the early development of hippie culture.
# Robert Hunter is an American lyricist, singer-songwriter, translator, and poet, best known for his association with Jerry Garcia and the Grateful Dead. Along with Ken Kesey, Hunter was an early volunteer MKULTRA test subject at Stanford University. Stanford test subjects were paid to take LSD, psilocybin, and mescaline, then report on their experiences. These experiences were creatively formative for Hunter:
Sit back picture yourself swooping up a shell of purple with foam crests of crystal drops soft nigh they fall unto the sea of morning creep-very-softly mist...and then sort of cascade tinkley-bell like (must I take you by the hand, every so slowly type) and then conglomerate suddenly into a peal of silver vibrant uncomprehendingly, blood singingly, joyously resounding bells....By my faith if this be insanity, then for the love of God permit me to remain insane.