Cellular and network processes of noradrenergic modulation in the olfactory system.

Norepinephrine (NE), a central neuromodulator, influences sensory processing at the behavioral and physiological levels, potentially by regulating signal-to-noise ratio in sensory neural networks. To understand neuromodulatory function at the perceptual level, one must understand the neural mechanisms underlying these effects. In this review, we illustrate this process using the olfactory system as a model system. We discuss basic computations in the olfactory system and their modulation by NE. We review known cellular effects of NE in the olfactory bulb and cortex and how these effects modulate olfactory computation. We then illustrate how computational modeling can relate cellular and perceptual data using the example of NE modulation of odor detection thresholds.