The “mouse activity centre”:
a new method for analysing spontaneous and running wheel activity in mice
D. Surjo1, S.S. Arndt1, F.J. van der Staay1, U. Baumann2 and O. Huettmann2
1Anatomy II, Cognitive Neurobiology, University of Cologne, Cologne, Germany
2Munich, Germany
In the field of chronobiology, measurements of spontaneous and running wheel activities are typical methods used to analyse the function of the biological clock in rodents. However, both measurements are rarely performed simultaneously, because signal discrimination is problematic and the two activities are often mistaken for representations of general activity. Passive infrared detectors, for example, are unable to determine whether a signal occurs inside or outside a running wheel, as they cannot distinguish between the two signals. Only by compartmentalizing the observation cage into sections can the signals be separated. Spontaneous or general activity, detected by an infrared sensor, reflects a multitude of behaviors, such as running, rearing, leaning, climbing, feeding and drinking. In contrast, running wheel behavior reflects one form of activity. It has been hypothesised that wheel running represents the search by an animal for potential resources where the goal is not perceivable.
Our primary aim was to develop a data acquisition system that ensures stable performance and allows a high resolution of data acquisition and storage. The system we have developed enables the data acquired to be checked without disturbing the animals or interfering with the data acquisition process.
Short description of the system
Signal detection is based on a passive infrared sensor (PIR), which captures locomotor activity, and a Hall sensor, which registers the running wheel rotations. The PIR sensor is mounted at the top of the cage, while the Hall sensor is placed by the outside of the wheel. An integrated processor facilitates signal processing, transformation, timing coordination and discrimination of the sensor signals. The 'activity centre' enables the simultaneous observation of both spontaneous and running wheel activity in 48 cage units. The data can then analysed with appropriate software.
The system will be presented, and preliminary data collected with it will be shown.
Paper presented at Measuring Behavior 2002 , 4th International Conference on Methods and Techniques in Behavioral Research, 27-30 August 2002, Amsterdam, The Netherlands