A stereoscopic camera is provided comprising: an image sensor ; a lens system adapted to focus light from a scene onto the image sensor ; a dividing device associated with the lens system for dividing the lens system into two portions; and a structure associated with the lens system defining an aperture limiting an amount of light passing through at least a portion of the lens system. Information is recorded in the first group unit. A remedy for polyglutamine disease is screened by administering a test substance to this nonhuman animal and examining changes in its conditions or pathological findings.