Animals were obtained from The Jackson Laboratory and housed for several weeks at BIDMC until they reached ~2 months of age (range from 55 to 62 days). Mice were killed by cervical dislocation and brains were removed and placed in RNAlater for 5 to 10 minutes prior to dissection. Cerebella and olfactory bulbs were removed; brains were hemisected, and both striata were dissected using a medial approach by Rosen that typically yields 5 to 7 mg of tissue per side. The purity of this dissection has been validated by an analysis of acetylcholinestase activity. A pool of dissected tissue from 3 or 4 adults (approximately 25-30 mg of tissue from 6 striata) of the same strain, sex, and age was collected in one session and used to generate cRNA samples. Rought 90 to 95% of all cells in the striatum are medium spiny neurons (Gerfen, 1992, for a review of the structure and function of the neostriatum).

mRNA processing: We used the Amersham Biosciences cRNA synthesis kit protocol.