Ethical challenges of neurotechnologies require humanistic studies. Photo: TUCHONG

The rapid advance of science and technology, particularly breakthroughs in neuroscience and cognitive science, has enabled us to probe the mysteries of the brain with unprecedented depth and scope. This progress has propelled the swift development of disciplines such as medicine and psychology, while also sparking renewed debates over questions of human nature and the origins of consciousness. At the same time, it has raised a host of ethical and moral challenges.

Neurotechnologies & ethical challenges

More than half a century ago, the invention of X-ray computed tomography (X-CT) revolutionized medical diagnosis. The subsequent emergence of positron emission tomography (PET), magnetic resonance imaging (MRI), and functional magnetic resonance imaging (fMRI) provided powerful tools for exploring the neural basis of human behavior. These innovations fundamentally transformed research in psychology, neuroscience, and related fields, giving rise to a new discipline—cognitive neuroscience. Initially, such technologies were used only in studies of cognition, including language, memory, and visual perception. By the mid-1990s, they began to be applied to the study of emotion, paving the way for the rise of social neuroscience, in which emotion and cognition in interpersonal communication became central subjects of inquiry.

During this period, methods of functional neuroimaging analysis also advanced, including solutions to false positive activations in whole-brain analyses and approaches to studying functional connectivity. Structual methods such as voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) also emerged. Yet what poses the most profound challenge is not the techniques themselves, but the ethical and social implications of the brain imaging data they generate. The most direct ethical concern is the invasion of brain privacy. In reality, the information gleaned from brain imaging remains quite limited. Martha J. Farah of the University of Pennsylvania and her colleagues found that the personal psychological characteristics collected through brain imaging are extremely limited, and the predictive power so low as to be of little practical value. Public misunderstandings of neuroimaging, however, risk encouraging premature commercialization, which could in turn harm consumers.

Meanwhile, the ongoing development of artificial intelligence not only makes it possible to automatically process and analyze massive volumes of neuroimaging data, but also, through deep learning, to extract subtle traces of individual traits, emotions, and concepts from brain signals. This capacity is likely to provoke a new wave of ethical debate.

In recent years, as understanding of brain mechanisms has deepened and technology has advanced, neuromodulation techniques have emerged. These methods aim to regulate and optimize brain function by applying targeted electrical, mechanical, magnetic, or thermal stimulation to the nervous system, thereby altering neuronal firing patterns and inter-neuronal connections. Neuromodulation not only provides new experimental approaches for neuroscience but also opens up possibilities for treating neurological disorders, enhancing cognitive performance, and even regulating emotions. Yet it has also triggered wide-ranging discussions about ethics, safety, and privacy.

Non-invasive neuromodulation methods raise several ethical concerns. Media coverage of these technologies and devices strongly shapes public perception. Because they directly affect brain activity, they are more likely to cause unintended side effects. They can not only help repair damage caused by illness but also enhance cognitive abilities, leading to unease about their possible impact on personal identity or sense of self.

Invasive techniques, represented by deep brain stimulation (DBS), present additional challenges. Unlike non-invasive methods, they intervene in the body in a more direct and enduring way. They accompany patients throughout treatment and, in a sense, gradually integrate into the body as part of it. This raises a new set of ethical questions. Given the unique nature of invasive neuromodulation and the complexity of the issues involved, it is useful to consider them alongside another frontier technology—brain-computer interfaces (BCIs). Like DBS, BCIs establish direct information exchange with the brain, blurring the boundary between organism and machine and ushering in a new era of integration between neuroscience and information technology.

The rapid development of closed-loop brain devices offers hope for treating neurological disorders, but it also intensifies ethical and social implications. These include the impact on a person’s sense of agency, potential alterations to identity and personality, privacy risks, problems of responsibility and accountability, and particularly pressing questions of informed consent in the context of DBS and BCI applications.

Brain organoids & consciousness

Whether invasive or non-invasive, brain science technologies still face limitations in exploring early brain development and the mechanisms of brain disease. The advent of brain organoids has begun to change this. Brain organoids are self-organizing cell structures derived from human pluripotent stem cells (such as embryonic or induced pluripotent stem cells) that replicate, in three dimensions, the whole brain or specific brain regions. They may be formed entirely of biological material or of biological samples combined with synthetic biomaterials. Beyond in vitro culture, human brain organoids can also be transplanted into animal models for further growth and differentiation.

This breakthrough has opened new avenues for studying human neural development and brain disease. Brain organoids have played a key role, for instance, in clarifying the pathogenic mechanisms of the Zika virus. They also have potential applications in creating personalized disease mechanism models, therapeutic screening, and repairing damaged neural circuits. Yet despite their promise, brain organoids have also sparked widespread ethical debate and public concern.

First, brain organoid research typically does not target individual patients, which might suggest that informed consent is not necessary. In reality, however, the work depends on biological materials—pre-implantation embryos, gametes, and somatic cells—that are essential for producing organoid stem cell lines. Because people closely associate self-awareness with the brain, some donors may be unwilling to see their stem cells used to cultivate brain organoids, especially when these are transplanted into animal models. Researchers working with pluripotent stem cells or brain tissue therefore need to provide donors with clear and detailed explanations of their research plans.

Second, given the current state of technology, consciousness-related moral concerns appear unlikely to arise. As Insoo Hyun, director of the Center for Life Sciences and Public Learning at the Museum of Science, and his colleagues note, if “consciousness” is taken to mean the most basic neuronal activity of the cortex under stimulation, then virtually no ethical issues are involved. More complex states of consciousness—such as awareness of sensory input, wakefulness, alertness, focused attention, perception, or subjective self-awareness—require long-range integration across many cortical regions, which current brain organoids lack. They do not yet possess the full range of cell types, complex network structures, or sensory inputs needed to produce recognizable subjective experiences. Moreover, even a natural human newborn brain requires sufficient social interaction to develop human cognition. Under present experimental conditions, the assumption that brain organoids might generate consciousness does not amount to a substantive ethical challenge.

Still, concerns over consciousness is not entirely unfounded. Nita A. Farahany, a professor of law and philosophy at Duke University and others have raised a series of thought-provoking questions regarding standards of measurement, the definition of death, ownership, post-experiment disposal of brain organoids, and the boundaries of animal research.

Ethical & legal frameworks

As brain organoid technologies continue to develop, it is essential not only to focus on their vast potential in scientific research and medical applications but also to anticipate risks and establish comprehensive ethical frameworks and legal norms. These are needed to ensure healthy technological progress while respecting and protecting all forms of life that may be affected.

As Farah has argued, neuroscience provides not only new tools but also a new lens for viewing human nature: It allows us to interpret human behavior in terms of physical mechanisms. While we readily analyze the “behavioral” mechanisms of objects and systems through physical causality, when it comes to humans we are inclined to seek subjective intention. Yet neuroscience increasingly shows that human behavior can also be explained by causal physical processes.

This raises a profound question: How does such an assumption reshape our understanding of moral and legal responsibility? We do not normally blame people for reflexive behaviors (such as the knee-jerk reflex), actions taken in diminished states of awareness (such as sleepwalking or hypnosis), or behavior under coercion (such as when threatened at gunpoint), because we do not consider such acts to be the product of free will. The problem with a purely neuroscientific account is that it risks reducing all behavior to a kind of “knee-jerk” response—a sequence of inevitable physical events. Current neuroscientific explanations are not strong enough to justify immoral behavior, and “Laplace’s demon” at the neural level remains unconvincing. Still, such accounts do influence the way people think and act.

We tend to value most objects according to their practical utility. Humans, however, possess what Kant called “dignity”—an intrinsic worth beyond instrumental value. If all aspects of human beings are reduced to physical mechanisms, the distinction between persons and things becomes blurred. If we are nothing more than complex entities built on powerful computational networks, then why should the fates of objects with human brains matter more than those of other natural or artificial objects?

In conclusion, neuroscience is both challenging and reshaping our traditional understanding of human nature. While this could tempt us toward a mechanistic determinism that views people as machines devoid of agency and intrinsic worth, it is more likely to inspire the construction of a more inclusive and humane society—one that recognizes human behavior as the outcome of complex causal interactions, and each individual as an indispensable part of a larger whole, bearing unique moral significance and value.

Liu Chao (professor) and Sun Wenzhao are from the State Key Laboratory of Cognitive Neuroscience and Learning at Beijing Normal University.