Search
Presentation Details
| Poster #260 Odor-specific increases in both sensitivity and dynamic range in the olfactory bulb of the Mexican cavefish |
| Evan Lloyd & Douglas A. Storace Florida State University, Tallahassee, FL, United States |
Astyanax mexicanus, the Mexican tetra, consists of eyed, river dwelling surface populations (surface fish) and multiple eyeless cave populations (cavefish) which have undergone rapid sensory evolution, and therefore provide a unique comparative model by which to understand evolutionary processes. The sensory adaptations of the cavefish include eye loss, along with an expansion of the sensory organs and associated brain areas governing taste and smell. Previous studies have demonstrated that cavefish exhibit enhanced behavioral sensitivity to amino acids relative to their surface counterparts. However, the brain areas involved in this altered sensory perception are unknown. We tested the hypothesis that chemosensory adaptation in cavefish is the result of altered functional processing at the first stages of olfactory sensory processing, the epithelia and the bulb. We performed epifluorescence imaging in the olfactory bulbs of transgenic surface and cavefish that express the genetically encoded calcium indicator GCaMP6s in response to select amino acids presented at different concentrations. The functional response threshold of cavefish was 4 orders of magnitude lower in response to the odors alanine and lysine than age-matched surface fish. Other amino acids tested did not elicit differences in response between surface and cavefish. Our results suggest that cavefish sensory adaptations include changes in olfactory sensory processing beginning in the olfactory bulb. Future studies will examine the molecular changes mediating enhanced sensitivity, and behavioral outcomes of this adaptation. |