While I agree that 10^17 seems like a more accurate number, don’t forget that each neuron contains ~10^5 synapses which all process at timescales of 10s of microseconds. This gives you an additional factor of 10^9
The 10¹⁷ includes that factor. 10¹⁰ neurons by 10⁵ synapses by 10² Hz. It seems unlikely to me that the meaningful temporal resolution is going to be 1000x that of the firing rate, but if you want to add a factor of 10 or so I wouldn't object.
