Maybe a lifetime is an action potential. The "input" is provided because the precise configuration designating "existing" physically real sense impressions of a physically possible universe is necessary for such a configuration to even exist at all,- to the limits of the knowledge of that subjective being's imagined experience. That limit makes it still statistically more probable than the entire history of a universe happening the exact way required to produce that moment.
If you can reproduce all the inputs, you can theoretically do it with a single neuron. Like a hologram of a higher dimensional object encoded onto a lower dimension. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3741678/
The problem can be solved by considering that only one moment needs to be statistically accounted for at a time and then the next moment becomes statistically just as likely as the one before, associated only by anticipation and memory, existing completely independently however by its own random nature. The frequencies of conscious experience range only 5-50 per second, much much less of a data burden than say a planck level simulated reconstruction of an entire physical universe exactly required to create those moments for that lifetime. http://discovermagazine.com/2007/jun/in-no-time