Document Detail

Temporal coding mediates discrimination of "bitter" taste stimuli by an insect.
MedLine Citation:
PMID:  16943545     Owner:  NLM     Status:  MEDLINE    
The mechanisms that mediate discriminative taste processing in insects are poorly understood. We asked whether temporal patterns of discharge from the peripheral taste system of an insect (Manduca sexta caterpillars; Sphingidae) contribute to the discrimination of three "bitter" taste stimuli: salicin, caffeine, and aristolochic acid. The gustatory response to these stimuli is mediated exclusively by three pairs of bitter-sensitive taste cell, which are located in the medial, lateral, and epipharyngeal sensilla. We tested for discrimination by habituating the caterpillars to salicin and then determining whether the habituation generalized to caffeine or aristolochic acid. We ran habituation-generalization tests in caterpillars with their full complement of taste sensilla (i.e., intact) and in caterpillars with ablated lateral sensilla (i.e., lat-ablated). The latter perturbation enabled us to examine discrimination in caterpillars with a modified peripheral taste profile. We found that the intact and lat-ablated caterpillars both generalized the salicin-habituation to caffeine but not aristolochic acid. Next, we determined whether this pattern of stimulus-generalization could be explained by salicin and aristolochic acid generating distinct ensemble, rate, temporal, or spatiotemporal codes. To this end, we recorded excitatory responses from the bitter-sensitive taste cells and then used these responses to formulate predictions about whether the salicin-habituation should generalize to caffeine or aristolochic acid, separately for each coding framework. We found that the pattern of stimulus generalization in both intact and lat-ablated caterpillars could only be predicted by temporal coding. We conclude that temporal codes from the periphery can mediate discriminative taste processing.
John I Glendinning; Adrienne Davis; Meelu Rai
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  26     ISSN:  1529-2401     ISO Abbreviation:  J. Neurosci.     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-08-31     Completed Date:  2006-09-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8900-8     Citation Subset:  IM    
Department of Biological Sciences, Barnard College, Columbia University, New York, New York 10027, USA.
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MeSH Terms
Aristolochic Acids / pharmacology
Benzyl Alcohols / pharmacology
Caffeine / pharmacology
Discrimination (Psychology) / physiology*
Generalization (Psychology)
Habituation, Psychophysiologic
Manduca / physiology*
Neurons, Afferent / drug effects,  physiology
Taste / physiology*
Time Factors
Grant Support
Reg. No./Substance:
0/Aristolochic Acids; 0/Benzyl Alcohols; 138-52-3/salicin; 313-67-7/aristolochic acid I; 58-08-2/Caffeine

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