SOUTH SAN FRANCISCO, Calif.--(BUSINESS WIRE)--Vistagen (Nasdaq: VTGN), a late clinical-stage biopharmaceutical company pioneering neuroscience with nose-to-brain neurocircuitry to develop and commercialize a new class of intranasal product candidates called pherines, today announced receipt of a “Study May Proceed” letter from the U.S. Food and Drug Administration (FDA) under its U.S. Investigational New Drug (IND) application for refisolone nasal spray, the Company’s non-hormonal, non-systemic