Over the years numerous automated registration methods have been developed to quantify locomotory behavior of rats in open fields. These include infrared beam detectors, capacitance plates, balance systems and video systems. The X,Y-coordinates representing the location of the animal at a certain time point have been used to calculate various parameters to quantify and qualify the locomotory pattern. The parameters quantifying the pattern of movement must meet a number of criteria. They must be independent of various aspect of the experimental setup: sampling frequency, spatial resolution of the recording device, shape of the arena, size of animal relative to the arena.

Various parameters obtained by the registration systems described above, have been reported on in literature. These parameters include distance moved, time in zones of the open field, speed of movement and parameters describing the heading of the animal. More complex parameters include fractal dimension, parallelism index [1], temporal and spatial scaling [5], gamma parameter based on a discrete Markov model [4] and various methods to determine the ‘home base’ of an animal [2, 3]. These movement parameters can distinguish the effects of various physiological and behavioral manipulations. Generally these kind of parameters are validated with a number of drugs which modify locomotion, such as amphetamine. The analysis of the open field test is performed in different ways and with different parameters. Some of the conflicting results in the literature could be accounted for by these differences. The effect of these parameters on locomotion in an open field was assessed through a meta-analysis of data from a large number of experiments conducted over the last years at our laboratory. The drugs used in the experiments include NMDA, morphine and PTZ.

References

1. Brudzynski, S.M.; Krol, S. (1997). Analysis of locomotor activity in the rat: parallelism index, a new measure of locomotor exploratory pattern. Physiology and Behavior, 62, 635-642.
2. Cools, A.R.; Heeren, D. (1996). Image-analysis systems for the study of rodent behaviour: spatial and postural transitions of stable configurations in time. Abstr. Measuring Behavior '96 (Utrecht, 16-18 October 1996), 42-44.
3. Eilam, D.; Golani, I. (1990). Home base behavior in amphetamine-treated tame wild rats (Rattus norvergicus). Behavioral Brain Research, 36, 161-170.
4. Mueller, K.; Hollingsworth, E.M.; Cross, D.R. (1989). Another look at amphetamine-induced stereotyped locomotor activity in rats using a new statistic to measure locomotor stereotypy. Psychopharmacology, 97, 74-79.
5. Paulus, M.P.; Geyer, M.A. (1991). A temporal and spatial scaling hypothesis for the behavioral effects of psychostimulants. Psychopharmacology, 104, 6-16.