A simple, inexpensive rotometer for automatically recording the dynamics of circling behavior.

An inexpensive, automated system for recording circling behavior in small animals is described. The apparatus provides information concerning: left and right full (360 degrees) rotations, half (180 degrees) turns, the time it takes for a rotation, the number of consecutive rotations in each direction, reversals (180 degree changes in direction), net rotations which are displayed directly without a source of electrical power, plus other parameters of circling behavior. The system is simple in principle and construction, and is virtually maintenance free. Depending on the options desired, a single rotometer can be built for approximately $350 or less than $70 by anyone able to use basic hand tools.