## 4 Discussion
### Limitations and Directions of Further Studies  
While the integration of brain-computer interfaces and virtual reality holds great promise, there are still several challenges and limitations that need to be addressed. One key challenge is the accuracy and reliability of BCI systems in decoding and interpreting brain signals, which can be influenced by factors such as individual variations, mental states, and environmental conditions. Continued research and advancements in signal processing, machine learning, and neural decoding algorithms are necessary to improve the robustness and effectiveness of BCI-VR systems. Another limitation is the potential for motion sickness and disorientation that can arise from prolonged immersion in virtual environments. To address this, researchers will need to explore innovative approaches that integrate additional sensory modalities, such as vestibular and proprioceptive cues, into the VR experience. Strategies like incorporating multimodal feedback, including haptic, auditory, and visual cues, can help create a more coherent and intuitive sensory experience, mitigating the risk of motion sickness and disorientation [69]. The high cost of high-quality BCI and VR equipment can be a significant barrier to accessibility, limiting their adoption by consumers and researchers. This financial constraint can prevent individuals, healthcare providers, and research institutions from accessing these cutting-edge technologies, thereby restricting the widespread implementation and potential benefits of BCI-VR systems. The lack of standardized protocols and interfaces for BCI-VR integration hinders the development of interoperable solutions, which are crucial for enabling seamless integration and widespread adoption of these technologies. The absence of such standards and compatibility can hamper the ability to create and deploy scalable, cross-platform BCI-VR applications, further limiting their accessibility and impact. The integration of BCI technology into virtual environments and personal devices also raises important ethical concerns that need to be carefully addressed, such as issues of privacy, data security, and potential risks associated with BCI technology, like unintended cognitive or neural impacts. Ensuring the responsible and ethical development and deployment of these systems is essential to protect the well-being of BCI users and maintain public trust in these transformative technologies. Leveraging emerging technologies, such as augmented reality and wearable sensors, can further enhance the user experience and expand the applications of BCI-VR systems [70; 71; 72]. Future research should also focus on expanding the versatility and accessibility of BCI-VR systems. Adopting standardized protocols, improving user-friendlyinterfaces, and exploring cost-effective hardware solutions can broaden the reach and applicability of these integrated technologies [73, 74, 75, 76, 77, 78, 79, 80]. VR-BCI systems face technical limitations that challenge their accuracy and reliability. EEG signals, commonly used in BCI, are highly susceptible to noise from muscle movements, environmental interference, and other external factors that can compromise the accuracy of brain signal interpretation. The VR environments themselves often lack the full sensory and perceptual fidelity of real-world experiences, making it difficult to simulate realistic interactions that feel natural to users. Latency is another issue, as both EEG data processing and VR rendering can introduce delays that disrupt the synchronous feedback required for smooth user interaction. The limited spatial resolution of EEG sensors also limits the granularity of brain activity that can be captured, making it difficult to distinguish between complex cognitive states or intentions. Prolonged use of VR and BCI can lead to user fatigue or discomfort, which further compromises the usability and overall performance of the system for long-term use.