Many terrestrial and aquatic organisms use their sense of smell to locate food, identify mates, and find suitable habitats by tracking odors dispersed within a turbulent plume. Measurements of chemical plumes show that odorant concentrations are filamentous and the instantaneous spatial and temporal structure of a plume greatly depends upon the turbulent wind or water flow field. These odor signals are sampled by the olfactory organs of animals navigating in a plume and presumably provide information about the odor source location. Chemical detection and tracking behavior is not only important ecologically, but can also provide insight into the design of artificial sensors. Many animals (insects, crustaceans, etc.) actively sample odor-laden fluid using appendages (antennae or antennules) that contain rows of chemo- and/or chemo-mechano sensilla (aesthetascs). The crayfish, Procambarus clarkii, will act as a model system for the detailed analysis of flow field effects and odorant exposure on neural responses. A combined particle imaging velocimetry (PIV) and planar laser induced fluorescence (PLIF) system will measure simultaneous fluid structure and odor concentrations within a large scale plume, created within an 11 m long recirculating flume. This information will then aid recreation of the detailed flow and odor dynamics surrounding an antennule and individual aesthetascs within a specially designed micro-flow chamber. Electrical responses of brain neurons to odors restricted to different regions along the antennule sensor array will determine how spatial and temporal dynamics may regulate central processing of odor input, and the extent to which hydrodynamic inputs to one region of the antennule may modify the central response to odors detected at a separate location. The ease of access to the mechano- and odor-detecting sensilla, and the ability to keep the antennule-brain preparation alive for many hours during monitoring, make this animal ideal for electrophysiological investigation of olfactory processing. This work will be supported by theoretical and numerical analysis, as well as scaled model experiments to determine how flicking kinematics and antennule morphology affect convective-diffusive transport, and physical-chemical capture of odors by crayfish antennules. The interdisciplinary team with expertise in optical flow measurement techniques, experimental and computational fluid mechanics and sensory and single-cell neurophysiology will study the complex interaction between chemical plume structure and sensory ecology of all animals living in aquatic and terrestrial environments. During this study the PIs will organize an international symposium on Sensors and Sensing in Biology and Engineering, integrating the results into graduate and undergraduate courses taught by the co-PIs and to an existing NSF-funded education initiative at UVa aimed at introducing science and engineering concepts and principles to children in the middle schools using especially designed Engineering Teaching Kits (ETK). Finally, the PIs will develop an intellectually accessible, sensors-based ETK with an interdisciplinary senior year team, aimed at female, minority and disadvantaged children.
This research is cofunded by the BIO Directorate.
