An improved procedure for integrated behavioral z-scoring illustrated with modified Hole Board behavior of male inbred laboratory mice

Abstract

Background: Guilloux et al. introduced: integrated behavioral z-scoring, a method for behavioral pheno-typing of mice. Using this method multiple ethological variables can be combined to show an overall description of a certain behavioral dimension or motivational system. However, a problem may occur when the control group used for the calculation has a standard deviation of zero or when no control group is present to act as a reference group. New method: In order to solve these problems, an improved procedure is suggested: taking the pooled data as reference. For this purpose a behavioral study with male mice from three inbred strains was carried out. The integrated behavioral z-scoring methodology was applied, thereby taking five different reference group options. The outcome regarding statistical significance and practical importance was compared. Results: Significant effects and effect sizes were influenced by the choice of the reference group. In some cases it was impossible to use a certain population and condition, because one or more behavioral vari-ables in question had a standard deviation of zero. Based on the improved method, male mice from the three inbred strains differed regarding activity and anxiety. Comparison with existing method: Taking the method described by Guilloux et al. as basis, the present pro-cedure improved the generalizability to all types of experimental designs in animal behavioral research. Conclusions: To solve the aforementioned problems and to avoid getting the diagnosis of data manipula-tion, the pooled data (combining the data from all experimental groups in a study) as reference option is recommended.