• mice exhibit normal social and circadian behaviors (J:158611)

• mice exhibit a 40 minute delay in D-amphetamine-induced hyperlocomotion compared with similarly treated wild-type mice

• D-amphetamine-treated mice exhibit a dose dependent suppression of vertical activity unlike similarly treated wild-type mice that exhibit an increase in vertical activity

• in a dark-light choice test, mice exhibit increased rearing in the light compartment compared with wild-type mice

• in an elevated place maze, mice spend more time in the open arms than wild-type mice

• in a novelty suppressed feeding paradigm, mice exhibit shorter latency to feeding compared with wild-type mice

• however, mice exhibit normal anxiety-related behavior in an open field, forced swim, and tail suspension tests

• mice exhibit a 40 minute delay in D-amphetamine-induced hyperlocomotion compared with similarly treated wild-type mice

• D-amphetamine-treated mice exhibit a dose dependent suppression of vertical activity unlike similarly treated wild-type mice that exhibit an increase in vertical activity

• in an open field test, mice exhibit increased horizontal and vertical activity compared with wild-type mice

• increased activity begins at 6 weeks of age and persists at least until 16 months of age

• however, treatment with methylphenidate or haloperidol decreases activity levels

• in an open field test, mice exhibit increased vertical activity compared with wild-type mice

• increased activity begins at 6 weeks of age and persists at least until 16 months of age

• however, treatment with methylphenidate or haloperidol suppresses vertical activity

• in an open field box, mice fail to build a nest unlike wild-type mice

• protein expression of dopamine receptors 1 and 2 and NMDA receptors are decreased in the striatum compared to in wild-type mice

• MK801-treated mice exhibit a more rapid onset of increased horizontal activity and decreased vertical activity compared with similarly treated wild-type mice