Sense of smell: recognition and transduction of olfactory signals.

The primary processes in odour perception, i.e. recognition and transduction of olfactory stimuli, are mediated by the chemosensory olfactory neurons. Interaction of odorous compounds with suitable receptor proteins in the membrane of a subset of cells elicits chemo-electrical transduction pathways, including second messenger cascades and ion channels, that modulate the excitability of the sensory neurons, i.e. converting the chemical stimulus into electrical impulses. The encoded information is conveyed via the axons onto distinct glomeruli in the olfactory bulb. Olfactory sensory cells expressing the same receptor type are segregated spatially in a distinct zone of the nasal epithelium and converge their axons to one or a few distinct glomeruli. The emerging chemotopic maps are considered to be crucial for processing and encoding sensory information of olfactory stimuli.