RUI, ABR: Olfactory Compensatory Plasticity

Randolph-Macon College, Ashland VA

Investigators

Abstract

The ability of the nervous system to change in response to experience, i.e., to exhibit 'plasticity', is a long-standing topic of inquiry in neuroscience. In particular, the role of ongoing sensory stimulation for the normal development and maintenance of sensory systems is a perennial area of interest. Knowledge about these processes for the sense of smell lags behind the other senses, not least because of the difficulty in physically controlling an odor stimulus. This project advances our understanding of stimulus-induced changes olfactory processing and other mechanisms of smell, as well as sheds light on the tendency of physiological systems, like olfaction, to operate in a relatively stable equilibrium between interdependent elements, the process known as homeostasis. The olfactory periphery affords an excellent model where all components of a homeostatic system can be ascertained. Besides advancing our understanding of the sense of smell and sensory plasticity, the studies may suggest design elements for incorporation into chemical detection devices ('electronic noses') with applications in robotics, disease diagnosis, and bomb detection. Integrated with the research project is student-mentoring, participation-broadening, and public outreach through active involvement of undergraduates, including members of underrepresented groups, and the development of an exhibit at a local children's museum. These aspects of the project improve human resources in Science, Technology, Engineering, and Mathematics, and, via the museum, may engage thousands of school students annually. This project addresses the universal problem of how our senses adjust to long-term changes in the stimulus environment. Such adaptability allows sensory systems to match the dynamic range of their receptors to the array of stimuli in the environment, which can vary dramatically in time and space. Little is known about the cellular mechanisms of these homeostasis-like processes. The Investigator and his colleagues have discovered a phenomenon in the olfactory periphery termed compensatory plasticity that has the signature of such a process. In the olfactory epithelium, odor deprivation causes an up-regulation of the transduction cascade and enhancement of physiological responses that seemingly compensate in low stimulus environments. The previous work allowed only binary control of the odor environment (i.e., deprivation or no deprivation). In the current project, the responses of the olfactory system to odor stimulation history is examined using olfactometric methods that allow broader control of odor environments, including the type, complexity, concentration, and timing of odor exposure. The dependent measures include transcriptomic, histological, physiological, and behavior endpoints, allowing a holistic analysis of compensatory plasticity that lays the groundwork for a mechanistic understanding of this process. Results from these studies advance our understanding of olfactory plasticity as well as illuminate mechanisms of neural plasticity and homeostasis