A refined behavioral analysis for the genetic dissection of food exploration strategies in mice

A. de Mooij-van Malsen¹, B. Olivier^1,2, B. Spruijt³, J. van Ree¹ and M. Kas¹

¹Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Utrecht,The Netherlands
²Department of Psychopharmacology, University Utrecht, Utrecht, The Netherlands
³Department of Animal, Science and Society, University Utrecht, Utrecht, The Netherlands

In nature, an animal must, in order to survive, establish a balance between finding new resources and protecting itself from threatening situations. Conventional laboratory tests for exploration strategies reveal marked behavioural differences between different inbred strains of mice. Although these behavioral differences reflect genetic variation, the nature of these tests makes it difficult to interpret the behavioral variation. Therefore, we introduce a novel behavioral phenotyping method that dissects the composition of exploration strategies by assessing behaviors directed at obtaining food (approach) and the innate preference to shelter (avoidance).

Conventional tests for exploration strategies, such as the elevated plus maze and open field, have limitations. They are usually short-lasting and the animal’s performance in these tests is confounded by motor activity levels and novelty-responsiveness. For these reasons, we have developed a home cage environment (PhenoTyper^® PT10S/P /N Version 1.01, Noldus Information Technology bv, The Netherlands) that dissociates avoidance and approach behavior regardless of individual motor activity levels. Combined with the EthoVision^® (Noldus Information Technology bv, The Netherlands) video-tracking system mice can be monitored for several days. In this way, novelty-induced, baseline and circadian behavioral variation can be studied without experimenter interference.

Characterization of a panel of chromosome substitution strains (CSS) in this Modi.ed Homecage Environment (MHE) introduces a simple and powerful genetic strategy for identifying quantitative trait loci affecting different behavioural processes. Each CSS carries a single chromosome substituted from a donor strain (A/J) onto a common host background (C57BL/6J), strains that exhibit marked physiological and behavioral differences

In our initial studies, different CSS showed distinct behavioral phenotypes in the MHE. Since distinct CSS were found that affected either motor activity levels or shelter preference, these data show that continuous multi-day recordings in designed environments can dissociate complex behaviors into refined behavioral components that involve physiological processes with different genetic origin.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.

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