[A metrical analysis of exploratory behavior in mice: effects of methamphetamine and diazepam (author's transl)]

Exploratory behavior can be considered a kind of positional behavior. The theory for the analysis of exploratory behavior by the presented method is based on the concept of the Markov process. The following parameters were used in this experiment; (1) frequency of visits to all the positions that are unit spaces expedient to the observation (N), (2) Entropy (HI), a measure of the spacial distribution of animal location, (3) Entropy (HII), a measure of the degree of disorder in movement direction, and (4) length of the longest path passed frequently (L), calculated by examining an upper confidence limit for a parameter of a binomial distribution. Both methamphetamine and diazepam increased N at lower doses, and increased L dose-relatedly. Methamphetamine decreased the values of HI and HII. Diazepam increased HI value while decreased HII value. These results indicate that the effect of methamphetamine on the exploratory behavior in mice is to narrow their behavior space and to make their movement pattern monotonous, back and forth within a small area (i.e. stereotyped behavior), and the effect of diazepam is to extend their behavior space and also simplify their movement pattern, going round and round over a wide area in the apparatus. The results of this experiment suggest that the present method is useful for analysis of exploratory behavior and a better understanding of the effects of psychotropic drugs.