Functionally redundant peg sensilla on the scorpion pecten

• Published in: Journal of Comparative Physiology 2011-09, Vol.197 (9), p.895-902
• Main Authors: Knowlton, Elizabeth D, Gaffin, Douglas D
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Animal Physiology; Animals; Biomedical and Life Sciences; Chemoreceptor Cells - drug effects; Chemoreceptor Cells - physiology; citric acid; Citric Acid - pharmacology; ethanol; Ethanol - pharmacology; Female; humans; Life Sciences; Male; moths; Neurosciences; Original Paper; Pecten - drug effects; Pecten - physiology; potassium chloride; Potassium Chloride - pharmacology; Scorpiones; Scorpions - drug effects; Scorpions - physiology; Sense Organs - drug effects; Sense Organs - physiology; sensilla; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - physiology; Sexual Behavior, Animal - drug effects; Sexual Behavior, Animal - physiology; Species Specificity; Zoology
• ISSN: 0340-7594; 1432-1351
• DOI: 10.1007/s00359-011-0650-9

All scorpions have two mid-ventral organs called pectines. Each pecten has thousands of pore-tipped sensilla sensitive to a variety of volatile organic and water-based stimulants. However, it was previously unknown whether individual sensilla were functionally identical or different. The information enhancement hypothesis predicts that all sensilla have similar chemosensitivities such that each is a unit of a parallel processing system. The information segmentation hypothesis states that sensilla differ in their chemosensitivities, a functional arrangement akin to the glomeruli-specific chemical detection system in the moth or human olfactory sense. In this study, we tested these hypotheses by extracellularly tip-recording sensillar responses to three aqueous tastants: 0.01 M KCl, 0.1 M citric acid, and 40% ethanol by volume. We isolated stimulation to one sensillum at a time and compared the chemoresponses. Sensilla appeared to respond similarly to the same stimulant (i.e., sensillar tip-recordings revealed activity of the same cell types), although sometimes a few sensilla responded with higher spike rates than the others. We conclude that our data primarily support the information enhancement hypothesis but for future tests of sensillar function we suggest a new hybrid model, which proposes that a few specialized sensilla exist among a mostly uniform field of identical sensilla.