Phenotyping in Mice Using Continuous Home Cage Monitoring and Ultrasonic Vocalization Recordings

Abstract

Over the last century, the study of mouse behavior has uncovered insights into brain molecular mechanisms while revealing potential causes of many neurological disorders. To this end, researchers have widely exploited the use of mutant strains, including those generated in mutagenesis screens and those produced using increasingly sophisticated genome engineering technologies. It is now relatively easy to access mouse models carrying alleles that faithfully recapitulate changes found in human patients or bearing variants of genes that provide data on those genes’ functions. Concurrent with these developments has been an appreciation of the limitations of some current testing platforms, especially those monitoring complex behaviors. Out‐of‐cage observational testing is useful in describing overt persistent phenotypes but risks missing sporadic or intermittent events. Furthermore, measuring the progression of a phenotype, potentially over many months, can be difficult while relying on assays that may be susceptible to changes in the testing environment. In recent years, there has also been increasing awareness that measurement of behaviors in isolation can be limiting, given that mice attempt to hide behavioral cues of vulnerability. To overcome these limitations, laboratory animal science is capitalizing on progress in data capture and processing expertise. Moreover, as additional recording modes become commonplace, ultrasonic vocalization recording is an appealing focus, as mice use vocalizations in various social contexts. Using video and audio technologies, we record the voluntary, unprovoked behaviors and vocalizations of mice in social groups. Adoption of these approaches is undoubtedly set to increase, as they capture the round‐the‐clock behavior of mouse strains. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Continuous recording of home cage activity using the Home Cage Analyzer (HCA) system Support Protocol: Subcutaneous insertion of a radio frequency identification microchip in the inguinal area Basic Protocol 2: Continuous recording of mouse ultrasonic vocalizations in the home cage.

Identification of Altered Evoked and Non-Evoked Responses in a Heterologous Mouse Model of Endometriosis-Associated Pain

“…For example, behavioral responses may be assessed in an unnatural environment (i.e., animals are isolated, tested out of the cage, social interactions are neglected) involving human contact, which may induce stress, thus increasing the risk of bias and decreasing the quality of the recorded data. To circumvent this limitation, we used an HCA in cage system, which allowed a noninvasive way of observing rodents in their home cages, thereby preserving social interactions and avoiding operator bias [ 26 , 44 ].…”

Measuring Behavior in the Home Cage: Study Design, Applications, Challenges, and Perspectives

“…Rodents display a wide range of ultrasonic vocalizations (USVs) in response to various situations, especially during social interactions (Holy and Guo, 2005;Portfors, 2007;Takahashi et al, 2010). USVs are an important component of a behavioral phenotype (Scattoni et al, 2009;Simola and Granon, 2019;Hobson et al, 2020) and have been successfully used to investigate, among others, communicative deficits in Autism Spectrum Disorder models (Ey et al, 2012;Wöhr, 2014;Ferhat et al, 2016) and age-related degenerative disorders (Menuet et al, 2011).…”

“…Currently, the main challenges are to minimize the effect of USV reflections caused primarily by the cage walls and objects (Hoffmann et al, 2012), improve detection of USVs in noisy recordings (Tachibana et al, 2020) and to relate USVs to individual behavior when animals interact (Vendrig et al, 2019). Hobson et al (2020) provide an example of recording USVs in socially housed mice in an IVC cage. Their system is not designed to determine the identity of the caller, however the use of multiple microphones to triangulate sounds has been shown to provide accurate identification.…”

The Open Field Test

“…Large 6 | P a g e amounts of complex data will require advanced expertise in the dedicated areas of data-mining. For an interesting example of a research project that involves gathering extensive data on the spontaneous behaviour of group-housed mice in the home cage, see [64] and https://www.zooniverse.org/projects/rdot-bains/rodent-little-brother-secret-lives-of-mice/about/research. The successful development of this approach will also depend on sharing the codes and algorithms, validation and standardization of behavioural annotations (for different strains, test environments etc.…”