Social odors

Mayeaux, D. J. and Johnston, R.E. (2004) Discrimination of social odors and their locations role of lateral entorhinal area. Physiol. Behav. 82, 653-662. 

Lundstrom, J. N. and Olsson, M. J. (2005) Subthreshold amounts of social odorant affect mood, but not behavior, in heterosexual women when tested by a male, but not a female, experimenter. Biol. Psychol. 70, 197-204. 

Abstract Sexual orientation influences human olfactory function. Following a brief review of the biological basis of homosexuality, this chapter explores exactly how olfactory function varies as a result of sexual orientation. Three separate areas of research are considered recent studies on the neural processing of social odorants by heterosexuals and homosexuals the influence of sexual orientation on the production and perception of body odours and the influence of female sexual orientation on menstrual synchrony. 

Petrulis, A., DeSouza, I., Schiller, M. and Johnston, R. E. (1998) Role of frontal cortex in social odor discrimination and scent-marking in female golden hamsters (Mesocricetus auratus). Behav. Neurosci. 112, 199-212. 

Brown, R.E. (1979) Mammalian social odors. Adv. Stud. Behav. 10, 107-161. 

Abstract Mate recognition is an essential component of successful reproductive behavior, and in rodent species, is primarily guided by the perception of social odors in the environment. Importantly, there is substantial evidence that species or sexual odor preferences may be regulated by early olfactory experience, although considerable variability in the plasticity of these behaviors has been observed. The current chapter summarizes what is known regarding the role of early olfactory experience in the development of adult odor preferences, synthesizing data across species, sex, and behavioral paradigms. 

As with many macrosmatic mammals, rodents have two separate chemosensory systems, the main olfactory system (MOS) and accessory olfactory system (AOS), which respond to social odors. Importantly, these sensory systems differ not only in their peripheral morphology and central projections, but also in the types of chemosignals that they process (Meredith 1991). Sensory neurons of the MOS, which are located in the main olfactory epithelium and project to the main olfactory bulbs, process volatile chemicals and can detect odors at a distance. In contrast, sensory neurons of the AOS, which are located in the vomeronasal organs (VNO) and project to the accessory olfactory bulbs, primarily process large, non-volatile chemicals and require contact for stimulation (Meredith 1991). 

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. 

Social odors have rarely been reported in birds. The respiration rate of wedge-tailed shearwaters Puffinus pacificus) increases in response to the odor of an unfamiliar conspecific (Shallenberger, 1975). Domestic ducks altered social and sexual behavior after bilateral section of the olfactory nerve, or after treatment with amyl acetate or ethyl acrylate (Balthazart and Schoffeniels, 1979). Some bird species are known for their strong characteristic odors. For instance. 

In mice, urine is the main source of social odors. Wild house mice (M. domcsticus) families over time build bizarre small posts of solidified urine by repeated marking (Hurst, 1987 Fig. 6.13). A mouse family is habituated to its own background odor, which permeates its living area. The ubiquitous family odor is dominated by the odor of the dominant male and identifies the home area to residents as well as non-residents. (When the author trapped 26 deer mice over... 

In human infants social odors are important from a few days after birth, as indicated by head turning in the direction of odors. In 1877, Darwin observed that an infant with its eyes closed would turn its head towards its mother when her breast was brought near. Darwin suggested that the infant might be attracted... 

In mammals, early experience with social odors will have lasting effects on odor preferences. We have to distinguishji/w/ (attachment ofyoung... 

Not surprisingly, much research in sharks, skates and rays has focused on the responses of sharks to human body odors. Human blood attracts sharks, while sweat does not, and urine was even slightly repellent (Tester, 1963). Practitioners use whale meat and mixtures of fish meal and fish oils as shark attrac-tants. In both carnivorous and herbivorous bony fish (Osteichthyes) smell deals with prey odors, social odors, and chemical stimuli in homing, and it is mediated by the first cranial nerve, the olfactory nerve. By contrast, taste serves in detection and selection of food and avoidance of toxic food, and it employs the facial, glossopharyngeal, vagal, and hypoglossal nerves. 

The influence of odors such as perfumes and fragrances on human behavior is assumed to he acquired, and the responses elicited depend on the often complex previous social experiences. The response will be altered if a laboratory experiment eliminates contextual stimuli (Kirk-Smith and Booth, 1987). Social odors include those of the well-known security blankets in toddlers, familiarly scented bed sheets in new surroundings, and treating insomnia with mother s axillary odor on handkerchief. Removal of bad body odors (diet, metabolism defects) that disrupt interpersonal harmony appears to be universal. 

Recent research has utilized the cell activation marker properties of c-fos, an immediate-early gene, to demonstrate the specificity and pathways of the accessory olfactory system. For example, social odors activate cells in AOB (Schellinck et al. 1993) and, more specifically, central nuclei of the accessory olfactory system regulate species specific mating behavior (Fiber et al. 1993). The complexity of olfactory and somatosensory... 

Brown, R. E., and Macdonald, D. W., 1985, Social Odors in Mammals, Clarendon Press, Oxford. 

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