Odors learn

Hammer M. and Menzel R. (1998) Multiple sites of associative odor learning as revealed by local brain microinjections of octopamine in honeybees. Learn. Mem. 5, 146-156. 

Peele P, Ditzen M, Menzel R, Galizia CG (2006) Appetitive odor learning does not change olfactory coding in a subpopulation of honeybee antennal lobe neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol [A] 192 1083-1103... 

Signature Mixtures Variable Individual, family, colony odors Learning required... 

Healthy newborn human infants are endowed with a highly sensitive sense of smell. Moreover, there are documented accounts of olfactory learning during the early postpartum period. In the present chapter, we present a brief overview of the relevant research literature and suggest tentatively that olfactory learning may be facilitated by neurochemical activities associated with labor and delivery, and memory traces of odors learned shortly after birth may be retained more efficiently than early postnatal memories involving other sensory modalities (i.e., vision and audition). 

The vomeronasal organ (VNO), located in the nose, is a small chemical sensing stmcture associated with odors and behavioral effects. The vomeronasal system, which is made up of the VNO and a portion of the brain s limbic system, is stmcturaHy independent of the olfactory and nervous terminalis systems in the nose. It may, however, interact with these systems in a manner dependent on prior experience or learning, and therefore be direcdy related to the association of smells and experiences. This independent chemosensory system in the nose may prove to open doors to new learning associated with the sense of smell and human behavior. 

It was thought previously that there were no inborn odor preferences that these are learned from experience. However, studies at the MoneU Center have indicated that flavors consumed by a mother and transmitted into the milk influence the feeding behavior of her infant. When mothers consume gadic, their infants feed longer than when no gadic is consumed (7). 

Odors play a much greater role in human behavior than previously thought. The sense of smell provides a direct link with the function of the brain therefore, the further study of olfaction can only advance the learning of causes and effects of stimuli to the brain. 

Olfactory receptors have been a subject of great interest (9). Much that has been postulated was done by analogy to the sense of sight in which there are a limited number of receptor types and, as a consequence, only three primary colors. Thus attempts have been made to recognize primary odors that can combine to produce all of the odors that can be perceived. Evidence for this includes rough correlations of odors with chemical stmctural types and the existence in some individuals having specific anosmias. Cross-adaptation studies, in which exposure to one odorant temporarily reduces the perception of a chemically related one, also fit into this hypothetical framework. Implicit in this theory is the idea that there is a small number of well-defined odor receptors, so that eventually the shape and charge distribution of a specific receptor can be learned and the kinds of molecular stmctures for a specified odor can be deduced. 

Whitney G., Alpem M. and Dizinno G. (1974). Female odors evoke ultrasounds from male mice. Anim Learn Behav 2, 13-18. 

Schellinck, H. M., Arnold, A., Rafuse, V. (2004) Neural Cell Adhesion Molecule (NCAM) null mice do not show a deficit in odor discrimination learning. Behav. Brain Res.152, 327-334. 

Smotherman, W.P. (1982) Odor aversion learning by the rat fetus. Physiol. Behav. 29, 769-771. 

Sullivan, R.M. and Leon, M. (1987) One-trial olfactory learning enhances olfactory bulb responses to an appetitive conditioned odor in 7-day-old rats. Brain Res. 432, 307-311. 

Varendi, H., Porter, R.H. and Winberg, J. (1996) Attractiveness of amniotic fluid odor evidence of prenatal olfactory learning Acta Paediatr. 85, 1223-1227. 

Much of the previous research on the role of early olfactory experience on adult odor preferences has used the approach of cross-fostering young pups to a lactating dam of a different species (D Udine 1983). Thus, a shift in preference toward odor of the foster parent indicates that species-specific odors are learned via the early experience with the foster parent. Several important themes have emerged from this literature that shed light on the degree to which species preference is learned during early life. 

Taken together, this body of work demonstrates that adult behavioral responses to social odors are shaped by early olfactory experience. Indeed, heterospecific or artificial odor cues associated with the rearing environment acquire attractive properties that can last into adulthood in many rodent species. Furthermore, early experience with opposite-sex odors appears to be critical for the normal development of appropriate behavioral responses to sexual odors in mice and hamsters. Importantly, the behavioral plasticity observed using these different experimental approaches may all be mediated by a classical conditioning model of olfactory learning. The experience-dependent development of odor preference in rodents therefore provides a powerful model for understanding how the olfactory system recognizes and learns the salience of social odors, a function that is critical for the appropriate expression of reproductive behavior. 

Johnson, B. A., Woo, C. C., Duong, H., Nguyen, V. and Leon, M. (1995) A learned odor evokes an enhanced Fos-like glomerular response in the olfactory bulb of young rats. Brain Res. 699,... 

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