dextroamphetamine sulphate: an isomer of amphetamine (trade name Dexedrine) used as a central nervous system stimulant
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
interventricular foramen: the small opening (on both the right and left sides) that connects the third ventricle in the diencephalon with the lateral ventricle in the cerebral hemisphere