Organoids are three-dimensional biological structures grown in vitro from different kinds of stem cells that self-organise mimicking real organs with organ-specific cell types. Recently, researchers have managed to produce human organoids which have structural and functional properties very similar to those of different organs, such as the retina, the intestines, the kidneys, the pancreas, the liver and the inner ear. Organoids are considered a great resource for biomedical research, as they allow for a detailed study of the development and pathologies (...) of human cells; they also make it possible to test new molecules on human tissue. Furthermore, organoids have helped research take a step forward in the field of personalised medicine and transplants. However, some ethical issues have arisen concerning the origin of the cells that are used to produce organoids and their properties. In particular, there are new, relevant and so-far overlooked ethical questions concerning cerebral organoids. Scientists have created so-called mini-brains as developed as a few-months-old fetus, albeit smaller and with many structural and functional differences. However, cerebral organoids exhibit neural connections and electrical activity, raising the question whether they are or will one day be somewhat sentient. In principle, this can be measured with some techniques that are already available, which are used for brain-injured non-communicating patients. If brain organoids were to show a glimpse of sensibility, an ethical discussion on their use in clinical research and practice would be necessary. (shrink)

This book explores how we can measure consciousness. It clarifies what consciousness is, how it can be generated from a physical system, and how it can be measured. It also shows how conscious states can be expressed mathematically and how precise predictions can be made using data from neurophysiological studies.

In his interesting commentary, Joshua Shepherd raises two points—one related to epistemology, the other to ethics—about our article on human cerebral organoids.1 2 From the epistemological standpoint, he calls into question the need for a theory of consciousness. A theory of consciousness, for him, is not necessary because of the lack of consensus about the very nature of consciousness. Shepherd suggests that ‘given widespread disagreement, applying a theory of consciousness may not be helpful when attempting to diagnose the presence of (...) consciousness in cerebral organoids’. In Shepherd’s view, it would be better to transfer ‘concepts already under development in work on the presence and structure of consciousness in difficult marginal cases involving traumatic brain injury’.2 We could not agree more on this last point; detecting a minimal capacity for consciousness in the brain of comatose patients is a very similar challenge to inferring the presence of consciousness in cerebral organoids. Every day, as a by-product of saving many lives, intensive care medicine artificially produces thousands of brains that may remain isolated, split or fragmented; in the worst case, cortical islands, or an archipelago of islands, may survive while being disconnected from the outside world. Can these islands host some form of consciousness? That is, does it feel like anything to be a large piece of human cortex? Addressing this difficult question requires the development of general, objective brain-based indices of consciousness that are independent of sensory processing, executive functions and motor outputs.3 Consider, for example, a patient showing reflexive spontaneous behaviour, no response to command and no ability to communicate. In her brain, afferent pathways are damaged, thereby impairing the recruitment of cortical areas in response to sensory stimulation; basal ganglia, as well as other frontal structures supporting executive functions, are impaired. However, resting metabolism and significant electroencephalography …. (shrink)

Which systems/organisms are conscious? New tests for consciousness (‘C-tests’) are urgently needed. There is persisting uncertainty about when consciousness arises in human development, when it is lost due to neurological disorders and brain injury, and how it is distributed in nonhuman species. This need is amplified by recent and rapid developments in artificial intelligence (AI), neural organoids, and xenobot technology. Although a number of C-tests have been proposed in recent years, most are of limited use, and currently we have no (...) C-tests for many of the populations for which they are most critical. Here, we identify challenges facing any attempt to develop C-tests, propose a multidimensional classification of such tests, and identify strategies that might be used to validate them. (shrink)

Interpreting empirical measures of integration and differentiation as indices of cortical performance and memory consolidation during wakefulness rather than consciousness per se is inconsistent with the literature. Recent studies show that these theory-inspired measures can dissociate from such processes and reliably index the brain's capacity for experience. We consider this as a positive trend in consciousness research.

: If we were asked to draw a graph to represent the distribution of consciousness in the world around us based on objective criteria, we would definitely be in trouble. The two objective parameters that have been traditionally considered as a guide – the complexity of behavior and brain size – lead to paradoxical conclusions and turn out to be unsatisfactory, to say the least. We need to find novel, reliable metrics. However, these can be identified, validated and calibrated only (...) if we first tackle seriously the problem of recognizing consciousness in our fellow humans, a task which is far from being obvious. Keywords: Consciousness; Animal; Brain; Behaviour; Coma La distribuzione della coscienza: un difficile diagramma cartesiano Riassunto: Se ci chiedessero di tracciare un grafico per rappresentare la distribuzione della coscienza nel mondo che ci circonda su una base oggettiva, ci troveremmo sicuramente in difficoltà. I due criteri oggettivi che sono stati tradizionalmente presi in considerazione come guida – la complessità del comportamento e la dimensione del cervello – conducono a conclusioni paradossali rivelandosi, come minimo, insoddisfacenti. È necessario individuare altre misure. Ma queste potranno essere individuate, validate e calibrate soltanto se prima affronteremo seriamente il problema di riconoscere la coscienza nell’uomo, un compito tutt’altro che scontato. Parole chiave: Coscienza; Animale; Cervello; Comportamento; Coma. (shrink)