Sensory responses at both the neural and the behavioral level are highly variable, creating the appearance of a nervous system that is inherently noisy. Here, I will present my recent whole-cell patch-clamp electrophysiology results from awake, behaving mice, which show that carefully tracking the state of the animal (primarily using pupillometry) dramatically ‘de-noises’ auditory cortical processing and auditory signal detection behavior. I will then show two-photon imaging data of genetically-encoded calcium sensors selectively expressed in noradrenergic or cholinergic axons in cortex, which reveal distinct temporal relationships of activity in these neuromodulatory systems to state changes tracked by the pupil. I will conclude with an outline of my future research direction proposing to study the cellular and synaptic mechanisms by which these same neuromodulators act as learning signals and reshape sensory responses, within the context of the awake state as a tractable dynamical system. This research direction pursues the hypothesis that the logic of brain circuits underlying perception and behavior may reveal itself if the dynamics of the awake state are carefully tracked and sufficiently understood.