The response of individual central neurons to sensory inputs is unreliable when observed trial to trial.
Receptive fields are unreliable on a single trial, but sensory perception is reliable.
At the same time, our understanding of central circuitry now suggests not a simple feed forward passage of information, but rich local circuits and heavy feedback. And finally, the nature of communication between neurons now looks not only to additive excitation and inhibition, but to an incredible palatte of influences on multiple time scales.