In studies on rodent behavior, the available image-analyzing systems usually reduce the subject (rodent) to a single spot and provide its x and y coordinates: then, the distance, duration and velocity of the moving spot in space is calculated. In 1996 we have presented two new systems, including computer programs that provide quick, objective and new measures of the animal's progression in space [1]. The first, more classic system allowed a computerized and automated analysis of behavior on the open field, elevated plus maze and Morris water maze. Furthermore, the newly developed computer program allowed a quantitative objective and detailed analysis of exploratory behavior in a novel environment according to the rules of "home base behavior" as described by Eilam [2]. The second, more sophisticated system (CCD camera; video processor: Fast FPS60; computer: Pentium, Windows 95) allowed the computerized and automated measurement of lateral movements of the head, head-torso and head-torso-pelvis of freely moving rats [1].

We will now present an extension of the latter system. It allows a computerized and automated analysis of lateral, horizontal and vertical movements of the freely moving rat in space. The extended system has at least two broad applications. First, it allows a quantitative, automated analysis of distinct behavioral items. At the moment, we are able to distinguish items such as "head grooming", "torso grooming" and "genital grooming"; in addition, we are able to distinguish distinct postures such as "sitting", hunch back", "curved", "attend" and "stretched attention". When combined with the program that allows analysis of the animal's progression in space, the system allows a quantitative and objective analysis of nearly the entire behavioral repertoire. Second, the system allows a quantitative and objective analysis of the "Mobility Gradient" as described by Golani et al. [3]. This Mobility Gradient is an extremely useful tool in studies on ontogeny, ageing, drug-induced changes and recovery from brain damage.

References

1. Cools, A.R.; Heeren, D. (1996). Image-analyzing systems for the study of rodent behavior: spatial and postural transitions of stable configurations in time. Abstr. Int. Workshop on Methods and Techniques in Behavioral Research (Measuring Behavior '96: Utrecht, The Netherlands), 42-44.
2. Eilam, D. (1997). Postnatal development of body architecture and gait in several rodent species. Journal of Experimental Biology, 200, 1339-1350.
3. Golani, I.; Benjamini, Y.; Eilam, D. (1993). Stopping behavior: constraints on exploration in rats (Rattus norvegicus). Behavioral Brain Research, 53, 21-33.