The Babinski Reflex, also known as the Plantar Reflex, is a physical reflex shown when the bottom of the foot is stimulated by having a blunt instrument, i.e. tongue depressor, run across it. The normal response to this type of stimulation is a downward flexion of the big toe. An upward flexion can be a sign of disease of the brain or spinal cord. This test was named for the French physician and neurologist, Joseph Babinski, who first documented it.