1. A method comprising the steps of: (a) administering to a mammal an effective amount of a pharmaceutical agent which inhibits Gpr12 activity in the mammal; (b) providing training to the mammal under conditions sufficient to produce an improvement in performance by the mammal of a cognitive task; (c) producing a long-lasting performance gain in the mammal relative to the performance of said cognitive task achieved by training alone; wherein said pharmaceutical agent comprises an effective amount of a Gpr12 siRNA molecule or an effective amount of a biologically active Gpr12 antisense fragment.