Stereotypy and asymmetry in mice

Mice ran in a circular runway. Number and direction of circuits were recorded. Most control mice ran about the same number of circuits in each direction. After 100 mumols/kg cocaine there were 3.5 times as many circuits and most mice ran most circuits in one direction. Some mice ran strongly in one direction after a first dose of cocaine and strongly in the other direction after a second dose. Hence, the primary influence toward unidirectional running is stereotypy rather than asymmetry.