Abstract
Human cerebral organoids are three-dimensional biological cultures grown in the laboratory to mimic as closely as possible the cellular composition, structure, and function of the corresponding organ, the brain. For now, cerebral organoids lack blood vessels and other characteristics of the human brain, but are also capable of having coordinated electrical activity. They have been usefully employed for the study of several diseases and the development of the nervous system in unprecedented ways. Research on human cerebral organoids is proceeding at a very fast pace and their complexity is bound to improve. This raises the question of whether cerebral organoids will also be able to develop the unique feature of the human brain, consciousness. If this is the case, some ethical issues would arise. In this article, we discuss the necessary neural correlates and constraints for the emergence of consciousness according to some of the most debated neuroscientific theories. Based on this, we consider what the moral status of a potentially conscious brain organoid might be, in light of ethical and ontological arguments. We conclude by proposing a precautionary principle and some leads for further investigation. In particular, we consider the outcomes of some very recent experiments as entities of a potential new kind.
Notes
1 It should be noted that, in its evolutionary function, pain may be also conceived as simply nociception, which is different than suffering.
2 Thanks to an anonymous reviewer for pressing us on the point of independent verification.
3 A very recent paper presented an MRI reference chart that can show morphological changes in the brain from the foetal state (115 days post-conception) to 100 years of age (Bethlehem et al. Citation2022). It can be assumed that this morphological analysis may also be useful for future comparisons of the physiological neuronal structures of HCOs, for example, with the brains in the foetal state.
4 We thank an anonymous reviewer for suggesting this addition to the text.
5 However, the level of moral status to be attributed to these patients with disorders of consciousness is much debated (Zilio Citation2020).
6 Not the only characteristic and not a necessary one; in fact, it could be considered as a sufficient non-necessary condition.
7 The ISSCR guidelines criticise public communication of research on HCOs that makes unfounded overstatements cognitive abilities, consciousness, or self-awareness in brain organoids (International Society For Stem Cell Research Citation2021, 52). Nevertheless, at the same time, they recommend that researchers “should be aware of any ethical issues that may arise in the future as organoid models become more complex through long-term maturation or through the assembly of multiple organoids” (10).
8 It should be noted that the authors use sentience in a slightly different sense from the one referred to in this paper: “sentience as being ‘responsive to sensory impressions’ through adaptive internal processes”; Kagan et al. Citation2022, 3952).