Neuroprosthetics research has entered a stage in which animal models and proof-of-concept studies are translated into clinical applications, often combining implants with artificial intelligence techniques. This new phase raises the question of how clinical trials should be designed to scientifically and ethically address the unique features of neural prostheses. Neural prostheses are complex cyberbiological devices able to acquire and process data; hence, their assessment is not reducible to only third-party safety and efficacy evaluations as in pharmacological research. In addition, assessment of neural prostheses requires a causal understanding of their mechanisms, and scrutiny of their information security and legal liability standards. Some neural prostheses affect not only human behaviour, but also psychological faculties such as consciousness, cognition, and affective states. In this Viewpoint, we argue that the technological novelty of neural prostheses could generate challenges for technology assessment, clinical validation, and research ethics oversight. To this end, we identify a set of methodological and research ethics challenges specific to this medical technology innovation. We provide insights into relevant ethical guidelines and assess whether oversight mechanisms are well equipped to ensure adequate clinical and ethical use. Finally, we outline patient-centred research ethics requirements for clinical trials involving implantable neural prostheses.
In a recent clinical trial involving groundbreaking neuroprosthetic technology,1 a paralysed individual received a brain implant that allowed him to access the internet and communicate directly with external technologies and environment (digital communication) through the implant (eg, typing and wheelchair and cursor control, etc), eliminating the need for the slow method of using a mouth stick. This implant improved his life substantially, enabling him to switch between websites and audiobooks easily, and even engage in conversations while playing chess. However, about a month after implantation, he noticed a decline in cursor control precision and delays between his thoughts and computer actions. This might have resulted from the electrodes losing their connection, disrupting the connection quality between his brain and the computer. This issue was partially counteracted by re-setting and improving the decoding algorithms. This case highlights the potential challenges in advancing neural prostheses technology.
Implantable neural prostheses encompass a spectrum of implantable systems that establish a functional connection between the human nervous system—either peripheral or central—and robotic or other digital technology.2 Peripheral neural prostheses interact with the peripheral nervous system to control prosthetic limbs, diminish pain, or restore sensation by translating neural signals from residual muscles or nerves into electromechanical actions (nerve–machine interface).3–9 Brain–machine interfaces connect with brain tissue directly, enabling the brain to interact bidirectionally with computers or other electronic devices.10–15 Some neural prostheses focus primarily on translating neural signals into digital commands (eg, for the control of prosthetic devices), and others enable stimulation capabilities. These neural prostheses include clinically established neurostimulation systems, such as implants for spinal neuromodulation,16 which have already been widely adopted for the treatment of chronic pain, and novel paradigms. Newer such stimulation devices to treat or restore sensorimotor functions include upper and lower limb neuroprostheses;3–9 spinal cord-stimulating systems for walking, grasping, or blood pressure restoration after stroke or spinal cord injury;17–20 or brain stimulation.21
Neural prostheses research is now entering a new phase in which animal models and proof-of-concept studies are increasingly being translated into clinical trials and, ultimately, into novel clinical applications, propelled by large international research collaborations and industrial interest. Clinical trials are ongoing to translate technological breakthroughs in human–machine systems22 into the language of the nervous system and deliver electrical stimulation to the residual nerves,3–9 spinal cord,17–20 or brain10,12–15 of individuals with neurological disabilities (figure 1). Companies such as Neuralink24 and Blackrock Neurotech25 are developing multiwire brain implants, and various neural prostheses are being produced by Inbrain Neuroelectronics,26 Synchron,27 Precision Neuroscience, Paradromincs, and CorTec Neuro. ONWARD Medical17 is testing spinal interfacing for spinal cord rehabilitation after injury, and Iota BioScience,28 Neuros Medical,29 Neuronoff,30 Galvani Bioelectronics31 are implanting peripheral nervous system electrode devices into the somatosensory and autonomic nervous system to gain certifications for pain treatment, among other companies.