Organoids, the small pieces of neural tissue grown from stem cells, dubbed “mini-brains”, and used in research, have been getting a lot of attention lately. Apparently a few neuroscientists are concerned that the organoids might be sentient, and suffering as experiments are performed on them. There’s growing concern that implanting human mini-brains in animal brains could lead to them becoming self aware. One guy is even worried that the mini-brains might eventually outsmart us and take over the world or something.
We don’t understand how consciousness is generated, the argument goes, so we can’t be completely sure these lumps of tissue aren’t conscious. However, the vast majority of neuroscientists aren’t particularly worried, and I think for good reasons. The probability that organoids are conscious is vanishingly small. And there are real people, who are unquestionably sentient and suffering, who could be helped by the research.
Still, people are worried, so I think it’s worth considering what the organoids don’t have. First, consider that, at least currently, they’re typically a few millimeters in diameter and have, at most, 1-2 million neurons in them, which puts them in cockroach territory in terms of nervous system size.
These neurons are not connected to any kind of sensory organs, so there’s no chance that sensory representations are being built. There are some with retinal cells that respond to light, but we’re talking about very primitive lower level functionality typically seen in the types of worms that very few people regard as conscious.
The neurons are grown in an artificial environment, without the typical support systems, such as glia, or the chemical signalling necessary to regulate gene expression, so the probability that they’ve wired any kind of survival circuitry, which is the source of the impulses that eventually become affective feelings, such as pain, hunger, fear, etc, is infinitessimal.
There’s just not enough there, and what’s there isn’t organized in the right way to process sensory information, have preferences about the states of affairs, or do any of the things we normally associate with consciousness, even if you hold to first order theories. If you hold to global workspace, higher order thought, or other similar types of theories, there definitely isn’t the necessary organization.
There is a growing concern as these organoids become larger and more developed, but I personally think even if an entire cortex was grown in isolation, it wouldn’t be conscious, at least not without the supporting subcortical infrastructure, such as a thalamus, amygdala, basal ganglia, hippocampus, midbrain, reticular formation, etc, nor would any of these structures, in isolation, be conscious. Although I’ll admit that the closer to an actual brain the grown structure gets, the less confident I’d feel about that conclusion.
Of course, there are theories of consciousness which might lead to people thinking these mini-brains have it. For instance, Christof Koch noted that the organoids would have a phi value, which under integrated information theory gives them some degree of consciousness. But whatever experience this might entail remains very hypothetical, and as noted above, has to be balanced against the definite sentience of suffering patients.
Overall, it seems to me, there are more pressing problems in the world to address than whether tiny clumps of neurons are suffering. But maybe I’m missing something?