PhenoWorld: a new paradigm to screen rodent behavior

Abstract

Modeling depression in animals has inherent complexities that are augmented by intrinsic difficulties to measure the characteristic features of the disorder. Herein, we describe the PhenoWorld (PhW), a new setting in which groups of six rats lived in an ethological enriched environment, and have their feeding, locomotor activity, sleeping and social behavior automatically monitored. A battery of emotional and cognitive tests was used to characterize the behavioral phenotype of animals living in the PhW and in standard conditions (in groups of six and two rats), after exposure to an unpredictable chronic mild stress paradigm (uCMS) and antidepressants. Data reveal that animals living in the PhW displayed similar, but more striking, behavioral differences when exposed to uCMS, such as increased behavioral despair shown in the forced swimming test, resting/sleep behavior disturbances and reduced social interactions. Moreover, several PhW-cage behaviors, such as spontaneous will to go for food or exercise in running wheels, proved to be sensitive indicators of depressive-like behavior. In summary, this new ethological enriched paradigm adds significant discriminative power to screen depressive-like behavior, in particularly rodent's hedonic behavior.

Social interactions impact on the dopaminergic system and drive individuality

“…Social life in natural environments and its consequences on the development of individuality cannot be easily addressed in standardized behavioral laboratory tests. Advances in automatic behavior analysis opens up new opportunities for in-depth phenotyping 18 – 20 and for studying individuation in the laboratory 12 . An essential benefit of automation is the ability to conduct experiments on timescales that are orders of magnitude longer than traditional experiments (from minutes in classical assays to months of observation in automated systems).…”

“…Social interactions markedly influence a number of behaviors 17 , 31 , yet how they affect the development of inter-individual variability has rarely been addressed in standardized tests. Numerous studies emphasize the need to use large social housing environments, with automatic testing 20 , 32 – 35 . Such environments have up until now been mainly used to evaluate strain differences 18 , 19 or test the effect of specific perturbations such as stress on subgroups 20 .…”

“…Numerous studies emphasize the need to use large social housing environments, with automatic testing 20 , 32 – 35 . Such environments have up until now been mainly used to evaluate strain differences 18 , 19 or test the effect of specific perturbations such as stress on subgroups 20 . An essential benefit of automation is that it challenges the classical paradigms consisting in the analysis of average behaviors in distinct groups of animals observed on a short timescale, and puts forward the statistical analysis of individuals recorded in an ecological situation over long timescales.…”

“…The reward value of the bottle content could be changed, to evaluate whether mice were able to track the highest reward. Such automation of the task, by minimizing handling and the presence of the experimenter, prevents most limitations of human assessment (i.e., cost and time) and eliminates the risks of stress or disturbance of the animal natural cycle 20 , 33 , 34 , 49 . Simple rules were used to automatize the test.…”

Animal models in psychiatric research: The RDoC system as a new framework for endophenotype-oriented translational neuroscience

“…This also claims for more complex and labour-intensive models. For instance, social interaction behaviour can now be observed 24 h a day using « PhenoWorld» (Castelhano-Carlos et al., 2014, Hong et al., 2015, Shemesh et al., 2013). Accurate assessment of cognitive function requires a touch screen approach, which is time consuming and apparatus-demanding (Romberg et al., 2013).…”