The Tilonus Institute for Mental Disorders was a hospital for psychiatric patients on the planet Tilonus IV. It had several wards, including Ward 47 and a security ward. This was the only mental health facility on the planet.
In 2369, Commander William T. Riker was kidnapped and subjected to a neurosomatic technique. One of the delusions created by this technique had him believe he was a patient in ward 47 at the Institute.
In the delusion, Doctor Syrus, a psychiatrist there, tried to convince Riker that his being a Starfleet officer was a delusion, just a series of hallucinations that started after he stabbed a man in cold blood. After being given a list of available treatments, Riker opted for reflection therapy. When he was not responding to treatment, the hospital adminstrator Suna ordered synaptic reconstruction on Riker.
While there, he also met a woman named Jaya who also claimed to be a kidnapped Starfleet officer, "Commander Bloom of the starship USS Yorktown". He soon realized that she really was a psychiatric patient however, when she tried to use a spoon as a communicator. (TNG: "Frame of Mind")