The Cylinder test is designed to evaluate locomotor asymmetry in rodent models of CNS disorders. As the animal moves within an open-top, clear plastic cylinder, its forelimb activity while rearing against the wall of the arena is recorded. Forelimb use is defined by the placement of the whole palm on the wall of the arena, which indicates its use for body support. Forelimb contacts while rearing are scored with a total of 20 contacts recorded for each animal. The number of impaired and non-impaired forelimb contacts are calculated as a percentage of total contacts. This test is used to phenotype strains of transgenic mice and evaluate novel chemical entities for their effect on motor performance.