$1.3 million grant funds clinical trial to test psilocybin for treating patients with phantom limb pain The Psychedelics and Health Research Initiative (PHRI) at UC San Diego has received a $1.3 million grant from the Steven & Alexandra Cohen Foundation to fund a clinical trial investigating the therapeutic potential of psilocybin in treating phantom limb pain. Psilocybin is a naturally occurring psychedelic compound produced by many species of fungus, including so-called "magic mushrooms." Phantom limb pain is pain originating from parts of the body no longer present, such as an amputated arm or leg. It is a form of neuropathic pain that actually originates in the spinal cord and brain.