Mechanisms of Chemical Communication

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The general goals of this project are to understand individual recognition by scent in animals and, eventually, to use this as a way to understand the functional organization of the olfactory system in the brain as well as aspects of social memory. In this project, Dr. Johnston will investigate how animals communicate by scent. In particular, he will study a phenomenon known as scent over-marking, in which one animal deposits its scent in the same places as another. Preliminary results suggest that, by doing so, one animal can mask the information in scent deposited previously by another individual, suggesting that over-marking has competitive functions. Using golden hamsters in a variety of behavioral tests, Dr. Johnston will attempt to (1) document such competitive functions of over-marking in the social lives of animals, (2) characterize the special perceptual mechanisms that allow animals to decipher information from places that have been marked by several individuals, and (3) investigate how animals use information about individuals in such marks to guide their social behavior. These experiments have importance for at least three domains of science, and may have some practical implications as well. First, olfactory communication and scent-marking are important in the lives of most mammals, a few birds, most reptiles, some amphibians, and a huge number of invertebrates, yet we still understand little about it. This research promises entirely new insights into how animals use scent to communicate with one another and thus to regulate their social interactions. This new knowledge would help us to understand such aspects of behavior as territoriality, dominant-subordinate interactions, mate choice and competition for mates, and social recognition. Thus, it could eventually have practical implications for how to better house animals in captivity in labs and zoos, or to manage their behavior in households, and could even be helpful in wildlife management. Second, these experiments should give us new insights into the sense of smell by characterizing heretofore unsuspected sensory-perceptual abilities by which animals can extract information about one individual from complex mixtures of scent from two or more individuals. Third, the experiments will provide new knowledge and new behavioral paradigms that can be used as models for investigating the brain mechanisms underlying both the sense of smell and more general processes such as individual recognition and memory.