Mouse Behavior Tracker: An economical method for tracking behavior in home cages

Automated measurement of distance-walked as a "sixth vital sign" for detecting infusion reactions during preclinical testing

Infusion reactions are a major risk for advanced therapeutics (e.g., engineered proteins nanoparticles, etc.), which can trigger the complement cascade, anaphylaxis, and other life-threatening immune responses. However, during the early phases of development, it is uncommon to assess for infusion reactions, given the labor involved in measuring multiple physiological parameters in rodents. Therefore, we sought to develop an automated quantification of rodent locomotion to serve as a sensitive screening tool for infusion reactions, with minimal added labor-time for each experiment. Here we present the detailed methods for building a motion tracking cage for mice, requiring ∼$100 of materials, ∼2 h to build and set up completely, and employing freely available software (DeepLabCut). The distance-walked after injection was first shown to have the predicted effects for stimulants (caffeine), sedatives (ketamine), and toxins (lipopolysaccharide). Additionally, the distance-walked more sensitively detected the effects of these compounds than did pulse oximetry-based measurements of the classical vital signs of heart rate, respiratory rate, and blood oxygen saturation. Finally, we examined a nanomedicine formulation that has been in preclinical development, liposomes targeted to the cell adhesion molecule ICAM. While this formulation has been studied across dozens of publications, it has not previously been noted to produce an infusion reaction. However, the automated motion tracking cage showed that ICAM-liposomes markedly reduce the distance-walked, which we confirmed by measuring the other vital signs. Importantly, the motion tracking cage added < 5 min of labor time per 5-mouse condition, while pulse oximetry with a neck cuff (by far the most stable oximetry signal in mice) required ∼ 100 min of labor time. Thus, automated measurement of distance-walked can indeed serve as a "sixth vital sign" for detecting infusion reactions during preclinical testing. Additionally, the device to measure distance-walked is easy and cheap to build and requires negligible labor time for each experiment, enabling distance-walked to be recorded in nearly every infusion experiment.

Real-Time Void Spot Assay

Normal voiding behavior is the result of the coordinated function of the bladder, the urethra, and the urethral sphincters under the proper control of the nervous system. To study voluntary voiding behavior in mouse models, researchers have developed the void spot assay (VSA), a method that measures the number and area of urine spots deposited on a filter paper lining the floor of an animal's cage. Although technically simple and inexpensive, this assay has limitations when used as an end-point assay, including a lack of temporal resolution of voiding events and difficulties quantifying overlapping urine spots. To overcome these limitations, we developed a video-monitored VSA, which we call real-time VSA (RT-VSA), and which allows us to determine voiding frequency, assess voided volume and voiding patterns, and make measurements over 6 h time windows during both the dark and light phases of the day. The method described in this report can be applied to a wide variety of mouse-based studies that explore the physiological and neurobehavioral aspects of voluntary micturition in health and disease states.

Prolactin-sensitive olfactory sensory neurons regulate male preference in female mice by modulating responses to chemosensory cues

Chemosensory cues detected in the nose need to be integrated with the hormonal status to trigger appropriate behaviors, but the neural circuits linking the olfactory and the endocrine system are insufficiently understood. Here, we characterize olfactory sensory neurons in the murine nose that respond to the pituitary hormone prolactin. Deletion of prolactin receptor in these cells results in impaired detection of social odors and blunts male preference in females. The prolactin-responsive olfactory sensory neurons exhibit a distinctive projection pattern to the brain that is similar across different individuals and express a limited subset of chemosensory receptors. Prolactin modulates the responses within these neurons to discrete chemosensory cues contained in male urine, providing a mechanism by which the hormonal status can be directly linked with distinct olfactory cues to generate appropriate behavioral responses.

Small Animal Video Tracking for Activity and Path Analysis Using a Novel Open-Source Multi-Platform Application (AnimApp)

Experimental biological model system outcomes such as altered animal movement capability or behaviour are difficult to quantify manually. Existing automatic movement tracking devices can be expensive and imposing upon the typical environment of the animal model. We have developed a novel multiplatform, free-to-use open-source application based on OpenCV, called AnimApp. Our results show that AnimApp can reliably and reproducibly track movement of small animals such as rodents or insects, and quantify parameters of action including distance and speed in order to detect activity changes arising from handling, environment enrichment, or temperature alteration. This system offers an accurate and reproducible experimental approach with potential for simple, fast and flexible analysis of movement and behaviour in a wide range of model systems.

Using Looming Visual Stimuli to Evaluate Mouse Vision

The visual system in the central nervous system processes diverse visual signals. Although the overall structure has been characterized from the retina through the lateral geniculate nucleus to the visual cortex, the system is complex. Cellular and molecular studies have been conducted to elucidate the mechanisms underpinning visual processing and, by extension, disease mechanisms. These studies may contribute to the development of artificial visual systems. To validate the results of these studies, behavioral vision testing is necessary. Here, we show that the looming stimulation experiment is a reliable mouse vision test that requires a relatively simple setup. The looming experiment was conducted in a large enclosure with a shelter in one corner and a computer monitor located on the ceiling. A CCD camera positioned next to the computer monitor served to observe mouse behavior. A mouse was placed in the enclosure for 10 minutes and allowed to acclimate to and explore the surroundings. Then, the monitor projected a program-derived looming stimulus 10 times. The mouse responded to the stimuli either by freezing or by fleeing to the hiding place. The mouse's behavior before and after the looming stimuli was recorded, and the video was analyzed using motion tracking software. The velocity of the mouse movement significantly changed after the looming stimuli. In contrast, no reaction was observed in blind mice. Our results demonstrate that the simple looming experiment is a reliable test of mouse vision.

Fast, versatile and quantitative annotation of complex images

We report a generic smartphone app for quantitative annotation of complex images. The app is simple enough to be used by children, and annotation tasks are distributed across app users, contributing to efficient annotation. We demonstrate its flexibility and speed by annotating >30,000 images, including features of rice root growth and structure, stem cell aggregate morphology, and complex worm (Caenorhabditis elegans) postures, for which we show that the speed of annotation is >130-fold faster than state-of-the-art techniques with similar accuracy.

A Review of Freely Available, Open-Source Software for the Automated Analysis of the Behavior of Adult Zebrafish

The analysis of behavior in animal models is an important objective in many research fields, including neuroscience, psychology, toxicology, and neuropsychopharmacology. Animal models have been used for many years, and several behavioral paradigms, such as locomotor activity, social interactions, and cognitive behavior, have been studied in animal models to correlate the behaviors with pharmacological or environmental interventions and with molecular, biochemical, and physiological findings. We reviewed the literature looking for open-source, freely available software to analyze animal behavior and found 12 freely available programs: ToxTrack, EthoWatcher, Mouse Behavior Tracker, Mouse Move, JAABA, wrMTrck, AnimalTracker, idTracker, Ctrax, Mousetracker, VideoHacking, and Cowlog, which were developed with different programs, work on different platforms, and have particular types of inputs and outputs and analysis capabilities. We reviewed some examples of their use, tested some of them, and provided several recommendations for the future development of programs for the automated analysis of behavior in animal models. In conclusion, we show freely available software for the automated analysis of behavior in animal models such as adult zebrafish and provide information for researchers and students looking for quick, easy-to-implement, and inexpensive behavior analysis alternatives.

MouBeAT: A New and Open Toolbox for Guided Analysis of Behavioral Tests in Mice

Animal behavioral tests are essential to understand the bases of neurologic and psychological disorders, which can be evaluated by different methodological and experimental models. However, the quantification of behavioral tests results is limited by the considerable amount of time needed for manual evaluation and the high costs of automated analysis software. To overcome these limitations, we describe here a new, open source toolbox for ImageJ, called Mouse Behavioral Analysis Toolbox (MouBeAT), designed to analyze different behavioral tests in rodents semi-automatically. These tests include Open Field (OF), Elevated Plus Maze (EPM), Y-maze (YM) test and Morris Water Maze (MWM). MouBeAT showed a high correlation with manual evaluation in all the parameters analyzed for all the behavioral tests, reinforcing its value as an accurate analysis tool. This new tool is freely available online.