Brain Dead (1990)

Dr. Rex Martin is a leading neurosurgeon specializing in the cerebral misfunctions that cause mental illnesses, whose expertise is called up by an old school chum, Jim Reston, who is now part of the mega-corporation Eunice. Reston needs Dr. Martin's help in extracting crucial data from the mind of John Halsey, once a top mathematician at Eunice, now a paranoid at the local asylum. Can Dr. Martin help both Halsey and his friend, or is he getting caught up in a corporate nightmare from which he may never escape?—EllenRipley112