Classifying postures of freely moving rodents with the help of Fourier descriptors and a neural network

Murine Motion Behavior Recognition Based on DeepLabCut and Convolutional Long Short-Term Memory Network

Murine behavior recognition is widely used in biology, neuroscience, pharmacology, and other aspects of research, and provides a basis for judging the psychological and physiological state of mice. To solve the problem whereby traditional behavior recognition methods only model behavioral changes in mice over time or space, we propose a symmetrical algorithm that can capture spatiotemporal information based on behavioral changes. The algorithm first uses the improved DeepLabCut keypoint detection algorithm to locate the nose, left ear, right ear, and tail root of the mouse, and then uses the ConvLSTM network to extract spatiotemporal information from the keypoint feature map sequence to classify five behaviors of mice: walking straight, resting, grooming, standing upright, and turning. We developed a murine keypoint detection and behavior recognition dataset, and experiments showed that the method achieved a percentage of correct keypoints (PCK) of 87±1% at three scales and against four backgrounds, while the classification accuracy for the five kinds of behaviors reached 93±1%. The proposed method is thus accurate for keypoint detection and behavior recognition, and is a useful tool for murine motion behavior recognition.

MATSAP: An automated analysis of stretch-attend posture in rodent behavioral experiments

Stretch-attend posture (SAP) occurs during risk assessment and is prevalent in common rodent behavioral tests. Measuring this behavior can enhance behavioral tests. For example, stretch-attend posture is a more sensitive measure of the effects of anxiolytics than traditional spatiotemporal indices. However, quantifying stretch-attend posture using human observers is time consuming, somewhat subjective, and prone to errors. We have developed MATLAB-based software, MATSAP, which is a quick, consistent, and open source program that provides objective automated analysis of stretch-attend posture in rodent behavioral experiments. Unlike human observers, MATSAP is not susceptible to fatigue or subjectivity. We assessed MATSAP performance with videos of male Swiss mice moving in an open field box and in an elevated plus maze. MATSAP reliably detected stretch-attend posture on par with human observers. This freely-available program can be broadly used by biologists and psychologists to accelerate neurological, pharmacological, and behavioral studies.

DHA and cholesterol containing diets influence Alzheimer-like pathology, cognition and cerebral vasculature in APPswe/PS1dE9 mice

Cholesterol and docosahexenoic acid (DHA) may affect degenerative processes in Alzheimer's Disease (AD) by influencing Abeta metabolism indirectly via the vasculature. We investigated whether DHA-enriched diets or cholesterol-containing Typical Western Diets (TWD) alter behavior and cognition, cerebral hemodynamics (relative cerebral blood volume (rCBV)) and Abeta deposition in 8- and 15-month-old APP(swe)/PS1(dE9) mice. In addition we investigated whether changes in rCBV precede changes in Abeta deposition or vice versa. Mice were fed regular rodent chow, a TWD-, or a DHA-containing diet. Behavior, learning and memory were investigated, and rCBV was measured using contrast-enhanced MRI. The Abeta load was visualized immunohistochemically. We demonstrate that DHA altered rCBV in 8-month-old APP/PS1 and wild type mice[AU1]. In 15-month-old APP/PS1 mice DHA supplementation improved spatial memory, decreased Abeta deposition and slightly increased rCBV, indicating that a DHA-enriched diet can diminish AD-like pathology. In contrast, TWD diets decreased rCBV in 15-month-old mice. The present data indicate that long-term dietary interventions change AD-like pathology in APP/PS1 mice. Additionally, effects of the tested diets on vascular parameters were observed before effects on Abeta load were noted. These data underline the importance of vascular factors in the APP/PS1 mouse model of AD pathology.

Do rats really express neophobia towards novel objects? Experimental evidence from exposure to novelty and to an object recognition task in an open space and an enclosed space

Three set of experiments were performed in an enclosed space (open-field) and in an open space (elevated platform). The surface of the open-field and the elevated platform were divided in nine equal squares. Rats were exposed (without previous habituation) in a unique session (experiment 1) or three consecutive sessions (experiment 2) either to an open-field (enclosed space) or to an elevated platform (open space) with and without an object on the centre of the field. In experiment 3, rats were exposed (without previous habituation) either to an enclosed or an open space on five consecutive sessions, one session a day. They were tested in an object recognition test in sessions 1, 3 and 5. In sessions 2 and 4, no objects were present. In experiment 1, we recorded the latency, frequency and duration of entries into different areas of the field. In experiment 3, we recorded the latency, frequency and duration of contacts with objects in addition to entries into different areas of the field. The first experiment demonstrates that rats exposed for the first time to an enclosed or an open space do not express neophobia toward novel objects in the absence of walls that surround an open-field. They crossed frequently into and spent more time in areas occupied with an object than in unoccupied areas. After two sessions of habituation to an empty open space or an empty enclosed space, the latency of first approach to a novel object is reduced while the frequency and duration of approaches are increased. The third experiment on object recognition confirmed that rats do not avoid novel objects; they made frequent visit and spent more time in the corner of the field occupied with an object than in empty corners. Recording of crossings provided detailed information about the patterns of exploratory behavior of rats but failed to reveal discrimination between novel and familiar objects which was evident in both open and enclosed space with recording of contacts with objects on the fifth exposure.

Use of artificial neural networks to determine cognitive impairment and therapeutic effectiveness in Alzheimer's transgenic mice

Behavioral testing of transgenic mouse models of Alzheimer's disease (AD) is the functional endpoint for determining the effectiveness of therapeutic interventions and elucidating AD pathogenesis. Utilizing these mouse models, there have been remarkably few attempts to analyze multiple behavioral measures/tasks with higher-level computation techniques, either to distinguish performance between transgenic groups or to reveal any "overall" cognitive benefit of a given therapeutic. The present study compared the classificatory accuracy of artificial neural networks (ANNs) versus more traditional discriminant function analysis (DFA) using multiple behavioral measures/tasks from two AD transgenic mouse investigations. These investigations were to determine if AD transgenic mice could be cognitively-protected by either long-term caffeine administration (CA) or by a cognitively-stimulating environment (SE). Both the entire set of behavioral measures and a subset of 8 cognitive-based measures were analyzed. Both classifiers revealed a beneficial "overall" effect of CA and SE to protect AD transgenic mice across multiple cognitive measures/tasks. However, for both CA and SE datasets, the ANN was superior to DFA for discerning transgenicity (non-transgenic vs. transgenic-controls) across multiple behavioral measures. These results indicate that ANNs have an excellent capacity to discriminate cognitive impairment in AD transgenic mice and thus designate ANNs as a novel, sensitive method for cognitive assessment in Alzheimer's research.

Mice lacking leukocyte common antigen-related (LAR) protein tyrosine phosphatase domains demonstrate spatial learning impairment in the two-trial water maze and hyperactivity in multiple behavioural tests

Leukocyte common antigen-related (LAR) protein is a cell adhesion molecule-like receptor-type protein tyrosine phosphatase. We previously reported that in LAR tyrosine phosphatase-deficient (LAR-Delta P) mice the number and size of basal forebrain cholinergic neurons as well as their innervation of the hippocampal area was reduced. With the hippocampus being implicated in behavioural activity aspects, including learning and memory processes, we assessed possible phenotypic consequences of LAR phosphatase deficiency using a battery of rodent behaviour tests. Motor function and co-ordination tests as well as spatial learning ability assays did not reveal any performance differences between wildtype and LAR-Delta P mice. A spatial learning impairment was found in the difficult variant of the Morris water maze. Exploration, nestbuilding and activity tests indicated that LAR-Delta P mice were more active than wildtype littermates. The observed hyperactivity in LAR-Delta P mice could not be explained by altered anxiety or curiosity levels, and was found to be persistent throughout the nocturnal period. In conclusion, behavioural testing of the LAR-Delta P mice revealed a spatial learning impairment and a significant increase in activity.

Rats and mice share common ethologically relevant parameters of exploratory behavior

Detailed studies of rat exploratory behavior reveal that it consists of typical behavior patterns having a distinct structure. Recently we have developed interactive software that uses as input the automatically digitized time-series of the animal's location for the visualization, analysis, capturing and quantification of these patterns. We use this software here for the study of BALB/cJtau mouse behavior. The results suggest that a considerable number of rat patterns are also present in the mouse. These ethologically-relevant patterns have a significant potential as a phenotyping tool.

Robust tracking and posture description for laboratory rodents using active shape models

We are in the process of developing an automated image analysis system, which uses deformable models of shape, learned from image examples, to interpret video images of rodents. Active shape models provide a compact description of the shape of the animal in a way that enables the postures the differentiate various behaviors to be distinguished. They also model the image profile across the shape boundary. We show how these features allow automatic, robust segmentation of the explicit object of interest. Rather than just detecting movement or changes from background in the image, the system can focus on objects that are of the correct shape and appearance. The modeling of the image profiles also allows the system to distinguish between the actual animal and image artifacts. We show how these techniques are being extended to extract postural information, which can then be integrated with positional data to produce a model of behavior.

EthoVision: a versatile video tracking system for automation of behavioral experiments

The need for automating behavioral observations and the evolution of systems developed for that purpose is outlined. Video tracking systems enable researchers to study behavior in a reliable and consistent way and over longer time periods than if they were using manual recording. To overcome limitations of currently available systems, we have designed EthoVision, an integrated system for automatic recording of activity, movement, and interactions of animals. The EthoVision software is presented, highlighting some key features that separate EthoVision from other systems: easy file management, independent variable definition, flexible arena and zone design, several methods of data acquisition allowing identification and tracking of multiple animals in multiple arenas, and tools for visualization of the tracks and calculation of a range of analysis parameters. A review of studies using EthoVision is presented, demonstrating the system's use in a wide variety of applications. Possible future directions for development are discussed.