title: Functionally redundant peg sensilla on the scorpion pecten.
abstract: 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.
authors.affiliation: Department of Zoology, University of Oklahoma, Norman, OK 73019-0235, USA. eknowlton@ou.edu
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Knowlton
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Gaffin
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D019343:Citric Acid / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D008297:Male; D049910:Pecten / Q000187:drug effects / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D012605:Scorpions / Q000187:drug effects / Q000502:physiology*; D012679:Sense Organs / Q000187:drug effects / Q000502:physiology*; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D013045:Species Specificity
chemical_list: D019343:Citric Acid; D000431:Ethanol; D011189:Potassium Chloride