Automated Video-Image Analysis of Behavioral Asymmetries

Abstract

The analysis of behavioral asymmetries is a widely employed approach to investigate behavior in relation to functions of the brain. Out of the repertory of presently available measures, turning behavior is probably the one that has been examined the most. Spontaneous or conditioned turning may be used either as an independent variable to look for related asymmetries in the brain, or turning may be analyzed dependent on stimulation (electrical, chemical) or lesion of the nervous system (for reviews, see Pycock, 1980; Pycock and Kilpatrick, 1989; Miller and Beninger, 1991). One of these lesion techniques is almost inevitably associated with the analysis of turning behavior, namely the unilateral 6-hydroxydopamine (6OHDA) lesion of the nigrostriatal dopamine (DA) system, which serves as a unilateral model of Parkinson’s disease. Here, the study of turning behavior has provided substantial information about the role of the basal ganglia, the neurotransmitters involved, and mechanisms of functional recovery. Turning behavior has also been used for screening of potential therapeutic drugs and the study of possible neurotrophic factors or of brain grafts. Different kinds of methods (e.g., rotometers) are available to measure turning, and out of these, the automated analysis of video images is the most recent and probably the most promising. With this approach, not only turning, but also thigmotactic scanning, another potential measure of behavioral asymmetry, can be evaluated automatically. This method will be explained in the following, and its applicability will be demonstrated by several experimental examples.