All animals were raised at Beth Israel Deaconess Medical Center in SPF facilities from stock obtained from either Jackson Laboratory or UTHSC. All mice were killed by decapitation. Whole brain dissections were performed at Beth Israel Deaconess Medical Center by Glenn Rosen and colleagues. Neocortex samples were close to complete but are likely to include variable amounts of underlying white matter. Samples may also include parts of the pyriform cortex and subiculum.

All animals used in this study were either 3 or 14 days of age. A pool of dissected neocortical tissue from three naive animals of the same strain and age were collected in one session and used to generate RNA samples. The great majority (75%) of animals were sacrificed between 9:30 AM and 11:30 AM. All animals were sacrificed between 9 AM and 5 PM during the light phase. All RNA samples were extracted at Beth Israel Deaconess Medical Center by Glenn D. Rosen and colleagues.