Olfaction odorant recognition

Obsession, 103,105, 123,125-126,139, 270 Odor effects diagram, 151 Odor intensity, related to concentration, 247-249 Odor strength, inherent, 163. 166 Odor value, 163,166, 249-259 Odor volume, 152. 153. 162 Olfaction anatomy, 76 evolution, 75 and odor recognition, 25 Olfactometer, 244 Olfactory sensitivity, see Sensitivity... 

Olfaction is of primary importance for social recognition in mammals, including mice. Thus mice use odors to distinguish sex, social or reproductive status of conspecifics (Brennan and Zufall 2006 Brown 1979). In addition, odors have been shown to facilitate the display of sexual behavior (e.g. Thompson and Edwards 1972) and to induce neuroendocrine responses (e.g. pregnancy block in female mice Brennan and Keverne 1997). 

A fundamental concern of psychophysicists working on olfaction has been the determination of the odor thresholds of a broad array of substances. A distinction must be made between the detection threshold, which is the lowest concentration at which significant detection takes place that some odorous material is present, and the recognition threshold, which is the lowest concentration at which an odorant can be recognized for what it is. 

Most olfaction models in the literature are far too simplistic and too mechanical in nature, and none of them have succeeded in accounting for all of the observations about olfaction. As described, recent advances in our understanding have confirmed that odor perception, as predicted by Polak (19), starts with a combinatorial mechanism at the receptor level (1) and involves pattern recognition in the higher brain (4). No single odorant-receptor interaction will be the sole determinant of odor percept, and even knowledge of the pattern elicited at the olfactory bulb is insufficient to enable prediction of the cortical image of odor. Therefore, structure/odor models are and, for the foreseeable future, will remain statistical tools rather than mechanistic indicators. 

H. M. clearly understands how to discriminate chemical stimuli. His impairment limits only his recognition of odors, but no other aspect of his sense of smell. He is "odor deaf," by analogy to stroke victims who can read and write and retain an intact sense of hearing but cannot recognize words aurally (and are said to be "word deaf ) (Takahashi et al., 1992). Based on the evidence discussed so far, H. M. s behavior does not satisfy the fourth of the guidelines for olfaction. 

The odor of HCN, likened to that of bitter almonds, has been stated to be an important clinical clue in the recognition of acute CN poisoning. A detection range of 0.5-5.0 ppm has been suggested (Kulig and BaUantyne, 1993). However, it needs to be noted that some individuals are not able to detect the odor of HCN by olfaction. This CN anosmia, present in 2% 5% of different ethnic... 

ADAPT has been developed and used by Jurs in a wide range of S AR applications. In the field of olfaction, these include the correlation of odour intensities for 58 structurally and organoleptically diverse odorants (Edwards and Jurs, 1989), and the investigation of the relationship between molecular structure and musk odour (Jurs and Ham, 1977 Ham and Jurs, 1985 Narvaez et al., 1985). To date, no one has used pattern-recognition techniques in the study of muguet odorants. 

It has been observed that the discriminatory capabilities of human olfaction are tremendous It was estimated that an untrained person could differentiate up to ten million odors, perhaps even significantly more than that. Information theory then shows that in order to encode the qualities of ten million odors in a simple binary mode (Monoosmatic components on or off, their intensity, albeit important, is in this connection disregarded) only 2h to 27 specific profiles, disregarding possible and probable redundancies, and therefore the same number of complementary receptor sites would be required. Assuming furthermore that said redundancy, in which the informational modalities of two different specific receptor sites of two different olfactory neurons are confluent in one collector cell and therefore contribute to the expression of only one monoosmatic component is indeed operational it becomes necessary to increase the total number of types of specific receptor sites to 2k-30. This means that only 2U-30 specific detector proteins are required for structure recognition in the transduction process. This compares to about UOOO enzyme systems in different stages of activity estimated to be present in a cell any time. 

These results cannot be explained with any of the older theories of olfaction whereas the Enzyme Model of Olfaction not only can do that effortlessly, but actueLLly allows to predict these effects on the basis of generally accepted principles of molecular biochemistry. The concept of "STRUCTURE RECOGNITION AS PERIPHERAL PROCESS IN ODOR QUALITY CODING" represents only the special application of a more general mechanism of structvure recognition in peripheral processes to the problems of quality coding in olfac-r tion. 

Olfaction is the primary modality for social recognition and communication in nocturnal rodents (Johnston, 1983 Halpin, 1986, 1991). For example, most mammals that have been tested discriminate between the odors of individual conspecifics that are not close relatives (e.g., Johnston, et al., 1993 Johnston Jernigan, 1994 Todrank Heth, 1996) and many species may use these individually distinctive odor cues for recognition of kin versus non-kin as well (e.g. Block, et al., 1981 Hepper, 1983). Most secretions that are individually discriminated also contain information about other attributes of the individual, such as the sex, reproductive state, and species of the odor donor (Johnston, 1983 Heth, Beauchamp, Nevo Yamazaki, 1996). 

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