The olfactory system, like other sensory systems, must decipher both identity and intensity of stimuli detected in the environment. Olfactory processing likely occurs at several levels from the periphery to the brain, such that higher order processing regions integrate information from sensory neurons with associational and state-dependent cues to drive behavior. However, recent studies show that sensory neurons are not passive relays of olfactory information [14**,15**,16–18,19**,20]. Surprisingly,
genetic analyses in worms, flies and even mice have shown that certain neuropeptides modulate odor
responses at the level of the olfactory sensory neurons. By depressing or facilitating the activity of sensory neurons, neuropeptides increase the ability of sensory neurons to transmit information about wide ranges of odorant concentrations. This fine regulation could allow the animal to accurately localize an odor or food source.