Given the revolutionary role of metaverses, healthcare metaverses are emerging as a transformative force, creating intelligent healthcare systems that offer immersive and personalized services. The healthcare metaverses allow for effective decision-making and data analytics for users. However, there still exist critical challenges in building healthcare metaverses, such as the risk of sensitive data leakage and issues with sensing data security and freshness, as well as concerns around incentivizing data sharing. In this paper, we first design a user-centric privacy-preserving framework based on decentralized Federated Learning (FL) for healthcare metaverses. To further improve the privacy protection of healthcare metaverses, a cross-chain empowered FL framework is utilized to enhance sensing data security. This framework utilizes a hierarchical cross-chain architecture with a main chain and multiple subchains to perform decentralized, privacy-preserving, and secure data training in both virtual and physical spaces. Moreover, we utilize Age of Information (AoI) as an effective data-freshness metric and propose an AoI-based contract theory model under Prospect Theory (PT) to motivate sensing data sharing in a user-centric manner. This model exploits PT to better capture the subjective utility of the service provider. Finally, our numerical results demonstrate the effectiveness of the proposed schemes for healthcare metaverses.

Recent technological advancements have considerately improved healthcare systems to provide various intelligent healthcare services and improve the quality of life. Federated learning (FL), a new branch of artificial intelligence (AI), opens opportunities to deal with privacy issues in healthcare systems and exploit data and computing resources available at distributed devices. Additionally, the Metaverse, through integrating emerging technologies, such as AI, cloud edge computing, Internet of Things (IoT), blockchain, and semantic communications, has transformed many vertical domains in general and the healthcare sector in particular. Obviously, FL shows many benefits and provides new opportunities for conventional and Metaverse healthcare, motivating us to provide a survey on the usage of FL for Metaverse healthcare systems. First, we present preliminaries to IoT-based healthcare systems, FL in conventional healthcare, and Metaverse healthcare. The benefits of FL in Metaverse healthcare are then discussed, from improved privacy and scalability, better interoperability, better data management, and extra security to automation and low-latency healthcare services. Subsequently, we discuss several applications pertaining to FL-enabled Metaverse healthcare, including medical diagnosis, patient monitoring, medical education, infectious disease, and drug discovery. Finally, we highlight significant challenges and potential solutions toward the realization of FL in Metaverse healthcare.

XRHealth, the gateway to the healthcare metaverse, announces that the company adds NeuroReality's cognitive training to their virtual clinics. The NeuroReality's virtual reality neurorehab, a serious game, is an immersive experience known as Koji's Quest. It was designed for individuals who suffer from the consequences of stroke and brain injuries, where patients are guided through activities aimed to help regain functionality in their everyday lives. "We are constantly adding state-of-the-art virtual reality therapeutic programs for our users so they can have a one-stop-shop for all their rehabilitation needs," says Eran Orr, Founder & CEO of XRHealth. "We find that patients enjoy the game-like therapy experiences and are more likely to stick with the prescribed programs since they are engaging from the comfort of their home."

Facebook announced last year that it was committed to putting $10 billion into the virtual world: its metaverse division. And last week, news broke that Microsoft was nearing a $70 billion deal to buy Activision Blizzard, the video game publisher of World of Warcraft and other top-selling games. As Microsoft's biggest entry into gaming, the deal indicates the company is betting big on the growth of the virtual space, as it works to compete with tech rivals like Facebook. It's clear that the metaverse -- a new virtual reality sector that reimagines the internet as a 3D experience that users can be a part of -- is being hyped by tech titans as the future of the internet, but what does it mean for the future of healthcare? The COVID-19 pandemic ushered in a new healthcare consumer conditioned to home delivery of medicines and receiving healthcare online through telehealth visits (including Medicare recipients).