Peripheral Mechanisms of Perceptual Adaptation and Odor Masking
Adaptation, common to all senses, is the process by which sensory systems filter ongoing or repeated stimulation and, by doing so, increase the salience and detection of new, or novel stimuli. Because the natural world is filled with volatiles, it is rare that an odor is ever experienced in isolation and it is likely that the perception of most, if not all, odorants is determined, at least in part, by the process of adaptation. How odor adaptation is accomplished reflects a series of complex physiological processes, acting at multiple levels within the olfactory nervous system. Our work in this area involves the development and use of custom-designed olfactometers which allow for the precise timing and delivery of simultaneous odorants. Using these techniques, we have been able to measure the onset, and offset (recovery from adaptation, or disadaptation) time course of adaptation.
Auditory Selective Attention
More traditional theories suggest that selective auditory attention is mediated by central mechanisms in the brain, above the level of the thalamus. Descending, efferent pathways, however, do exist and connect the primary auditory cortex with the outer hair cells in the cochlea – providing a pathway by which attention can physiologically influence the most peripheral aspects of the auditory system. Our studies, employing distortion product otoacoustic emission measures in human listeners, have shown that attention, and attentional load, have significant affects on cochlear function.
Changes in Olfactory Function with Neurodegenerative Disease
A growing body of research suggests that one of the first signs of neurodegenerative disease is a deterioration in the sense of smell. New translational research projects in our laboratories, working with both human and animal models, are investigating the pathophysiological changes underlying the degradation in smell in both Alzheimer’s and Parkinson’s Diseases. Working with Drs. Barry Setlow and Jennifer Bizon, Department of Neuroscience, we are characterizing changes in olfactory behavior with cognitive disorders in both transgenic mice and in an aging rat model. Concurrent research, in collaboration with Dr. Catherine Price, Department of Neuropsychology Movement Disorders Clinic, we are investigating changes in smell as biomarkers for the onset and progression of idiopathic Parkinson’s Disease.
Plant Volatile Interactions
This project is a collaboration with Drs. David Clark, Harry Klee and Denise Tieman of the Plant Innovation Program in the Institute for Food and Agricultural Sciences (IFAS). The aim of this project is to characterize the importance of different plant volatiles in determining the overall taste and smell of tomatoes. While the overall aroma of a tomato is defined by over 400 volatiles, only 15-20 are thought to contribute significantly. The most important of these chemicals are also volatile signatures of essential amino acids.
Our studies combine human and animal psychophysics; human studies investigating the interaction of different volatiles and mouse studies investigating the effects of manipulation of the diet (eAA depletion) on food choice preference.
Mechanisms of Hearing with a Cochlear Implant
When auditory receptors, the inner and outer hair cells of the cochlea, are severely damaged or destroyed by disease or trauma, electrical stimuli delivered through implanted electrode arrays can restore some semblance of hearing. Our work has involved