Many of the behavioral parameters exhibited by an organism show daily fluctuations. These may persist under constant environmental conditions, demonstrating that they are governed by an endogenous (circadian) clock. The monitoring of locomotor activity in rodents is probably one of the most common methods to track this endogenous timing system. The analysis of locomotor activity rhythms can provide several parameters that may be used to describe the status of this endogenous clock. In the past few years several companies have developed hardware and software systems that allow the collection and the analysis of activity data using a personal computer.
