Functionally redundant peg sensilla on the scorpion pecten

J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2011 Sep;197(9):895-902. doi: 10.1007/s00359-011-0650-9. Epub 2011 Jun 7.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Chemoreceptor Cells / drug effects
  • Chemoreceptor Cells / physiology*
  • Citric Acid / pharmacology
  • Ethanol / pharmacology
  • Female
  • Male
  • Pecten / drug effects
  • Pecten / physiology*
  • Potassium Chloride / pharmacology
  • Scorpions / drug effects
  • Scorpions / physiology*
  • Sense Organs / drug effects
  • Sense Organs / physiology*
  • Sensory Receptor Cells / drug effects
  • Sensory Receptor Cells / physiology
  • Sexual Behavior, Animal / drug effects
  • Sexual Behavior, Animal / physiology*
  • Species Specificity

Substances

  • Citric Acid
  • Ethanol
  • Potassium Chloride