Chemo-Hydrodynamic Signal Detection

Trustees Of Boston University, Boston

Investigators

Abstract

Odor plumes are generated by turbulent mixing of odor from a source of release with "clean" air or water. The result is a series of "flavored" eddies intermingled with non-flavored eddies. The spatial distribution of these flavored eddies contains a statistically reliable gradient of information that animals may use to locate distant odor sources. Therefore, they need sensors whose filtering capabilities enhance those signal parameters that provide the best spatial gradients. Both chemical and hydrodynamic dispersal patterns must be considered. Previous NSF funding supported experiments from which it was determined that for chemical gradients the concentration slopes of odor patches provide good directional information. Neither the equivalent hydrodynamic information nor to which degree these two signal features are actually used by animals and under which circumstances are known. The primary sensory processes of chemo-hydrodynamic signal detection will be studied. The lobster and its well-studied lateral antennule will be used as the model of choice for linking primary sensory information in both modalities. Electrophysiological recording of action potentials from the antennular nerve, which carries chemical and mechanical information to the brain, will be used. The excised antennule will be exposed to independently controlled chemical and hydrodynamic stimuli with high-resolution measurement of both. The chemical response properties of the antennule are relatively well known. Its hydrodynamic responsiveness now will be determined and the possibility of peripheral bi-modal signal processing will be explored. Any form of bi-modal chemo-hydrodynamic interaction would have consequences for the detection of "flavored eddies". Invertebrates often appear to have hard-wired sensory filters in their peripheral sensory systems. The results of this work may find application in the design of sensors and algorithms for automated odor plume tracing in such tasks as detection and localization of sources of chemical pollution, both under water and in air.