> We all had a laugh when matrix mul exponent went from [2.3728]639 to [2.3728]596

Indeed. But the frustrating thing remains. Obviously animal and human brains do something similar, and obviously it's not even N^2, because anyone can count inputs and outputs for our brains, calculate N^2 and even at picowatts per operation that is just not happening ...

1000 Hz, ~800 input nerves, 20W power usage => 800 000 input values per second, squared, would leave 0.03 nW per input value. That's not enough to turn the handle on a single protein, so that's not happening. That's not enough to propagate the result of the calculation within a cell. A 2.3 power is out of the question.

One imagines maybe you can get to N^1.4 within that budget for whatever the brain is doing. Maybe. But that would be the limit.