- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
A chemical found in the brain of a empath, such as a Betazed, or specie that is capable of telepathy. In 2370, the telepathic demands on Ambassador Lwaxana Troi, while working with the Cairn diplomatic delegation, became so demanding that her psilosynine level became dangerously low.