Automated multivariate measurement of spontaneous motor activity in mice: time course and reliabilities of the behavioral measures.

A variety of automated procedures have been developed to measure certain aspects of spontaneous motor activity in small animals. The present study used a Digiscan Animal Activity Monitor to measure six different aspects of spontaneous motor behavior in male CF-1 mice. The Digiscan system uses infrared beams and computer analysis to quantify various behavioral variables. The mice were tested for 1 hour on 2 different days of the week for 3 consecutive weeks. Both the temporal changes in the measured variables and the test-retest reliabilities were examined in a group of 30 mice. Statistical analysis of the data revealed significantly higher mean values for total movement time, average distance travelled, and horizontal activity on the first test session relative to the second session (p less than 0.01). The other 3 measures, total distance travelled, number of movements, and average speed, did not vary significantly across test sessions. All 6 behavioral variables showed good test-retest reliabilities and these could be increased by aggregating the data on a weekly basis. The present results indicate that the measures obtained from the Digiscan system are reliable and that the animals should first be habituated to the test apparatus in order to obtain stable baseline activity values.