Taste critically guides ingestive decisions that impact nutritional status and can lead to health problems in humans, such as obesity, diabetes and coronary heart disease. Thus, understanding mechanisms for taste is critical for defining how sensory factors impact human health and well being. Taste experience typically occurs in unison with other oral sensations, such as texture and temperature (somatic sensations). Taste perceptions can be modified by oral temperature, indicating the mechanisms of taste and thermosensation are linked. Taste neurons in the brain stem respond to oral temperature and, thus, are suited to process integrated taste and thermal input. The long-term goal of the proposed research is to define mechanisms of multimodal oral sensory processing in the brain stem. Using anesthetized mice, electrophysiological recordings will be made from individual brain stem neurons sensitive to both taste and oral thermal inputs.
Specific Aim #1 will test the hypothesis that oral temperature influences gustatory neural codes. Oral responses to cooled and warmed taste stimuli will be recorded and analyzed to define how temperature impacts neural representations of gustatory quality and intensity information.
Specific Aim #2 will test the hypothesis that taste neurons show similar sensitivities to tastes and temperatures of similar hedonic valence. These projects will elucidate the ability of taste neurons to signal oral somatic information and have implications for the oral sensory system to be integrated and not a collection of discrete modalities. Analyses of neural responses to concentration series of hedonically different taste stimuli and innocuous and noxious oral temperatures will evaluate this idea.
Specific Aim #3 will test the hypothesis that upon initiating oral sensation thermal input to taste neurons is transmitted before taste. Timed sequencing may underlie interactions between temperature and taste - fast, early thermal stimulation could prime taste networks for modulation of subsequent taste input. Response time course data for individual neurons and neural ensembles will be analyzed to evaluate if taste and thermal interactions depend on the sequencing of sensory input. Overall, these projects will shed light on multisensory neural processes potentially involved in aspects of flavor integration and ingestive decisions.
The proposed research aims to define how interactions and relationships between taste and oral temperature are represented by the electrical activities of neurons in the brain. Understanding this concept will be important for understanding the neural mechanisms of taste and oral sensory perception and how taste processes guide ingestive decisions influencing nutritional status and health.
