You vastly overestimate how much we know about how our brains work.
Look up the neural correlates replication crisis, and e. g. the "dead salmon" study by Bennett et al.
That is we have unknowns that might increase or decrease estimates of computational demands of a functionally equivalent ANN. Not everything that happens in the brain contributes to information processing.
That is we have unknowns that might increase or decrease estimates of computational demands of a functionally equivalent ANN. Not everything that happens in the brain contributes to information processing.