Thanks very much indeed!

There is a level where the criticisms of the neuroscientists are both entirely legitimate and at the same time probably not really valid.

Again, to go to an SF reference, the Australian hard-SF writer and mathematician Greg Egan has gone into this at some depth. I can't call which story to mind now, but he imagined a scenario in one of his where the tech is available to do a full whole-body in-silico emulation of a human: every dendrite of every brain cell, every action potential propagating along it, every neurotransmitter diffusing across every synapse.

And what the people running the simulations AND THE PEOPLE BEING SIMULATED discover is that you don't need it most of the time.

In the story, doing the neocortex of the brain and a coarser sim of the underlying structures is enough to support full consciousness. For the peripheral nervous system, an even lower-level sim is enough: your limbs still feel right. For the sympathetic nervous system, you don't bother at all -- just simulate overall excitation levels.

Don't bother doing whole muscles, as most people aren't consciously aware of them anyway, even when running or doing sport -- any more than we're aware of breathing.

You downgrade the sim of everything except the important bits to a coarse low-res approximation and most of the time you wouldn't be able to tell -- but it's much faster and takes much less CPU time, so the same compute substrate can simulate more people faster for a given amount of resources.

No, this is not a full simulation of all the nerve cells in a fly brain, but it seems like it does more or less what a fly would do anyway. It seems quite possible that for a fly, a coarse low-level generalised simulation might be enough to produce something that walks like a fly, feeds like a fly, and maybe flies like a fly and breeds like a fly.

I don't think a fly "knows" which leg to move when walking. I suspect a horse doesn't. I barely do, and I only have 2 of them.

Crude abstracted low-level sims with the right structure might be enough to get the desired behaviour and have a model that's good enough that its behaviour is indistinguishable from the original.

In human terms... if we ever get to the point that we can simulate a brain in a jar, if the sim "lies" to the brain and tells it a body is there, and is doing the normal body stuff and walking and swinging its arms and whatever, that might be enough to "feel real" to the mind in the simulated body.

Do it for an athlete or sports player or a gymnast or a bodybuilder and they'd notice. They'd know. But most of us never would.

You can't feel your individual toes unless you stub one. So don't simulate them.

A low-res fly brain model connected to a lower-res overall ventral nerve cord connected to a trivial fly muscle body which doesn't even simulate individual muscles might be enough that the fly does everything a fly can do.

How the Eon Team Produced a Virtual Embodied Fly