Meh, better we use these models than entire living mice or rats, which would be the alternative. I highly doubt there is any kind of sensation or consciousness inside of the brain models, seeing as how they have no sensory inputs or organic energy inputs (especially oxygen) whatsoever. On top of that, even 5 week old fetuses (which these model brains are definitively not) aren't remotely viable or sensate anyway, and don't even have an associated behavior model AFAIK.
The ethical boundaries for experimenting on living mice are, in my opinion, a bit perverse at the extremes. There's a general consensus that mice are sensate and can experience in some form basic emotions and learning behaviors. Despite this, it's acceptable to do experiments which deplete or wildly manipulate various neurotransmitters or neural circuits inside of the mouse's brain far beyond normal physiology.
Imagine having 100% of the "feel good" chemicals removed from your brain and replaced with 10,000% the normal concentration of "feel bad" chemicals. Obviously this is a huge simplification, but it's pretty clear that it would be hellish-- and that experiment has actually been done using mice. Sure, it's not as bad as if it were done with a real person, but it'd be much better if we could spare the mice and use a model brain in a vat instead.
I gave an answer on Reddit a week or two ago to a what might be considered the current limiting case in clinical practice. In another comment in the same thread I tried to point out that there are a lot of edge cases, even where it seems to be a bright line.
It seems reasonable to me that we should monitor this train of research closely, and I'm pretty confident people will.
The ethical boundaries for experimenting on living mice are, in my opinion, a bit perverse at the extremes. There's a general consensus that mice are sensate and can experience in some form basic emotions and learning behaviors. Despite this, it's acceptable to do experiments which deplete or wildly manipulate various neurotransmitters or neural circuits inside of the mouse's brain far beyond normal physiology.
Imagine having 100% of the "feel good" chemicals removed from your brain and replaced with 10,000% the normal concentration of "feel bad" chemicals. Obviously this is a huge simplification, but it's pretty clear that it would be hellish-- and that experiment has actually been done using mice. Sure, it's not as bad as if it were done with a real person, but it'd be much better if we could spare the mice and use a model brain in a vat instead.