Olfaction, or the sense of smell, remains largely a mystery to scientists. Although the basic processes, structures, and components involved in the olfactory system have been identified, the ability of smells to trigger feelings and memories and exactly how the brain identifies odors continues to be a source of investigation. In 2004, two physicians, Linda B. Buck and Richard Axel, won the Nobel
. Prize in Physiology and Medicine for their research involving the olfactory system.Olfaction involves the transformation of chemical information into neuronal activity in the brain. Most mammals and reptiles possess two-part olfactory systems: a main olfactory system and an accessory olfactory system; however, humans possess only the main olfactory system.An enhanced sense of smell is a condition called hyperosmia. Overall, women have better-developed olfactory skills than do men. Women experience an increased sense of smell during ovulation which is even more exaggerated during pregnancy.Side effects of some medications may include increased smell sensitivity. Cluster/migraine headaches and seizures can also cause heightened olfaction, as well as certain diseases. For instance, sufferers of Addison's Disease, chronic fatigue syndrome, multiple chemical sensitivity and cystic fibrosis experience a heightened sense of smell due to changes in production levels of certain hormones. Traumatic head injuries and other neurological abnormalities may also cause hyperosmia on a temporary or intermittent basis.Hyperosmia is a difficult condition to diagnose, but is of much interest to sensory scientists because of its relative rarity. Other olfactory disorders are much more common. These range from hyposmia, a decreased ability to detect smells, to agnosia, where smells can be detected, but not identified. These syndromes and other distortions in the olfactory sense are more likely to be associated with head trauma, chronically inflamed nasal passages, endocrine problems, inhaled-drug use and degenerative diseases such as Alzheimer's and Parkinson's disease.More reference links: http://emedicine.medscape.com/article/861242-overview#aw2aab6b2 http://nba.uth.tmc.edu/neuroscience/s2/chapter09.html
