I do it, but only for classes I know I will get an A in. All my classes this semester are BCPM: Astronomy, Inorganic Chem, Biochem, Immunology, Brain Diseases. You should only do this if you have a low BCPM that you are trying to bring up. On AMCAS, the GPAs for each semester are broken down by cGPA, sGPA, and aoGPA so it will be obvious if you purposely overload on BCPM courses.
I would take the physiology/psychology though, it sounds like the biological bases of behavior class at my school.