A newly discovered molecular mechanism helps control the amount and effectiveness of a substance that mimics an active ingredient in marijuana, but that is produced by the body's own nerve cells. Cannabinoid signaling systems are common throughout the body and affect a variety of functions. Developing new therapies that modulate these molecular communications might help patients with autoimmune or neurological disorders, including brain inflammation following a viral infections. Specifically targeted treatments would have medicinal benefits without mind-altering side effects.