Section: Rotations

Thomas Schoenfeld, Ph.D.

Academic Role: Research Associate Professor

Faculty Appointment(s) In:
   Physiology

Potential Rotation Projects

Project #1: A fovea in the nose? The ORNs present a spatial map of the nose to the olfactory brain, by way of the pattern of their axonal projections, not unlike the manner by which the retina is mapped onto the visual brain. We are testing the hypothesis that, like the retinal map, this "nose" map provides the brain with a means to extract sensory information with different degrees of resolution and sensitivity. We are using several experimental approaches to testing this hypothesis. One is to characterize variation in the convergence of ORNs onto brain targets across different dimensions of the spatial map, using anatomical techniques such as tract-tracing (using lipophilic dyes and neurotropic viruses), stereology and similar quantitative methods, and 3D solid modeling of the nose and olfactory bulb, in mice genetically engineered to label odorant-receptor gene-specific populations of ORNs.  Another is to look for spatial patterns in the response of olfactory neurons in the nose and brain to odorant stimulation, and to examine the relationship of these patterns to the characteristics of odorant migration through the nose, using electrophysiology, functional neuroanatomy (immediate early gene activation) and gas chromatography, again in gene-targeted mice. 

Project #2:   In search of long-lived olfactory receptor neurons. ORNs are generated throughout life by a resident population of perpetually dividing stem and progenitor cells. While the rate of their proliferation is greater than that found elsewhere in the nervous system, and is consistent with their being the only neurons in the entire body to be directly exposed to the potentially lethal external environment, such neurons are amazingly short-lived, undergoing programmed cell death within 30 days. Thus, we seek to identify and examine further factors that may extend their lifespan in situ beyond the defacto 30 days. Such factors include: (1) the enhanced availability of synaptic sites in the olfactory brain following the massive degeneration of ORNs, as induced by surgical olfactory nerve cuts and other techniques, and (2) enhanced titers of neurotrophic factors such as platelet-derived growth factor and neurotophin-3 that may normally promote the survival of ORNs born in adulthood but also regulate the numbers that can survive.

Keywords: Neurobiology, Organisms - mouse, Sensory Systems, Imaging and Microscopy, Physiology

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