The Physics of Chemoreception: Interactions of Fluid Flow and Chemosensory Morphology

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Sensory reception of a stimulus often involves structures or processes called "perireceptor" features that affect the sensory signal before it gets access to the receptor cells. Examples include the lens of the eye or the eardrum of the ear. In chemoreceptor systems for taste and smell, there is a new interest in how solubility, microscale fluid mechanics, diffusion, and chemical reactivity affect responses to chemical stimuli. The lobster antennule is a good example of a chemoreceptor working in a fluid; this organ, like a small antenna, is covered with fine bristles and chemoreceptors to sample, in time and space, odor plumes that come by in the water. The lobster "flicks" the antennule as an analogy to "sniffing" with a nose, as the physical flick displaces the water mass trapped around the bristles with a new sample water mass. This project uses sophisticated stimulus delivery techniques, 3-D video analysis, and novel sensor electrodes, working with this different appendages in the lobster as a model system, to provide novel quantitative data on temporal and spatial features in the microscale environment around the receptor cells. Boundary layer and physical transport processes interact with the detailed structure of the receptor organ to provide "filtering" of the input signals, and it is this filtering that helps extract information from the environment in a way adaptive for the animal. The morphology and sampling behavior of different chemosensory appendages will be analyzed to see what role the differences play in determining the spatial and temporal analysis of chemical signals. Results from this work will lead to new understanding of how specialized chemoreceptors detect patterns of stimuli, and how such chemosensory organs have evolved to detect particular kinds of environmental signals. The impact will extend beyond chemosensory neuroscience to behavioral science, evolutionary biology, fluid mechanics, and possibly also on marine aquaculture.