I think you are referring to "Fiend Without a Face" which starred Marshall Thompson. Excellent old sci-fi dealing with the effort to materialise thought by using atomic power to boost the brain. This ends up creating some of the most unique and gruesome creatures seen in any fifties sci-fi film. Disembodied brains with spinal cords attached with antennae and small tentacle type legs for movement. Good special effects make this very entertaining.