Olfaction

Detection and processing of volatile chemical stimuli.

An olfactory sensory neuron is a neuron that detects odorant molecules and sends an electrical signal toward the brain. Receptor-bearing sensory endings sample chemicals at the nasal surface, while the axon carries the resulting output toward the olfactory bulb. Detection and interpretation are therefore distributed across peripheral cells and central circuits.

Genetically labelled receptor-expressing neurons allowed investigators to trace where their axons converged in the olfactory bulb. Receptor-swap experiments further tested how receptor identity contributes to that projection pattern. ^[ref] This connects molecular recognition to circuit organization without implying that a single active neuron uniquely identifies every odour: an odour can recruit a pattern across receptor classes.

Olfaction involving food volatiles reaching the nasal cavity from the mouth through the nasopharynx. It contributes to flavor and often to oral attribution. Changing this route can alter transport and peripheral stimulation as well as object context.

Olfaction involving odorants entering the nasal cavity through the nostrils. It commonly samples external sources; its relation to external object attribution is an empirical question rather than a definition of every possible experience.

A vertebrate brain structure receiving projections from olfactory sensory neurons.

A local site of converging sensory axons and interactions with postsynaptic cells. Molecular identity and other developmental mechanisms contribute to targeting.

A receptor involved in detecting odorants. Receptor identity is one component of the mapping from molecules to neural and behavioural responses.