In order to solve problems related to the authenticity, immersion, interaction, and flexibility of rodent virtual reality systems, an immersive virtual reality system based on visual programming was constructed in this study. The system had the ability to flexibly modulate rodent interactive 3D dynamic experimental environments. The system included a central control unit, virtual perception unit, virtual motion unit, virtual vision unit, and video recording unit. The results demonstrated that the system could provide a new method and tool for analyzing the neural circuits of the higher cognitive functions in rodents.
Recently, Virtual Reality (VR) technology has been widely used in the field of neuroscience. VR systems could potentially be adopted to simulate virtual spaces, in which each component element of the virtual space could automatically be controlled. The experimental research conditions could then be strictly controlled, and scenes quickly switched many times during the experiments without artificial interference. Moreover, VR systems have rich scenario batteries which can effectively save physical space. In addition, more comprehensively realized and timely experimental data for analyses and research study can be acquired using VR systems.
Therefore, it is considered that VR systems have greatly enhanced both neuroscience and behavioristic research. VR has not only been adopted in research related to context cognition in rodents through virtual scenarios but also used to establish a series of rodent behavioral paradigms. In addition, the frontier issues in neuroscience may be further examined, such as decision making, spatial navigation, learning, and memory.
Higher cognitive functions involve multi-sensory integration and comprehensive cognition. The context includes various types of visual, auditory, tactile, and olfactory information within an entire external environment when events occur. Although, some laboratories throughout the world only construct virtual visual spaces, just as shown in Fig. 1. The full integration of virtual scenes with multi-sensory information remains challenging. Therefore, in order to provide a common platform for neuroscience and behavioristic studies, an immersive VR system was developed, which had the ability to record multi-sensory information with high flexibility for rodents. This system provided a new method and tool for analyzing the mechanisms of the neural circuits of higher cognitive functions.
The immersive virtual reality system proposed for the rodent′s study operated on a visual programming platform. The system consisted of the following eight modules: virtual auditory module, virtual olfactory module, virtual tactile module, virtual stimulus module, reward and punishment module, monitoring module, virtual motion device, and virtual vision device. These modules comprised an interactive, three-dimensional dynamic construction space for the experimental rodents, with the ability to record the multi-sensory information of the rodents. The system solved the problems related to the authenticity, immersion, and interactivities of the previously used VR systems. The virtual motion unit was designed based on a table tennis suspension device combined with a photoelectric positioning technique. For example, an environment was constructed using seven table tennis balls installed in a blower conditioning system, which was then used to suspend a foam ball. Then, head-fixed rodents were allowed to run freely in the environment. The running speeds and virtual positions of the rodents were recorded in real-time using an optical mouse device. The experimental rodents were able to interact with the environment efficiently and accurately.
The aforementioned system was oriented to the fields of neurobiology and behaviorism. It provided a high-flexibility experimental scheme that could be extended and optimized according to the different experimental requirements of the neurobiological researchers. The users who had limited program development foundations could also design, optimize, and develop the behavioral experiment by utilizing the control modules according to their requirements in the visual programming interface. Several custom blocks were used to convert all hardware and virtual environmental instructions into executed codes. This resulted in the experimenters with limited programming experience being able to easily set up and configure flexible experimental programs, as well as designing complex behavioral training schemes according to their requirements.
The remainder of this study is organized as follows. Section 2 illustrates the structure used in the proposed system and describes the design of every module and the associated software in detail. Section 3 presents the experimental results and the discussion of the results obtained. Finally, in Section 4, the conclusions are presented, and future work is outlined.
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An Immersive Virtual Reality System for Rodents in Behavioral and Neural Research
Li Liu, Zi-Yang Wang, Yu Liu, Chun Xu
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