A novel fully-automated system for lifelong continuous phenotyping of mouse cognition and behaviour

Abstract

Comprehensive ethologically-relevant behavioural phenotyping in rodent experiments is essential for deciphering the neural basis of animal cognition. Automated home-cage monitoring systems present a valuable tool to fulfil this need. However, they often involve complex animal training routines, water or food deprivation, and probe a limited range of behaviours. Here, we present a new fully automated AI-driven home-cage system for cognitive and behavioural phenotyping in mice. The system incorporates spontaneous alternation T-maze, novel-object recognition and object-in-place recognition tests combined with monitoring of an animal position, water consumption, quiescence and locomotion patterns, all carried out continuously and simultaneously in an unsupervised fashion over long periods of time. Mice learnt the tasks rapidly without any need for water or food restrictions. We applied ethomics approach to show that combined statistical properties of multiple behaviours can be used to discriminate between mice with hippocampal, medial entorhinal and sham lesions and accurately predict genotype of Alzheimer disease mouse models on an individual animal level, surpassing the performance of several gold standard cognitive tests. This technology could enable large-scale behavioural screening for genes and neural circuits underlying spatial memory and other cognitive processes.

Designing animal-friendly behavioral tests for neuroscience research: The importance of an ethological approach

“…Indeed, tail lifting, compared with alternative handling methods that do not require tail lifting, increases anxiety in the open-field test (Gouveia and Hurst, 2019) and elevated plus maze (Hurst and West, 2010), and it has been shown to reduce exploratory activity (Gouveia and Hurst, 2017), to increase aversion for the human handler in voluntary interaction test (Hurst and West, 2010) and to impair responsiveness to sucrose reward, indicating a reduction of reward's hedonic value (Clarkson et al, 2018). Several animal-friendly approaches are now available to avoid the negative impact of human handling on mice: (a) adopting non-aversive manual handling techniques, as openhand retrieval through the cupping method (Hurst and West, 2010;Hurst, 2017, 2019;d'Isa et al, 2021b;Davies et al, 2022); (b) employing a tool to handle the mice, as a plastic handling tunnel (Hurst and West, 2010;Gouveia and Hurst, 2013Sensini et al, 2020;Davies et al, 2022); (c) using automated home-cage testing systems in which behavioral outcomes are recorded without physical interaction with the human experimenter (Kiryk et al, 2020;König et al, 2020;Mitchell et al, 2020;Ho et al, 2022;Kohler et al, 2022;Winiarski et al, 2022). Furthermore, not knowing the species-specific characteristics of the studied organism, for example, applying inappropriate motivators, forcing the animal to exhibit behavioral responses it would not normally perform, and measuring the behavior under artificial conditions that do not have much to do with the natural environment in which the animal evolved, all can elevate random error, simply because the individuals tested this way may have to find unique solutions to the problems, considerably increasing individual differences in the study (Gerlai and Clayton, 1999a,b).…”

“…The home-cage is the place where laboratory rodents feel safest and where they are more likely to display spontaneous natural behaviors. Thus, the idea of testing in the home-cage has been gaining considerable attention in the past few years, and several home-cage automated multi-variable recording systems have been developed, e.g., the IntelliCage (Galsworthy et al, 2005 ; Kiryk et al, 2020 ; Iman et al, 2021 ), PhenoMaster (Urbach et al, 2008 ; König et al, 2020 ), Actual-HCA (Bains et al, 2016 ; Mitchell et al, 2020 ) and SmartKage (Ho et al, 2022 ). Automated home-cage testing systems have several advantages: (a) they allow behavioral phenotyping without human interference and without the consequent handling-related stress; (b) the animals are not tested in an external apparatus but in their familiar and well-known housing environment, which eliminates confounds arising from anxiety; (c) data collection is not restricted to a specific moment of the day, but can be performed continuously, 24 h a day, 7 days a week, allowing a more precise and realistic assessment of behavior; d) long longitudinal studies (lasting weeks, months or years), or even life-long studies, can be performed on the same animals with a continuous behavioral assessment, which is particularly relevant for developmental neuroscience and aging neuroscience; (e) interactive elements (e.g., levers, nose-poking ports, motorized doors and running wheels) may be installed in these home-cages, allowing not only detailed motor assessment, but also complex cognitive testing; (f) animals are tested in a natural social context while living together with other conspecifics, thus providing motor and cognitive measurements with a higher ethological validity and allowing additionally to monitor and analyze complex social interactions.…”

“…Indeed, tail lifting, compared with alternative handling methods that do not require tail lifting, increases anxiety in the open-field test (Gouveia and Hurst, 2019 ) and elevated plus maze (Hurst and West, 2010 ), and it has been shown to reduce exploratory activity (Gouveia and Hurst, 2017 ), to increase aversion for the human handler in voluntary interaction test (Hurst and West, 2010 ) and to impair responsiveness to sucrose reward, indicating a reduction of reward's hedonic value (Clarkson et al, 2018 ). Several animal-friendly approaches are now available to avoid the negative impact of human handling on mice: (a) adopting non-aversive manual handling techniques, as open-hand retrieval through the cupping method (Hurst and West, 2010 ; Gouveia and Hurst, 2017 , 2019 ; d'Isa et al, 2021b ; Davies et al, 2022 ); (b) employing a tool to handle the mice, as a plastic handling tunnel (Hurst and West, 2010 ; Gouveia and Hurst, 2013 , 2017 , 2019 ; Sensini et al, 2020 ; Davies et al, 2022 ); (c) using automated home-cage testing systems in which behavioral outcomes are recorded without physical interaction with the human experimenter (Kiryk et al, 2020 ; König et al, 2020 ; Mitchell et al, 2020 ; Ho et al, 2022 ; Kohler et al, 2022 ; Winiarski et al, 2022 ).…”

A multi-disciplinary commentary on preclinical research to investigate vascular contributions to dementia

“…Such detailed datasets can also potentially be combined with a ‘n of 1′ approach, allowing researchers to evaluate the effects of interventions on an individual basis [ 96 ]. By analogy, outcomes in preclinical studies should aim to capture cognition, function, mobility and activities, for example via 24/7 cage-monitoring technology [ 97 ], to provide a more comprehensive profile of the animal's status.…”

ReptiLearn: An automated home cage system for behavioral experiments in reptiles without human intervention

“…These animals can often go without food or drink for extended periods compared to mammals [ 47 , 48 ], potentially reducing their motivation and engagement in behavioral tasks. Moreover, most automated systems employed in mammalian research make use of liquid rewards [ 13 , 17 , 19 ], which are unsuitable for species requiring live prey as a reward. Conversely, reinforcers such as heat can be utilized but are not included in automated behavioral systems.…”