Long-term monitoring of huddling behavior in mice using online image processing

Many animal species, including mice, form societies of numerous individuals for survival. Understanding the interactions between individual animals is crucial for elucidating group behavior. One such behavior in mice is huddling, yet its analysis has been limited. In this study, we propose a cost-effective method for monitoring long-term huddling behavior in mice using online image processing with OpenCV. This method treats a single mouse or a group of mice as a cluster of pixels (a 'blob') in video images, extracting and saving only essential information such as areas, coordinates, and orientations. This approach reduces data storage needs to 1/200000th of what would be required if the video were recorded in its compressed form, thereby enabling long-term behavioral analysis. To validate the performance of our algorithm, ~2000 video frames were randomly chosen. We manually counted the number of clusters of mice in these frames and compared them with the number of blobs automatically detected by the algorithm. The results indicated a high level of consistency, exceeding 90% across the selected video frames. Initial observations of both male and female groups suggested some variations in huddling behavior among male and female groups; however, these results should be interpreted cautiously due to a small sample. Group behavior is known to be disrupted in several neuropsychiatric disorders, such as autism. Various mouse models of these disorders have been proposed. Our measurement system, when combined with drug or genetic modification screening, could provide a valuable tool for high-throughput analyses of huddling behavior.