Growing brain tissue in a vat is relatively hard and expensive compared to growing brain tissue in an animal. Also, it’s going to be less well-ordered neural nets, which matters a lot. Well organized cortical microcolumns work well, disordered brain tissue works much less well.
Yep, I agree. I vaguely alluded to this by saying “The main additional obstacle [...] is growing cognitively useful tissue in vitro.”; what I have in mind is stuff like:
Well-organized connectivity, as you say.
Actually emulating 5-minute and 5-day behavior of neurons—which I would guess relies on being pretty neuron-like, including at the epigenetic level. IIUC current in vitro neural organoids are kind of shitty—epigenetically speaking they’re definitely more like neurons than like hepatocytes, but they’re not very close to being neurons.
Appropriate distribution of cell types (related to well-organized connectivity). This adds a whole additional wrinkle. Not only do you have to produce a variety of epigenetic states, but also you have to have them be assorted correctly (different regions, layers, connections, densities...). E.g. the right amount of glial cells...
Yep, I agree. I vaguely alluded to this by saying “The main additional obstacle [...] is growing cognitively useful tissue in vitro.”; what I have in mind is stuff like:
Well-organized connectivity, as you say.
Actually emulating 5-minute and 5-day behavior of neurons—which I would guess relies on being pretty neuron-like, including at the epigenetic level. IIUC current in vitro neural organoids are kind of shitty—epigenetically speaking they’re definitely more like neurons than like hepatocytes, but they’re not very close to being neurons.
Appropriate distribution of cell types (related to well-organized connectivity). This adds a whole additional wrinkle. Not only do you have to produce a variety of epigenetic states, but also you have to have them be assorted correctly (different regions, layers, connections, densities...). E.g. the right amount of glial cells...