Yes, if you assume the technical model of each neuron only having one scalar output bfloat16, then we could simulate insect brains right now. But the technical neuron model of sum of inputs plus sigmoid activation function is only an approximation.
Neurons communicate with each other with a multitude of neurotransmitters and receptors [1]. As a cell, each neuron is a complex organism of its own that undergoes transcriptomic and metabolic changes. We aren't even close to simulating all protein interactions in a single cell yet, let alone in millions of them.
Of course you could say that full protein simulation of an entire brain is not neccessary if we can build an accurate enough technical model of a single neuron. In fact, already now we have to apply a model of how we believe proteins behave as "properly" simulating interactions of two proteins (or one with itself) with lattice QCD approaches is beyond our computational capabilities. For protein interaction we have pretty good models already. But finding a model of all types of neurons in insect brains is right now an open, unsolved challenge.
AFAICT this suggests that we have the computational power but wouldn't it also be a significant challenge to create an accurate model for the brain simulation?
Yes, that's my point: you don't need to simulate a protein with that tool because we have good enough models of higher level structures like atoms. And similarly we might find models for neurons that allow us to avoid full emulation all protein interactions. We figured out how atoms work before we figured out how nuclei work, but with neurons it's the opposite: we know/can figure out how the the parts (proteins) of the machine work but not how the entire machine works.
Neurons communicate with each other with a multitude of neurotransmitters and receptors [1]. As a cell, each neuron is a complex organism of its own that undergoes transcriptomic and metabolic changes. We aren't even close to simulating all protein interactions in a single cell yet, let alone in millions of them.
Of course you could say that full protein simulation of an entire brain is not neccessary if we can build an accurate enough technical model of a single neuron. In fact, already now we have to apply a model of how we believe proteins behave as "properly" simulating interactions of two proteins (or one with itself) with lattice QCD approaches is beyond our computational capabilities. For protein interaction we have pretty good models already. But finding a model of all types of neurons in insect brains is right now an open, unsolved challenge.
[1] https://en.wikipedia.org/wiki/Neurotransmitter#List_of_neuro...