Olfactionrelated

Olfaction-related refers to anything pertaining to olfaction, the sense of smell. In biology, it encompasses the detection, transduction, processing, and perception of odorant molecules, as well as the anatomy, physiology, genetics, and clinical aspects of the olfactory system.

Anatomy and transduction: The olfactory system begins with the olfactory epithelium in the superior nasal cavity, containing olfactory receptor neurons with cilia that express a large repertoire of odorant receptors, which are G protein-coupled. Odorant molecules bind to receptors, activating Golf and adenylate cyclase III to raise cAMP, opening ion channels, and generating a receptor potential. Axons from these neurons project to the olfactory bulb, converging on glomeruli that map to receptor families. From the bulb, signals reach primary olfactory cortex regions such as the piriform and entorhinal cortices, with connections to the amygdala and orbitofrontal cortex.

Perception and coding: Odors are encoded combinatorially by patterns across many receptors, enabling discrimination among vast odorant spaces. Similar odorants can activate overlapping receptor sets, and perception emerges from the integration of sensory input with memory and context, influencing flavor, emotion, and behavior.

Neuroplasticity and development: Olfactory neurons and their projections exhibit plasticity and turnover, with ongoing neurogenesis in the epithelium and sometimes in the olfactory bulb, contributing to learning and adaptation to new odors.

Clinical relevance: Loss or reduction of smell (anosmia or hyposmia) can affect safety and quality of life and may arise from infections, trauma, sinus disease, or neurodegenerative conditions. Assessment uses olfactory tests; management includes addressing underlying causes and olfactory training.

Research and applications: Areas include receptor deorphanization, genetic variation in smell, and the development of artificial olfactory systems, with applications in fragrance, flavor science, and sensory therapies.