A Real-Time Interactive System for Studying Confrontational Pursuit Behavior in Rodents

Summary

Here, we present a protocol to detect and quantify predatory pursuit behavior in a mouse model. This platform provides a new research paradigm for studying the dynamics and neural mechanisms of predatory pursuit behavior in mice and will provide a standardized platform for studying pursuit behavior.

Abstract

Predatory pursuit behavior involves a series of important physiological processes, such as locomotion, learning, and decision-making that are critical to the success of an animal in capturing prey. However, there are few methods and systems for studying predatory pursuit behavior in the laboratory, especially in mice, a commonly used mammalian model. The main factors limiting this research are the uncontrollability of live prey (e.g., crickets) and the challenge of harmonizing experimental standards. The goal of this study was to develop an interactive platform to detect and quantify predatory pursuit behaviors in mice on a robotic bait. The platform uses computer vision to monitor the relative positions of the mouse and robotic bait in real time to program the motion patterns of the robotic bait, and the interactive two-dimensional sliders magnetically control the movement of the robotic bait to achieve a closed-loop system. The robotic bait is able to evade approaching hungry mice in real-time, and its escape speed and direction can be adjusted to mimic the predatory pursuit process in different contexts. After a short period of unsupervised training (less than two weeks), the mice were able to perform the predation task with a relatively high efficiency (less than 15 s). By recording kinematic parameters such as speed and trajectories of the robotic bait and the mice, we were able to quantify the pursuit process under different conditions. In conclusion, this method provides a new paradigm for the study of predatory behavior and can be used to further investigate the dynamics and neural mechanisms of predatory pursuit behavior.

Introduction

The pursuit of prey by predators is not only a vivid demonstration of the struggle for survival but also a key driver of species evolution, maintaining the ecological balance and energy flow in nature^1,2. For predators, the activity of pursuing prey is a sophisticated endeavor that involves a variety of physiological processes. These processes include the motivational states that drive the predator to hunt³, the perceptual abilities that allow it to detect and track prey^4,5,6, the decision-maki....

Protocol

Adult C57BL/6J mice (male, 6-8 weeks old) are provided by the Army Medical University Laboratory Animal Center. All experimental procedures are performed in accordance with institutional animal welfare guidelines and are approved by the Animal Care and Use Committee of the Army Medical University (No. AMUWEC20210251). Mice are housed under temperature-controlled conditions (22-25°C) with a 12-h reverse light/dark cycle (lights on 20:00-8:00) and free access to food and water.

1. Hardware preparation for real-time interactive platform

1. Mount a webcam on a crossbar above the entire platform to monitor the posi....

Results

To escape from a predator, prey often employs flexible and variable escape strategies, such as changing escape speeds or fleeing in unpredictable directions^21,22,23. In this study, the movement pattern of the robotic bait is flexibly controlled in speed and direction so that we can change the escape direction as well as the speed of the robotic bait to simulate the predation task under different conditions, respectively.

Discussion

In this protocol, to achieve real-time control with low system latency, we use OpnenCV, a lightweight and efficient computer vision library, and a color model to identify the positions of the mice and the robot decoy. This requires that the lighting in the arena is relatively stable and that the shadows in the arena are avoided as much as possible to avoid interfering with the detection of the black mice. To obtain relatively stable contour detection, we capture the color ranges of the mice with the robotic decoys at sev.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Acrylic cylinder	SENTAI	PMMA	Diameter 800 mm Height 300 mm Thickness 8 mm
Anti-vibration table	VEOO	Custom made	Length 1500 mm Width 1500 mm Height 750 mm
Camera	JIERUIWEITONG	HF868SS	Pixel Size 3 µm ´ 3 µm 480P: 120 fps
Camera support frame	RUITU	Custom made	Maximum width 3300 mm Maximum height 2600 mm
Circuit board	WXRKDZ	Custom made	Length 60 mm Width 40 mm Hole spacing 2.54 mm
Computer	DELL	Precision 5820 Tower	Inter(R) Xeon(R) W-2155 CPU NVIDIA GeForce RTX 2080Ti
DuPont Line	TELESKY	Custom made	30 cm
Food pellets	Bio-serve	F07595	20 mg
Platform support frame	HENGDONG	OB3030	Length 1600 mm Height 900 mm Width 800 mm
Regulated power supply	ZHAOXIN	PS-3005D	Output voltage: 0-30 V Output current:0-3 A
Round magnetic block	YPE	YPE-230213-5	Diameter 40 mm Thickness 10 mm
Servo Motor Driver	FEREME	FCS860P	0.1 kw-5.5 kw SVPWM 220 VAC+10% ~-15% RS-485
Slide rail	JUXIANG	JX45	Length 1000 mm Width 1000 mm
Square acrylic plate	SENTAI	PMMA	Length 800 mm Width 800 mm Thickness 10 mm
Square Magnetic Block	RUITONG	N35	Length 100 mm Width 50 mm Thickness 20 mm
Stm32	ZHENGDIANYUANZI	F103	STM32F103ZET6 72 MHz clock
Transistor	Semtech	C118536	2N2222A, NPN