Beverly J. Cowart, Ph.D. - US grants

The chemical senses serve a major function in influencing food selection and intake and therefore nutritional status. The purpose of this research program is to delineate the psychophysical characteristics of an understudied chemosensory system, that which mediates oral chemical irritation, or the "common chemical sense." Proposed experiments include examination of 1) differences among stimuli regarding the rate of growth of sensation intensity with concentration and the rate of sensation decay over time, 2) potential qualitative discrimination in this sensory system, 3) interactions of oral irritation with the classical gustatory qualities, 4) differences in sensitivity across the oral epithelium, 5) spatial summation, 6) the time course of sensory adaptation and possible desensitizing effects of some oral irritants, and 7) the relative contributions of facial nerve (chorda tympani) and trigemimal nerve afferents to the perception of irritation on the dorsal tongue surface. This latter comparison will be achieved using patients with unilateral chorda tympani transection, stimulating each half of the tongue separately. A final underlying theme will examine differences in perception among individuals with chronic high dietary levels of spice-derived irritants, which are reported to alter oral sensitivity. The proposed experiments should provide information basic to the understanding of any sensory system: psychophysical functions, the nature of adaptation and inhibition, and differences in sensation due to different spatial and temporal parameters of stimulation. These studies should pave the way for future correlation of perceptual characteristics with physiological observations (e.g. relation of sensation to receptor types) or with chemical characteristics of oral irritants (e.g. structure-activity studies). These data should also provide a picture of "normal" common chemical sense function, against which future studies of disordered oral sensation may compare results.

The Sensory Core provides a stable center for the ongoing activities of the CCRC and support to the individual Projects associated with the Center. The Core assumes major responsibility for the assessment of chemosensory function and dysfunction. It has established a clinic to evaluate referred patients with complaints of abnormal smell or taste function, providing psychophysical, otolaryngological and oral health assessments. Through the clinic, we have been able, for example, to (1) characterize smell and taste disorders in a large sample of patients, (2) assess the clinical utility of various methods of chemosensory testing and develop procedures to provide new insights into the nature and degree of chemosensory dysfunction, (3) assess the impact of age on chemosensory dysfunction, and (4) establish a systematic patient follow-up program, which is beginning to yield information that will both broaden our understanding of various forms of chemosensory dysfunction and enable us to provide patients with accurate prognostic information. We propose to continue and expand these types of general clinical activities, building on projects begun in the current funding period (e.g., the development of a clinical test of retronasal olfactory function and of a questionnaire to assess the impact of chemosensory dysfunction on quality of life). The Core facility also serves a general resource for the CCRC and is critical to the success of clinical research projects, providing access to, and consistent chemosensory and otolaryngological evaluation of, defined patient populations. In the proposed renewal, the Core plays a key role in identifying, recruiting and testing patients and/or normal control subjects for individual Projects of the CCRC, and in coordinating Project activities.

The Sensory/Medical Core provides a stable center for the ongoing activities of the Chemosensory Clinical Research Center (CCRC) and support to the individual Projects associated with the Center. The Core assumes major responsibility for the assessment ofchemosensory function and dysfunction, and is key to the recruitment and consistent psychophysical and medical evaluation of patients participating in specific Projects. This Core also provides data management and statistical support to the Projects, and its laboratory, testing facilities and databases (which comprise extensive demographic, psychophysical and medical information on both normal and patient populations) are available to Project investigators. Finally, the Core serves as the focal point of interactions between basic research scientists at Monell and the clinical faculty of The Thomas Jefferson University. In addition, the Sensory/Medical Core maintains a clinical facility for the evaluation of referred patients who have primary complaints of abnormal smell or taste function. This Clinic serves to ground our CCRC and its investigators in the phenomenon that is at the heart ofchemosensory clinical research namely, chemosensory dysfunction. Through the operation of the Clinic, we have been able to assess the clinical utility of various methods of chemosensory testing, as well as to investigate such issues as the impact of chemosensory dysfunctions on patients, the etiologies of chemosensory dysfunctions and, through our comprehensive longitudinal follow-up program, the prognoses for chemosensory dysfunctions. In the proposed funding period, the Core's direct support to all Projects in the form of recruiting, scheduling, and evaluating participants is greatly expanded over previous years. We will also, however, continue our general clinical evaluations, given the great value of this work in yielding insights that serve to direct future research.