Associational therapy was a type of medical treatment sometimes undergone by those who had experienced memory loss. The procedure involved exposing the patient to familiar surroundings in the hope that this would spur the brain's neural synapses into regenerating.
In an illusory future (set in 2383), Doctor Beverly Crusher used this therapy with Commander William T. Riker to attempt to restore his memory, which she claimed had been lost to the effects of result of Altarian encephalitis. (TNG: "Future Imperfect")