Comparative analysis of research behavior of laboratory mice and wild rodents in standard and enriched versions of the open field task

Exploratory activity is a vital form of behavior influenced by the habitat and individual experiences of animals. To assess the roles of these factors, we studied exploratory behavior in an identical setting among three rodent species that differ in their ecological niches, navigation characteristics, and levels of individual experience: wild animals from natural populations — bank voles (Clethrionomys glareolus) and the herb field mouse (Sylvaemus uralensis)—and C57BL/6J laboratory mice. Exploratory behavior was measure in a standardized open field test. To evaluate the influence of environmental novelty, animals had four sessions of empty open field exploration explored followed by four sessions in an enriched open field. Expert annotation of the behavioral patterns revealed that the animals engaged in 11 specific behavioral acts to explore the empty arena and 22 types of acts in the enriched arena. Notably, we identified specific behavioral acts in either wild rodents or laboratory mice. Bank voles displayed significantly less exploratory activity compared to the mouse species, which showed only slight differences in exploratory behavior. A key factor influencing the exploratory activity of the compared species was the enrichment of the arena with objects. The addition of objects not only increased the overall exploratory activity of the animals but also altered the structure of their exploratory behavior. Contrary to the initial hypothesis, the factor of environmental novelty had the least influence on behavior, with effects varying depending on specific behavioral forms and manifesting only in combination with other factors. The results reveal complex and nonlinear relationships among the factors determining rodent behavior in the open field task, which should be considered in analyzing the neural bases of this behavior and interpreting exploratory behavior in natural conditions.