Neuromodulation in Olfaction

Sensory systems have the ability to extract and synthesize environmental cues and form perceptions. However, perceptions and behavioral outputs to even the same signal vary depending on the internal state and experiences of the animal. Neuromodulation, defined as a biophysical process of modulating the computation performed by a neuron or neuronal network, is critical in adjusting sensory inputs and producing behavioral outputs. The olfactory system provides us with an excellent model system to study state-dependent neuromodulation of sensory perception. In flies and rodents, neuromodulators such as acetylcholine (Ach), norepinephrine (NE), octopamine (the insect counterpart of mammalian NE), serotonin (5-HT), dopamine (DA) and a variety of peptides play important roles in odor detection, habituation, discrimination, learning and memory. At the network level, computer modeling and experimental data suggest neuromodulation of cellular properties leads to a variety of effects such as increasing signal to noise ratios, sharpening receptive fields, scaling sensory input, promoting network oscillations, signal transmission, and plasticity. In this research topic, the most recent advances in our understanding of neuromodulation at cellular and circuitry levels will be presented. Technical approaches will include those of electrophysiology, optical recording, optogenetic and molecular biology. Theoretical work using computer modeling will also be presented. How neuromodulators affect odor perception and behavior will be discussed in the context of their cellular functions.