Document Detail

Tuning to interaural time difference and frequency differs between the auditory arcopallium and the external nucleus of the inferior colliculus.
MedLine Citation:
PMID:  19261709     Owner:  NLM     Status:  MEDLINE    
Barn owls process sound-localization information in two parallel pathways, the midbrain and the forebrain pathway. Exctracellular recordings of neural responses to auditory stimuli from far advanced stations of these pathways, the auditory arcopallium in the forebrain and the external nucleus of the inferior colliculus in the midbrain, demonstrated that the representations of interaural time difference and frequency in the forebrain pathway differ from those in the midbrain pathway. Specifically, low-frequency representation was conserved in the forebrain pathway, while it was lost in the midbrain pathway. Variation of interaural time difference yielded symmetrical tuning curves in the midbrain pathway. By contrast, the typical forebrain-tuning curve was asymmetric with a steep slope crossing zero time difference and a less-steep slope toward larger contralateral time disparities. Low sound frequencies contributed sensitivity to contralateral leading sounds underlying these asymmetries, whereas high frequencies enhanced the steepness of slopes at small interaural time differences. Furthermore, the peaks of time-disparity tuning curves were wider in the forebrain than in the midbrain. The distribution of the steepest slopes of best interaural time differences in the auditory arcopallium, but not in the external nucleus of the inferior colliculus, was centered at zero time difference. The distribution observed in the auditory arocpallium is reminiscent of the situation observed in small mammals. We speculate that the forebrain representation may serve as a population code supporting fine discrimination of central interaural time differences and coarse indication of laterality of a stimulus for large interaural time differences.
Katrin Vonderschen; Hermann Wagner
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-03-04
Journal Detail:
Title:  Journal of neurophysiology     Volume:  101     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-04-21     Completed Date:  2009-06-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2348-61     Citation Subset:  IM    
Institute of Biology II, RWTH Aachen University, D-52074 Aachen, Germany.
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MeSH Terms
Acoustic Stimulation / methods
Action Potentials / physiology
Auditory Pathways / physiology
Auditory Perception / physiology*
Brain Mapping
Functional Laterality / physiology
Inferior Colliculi / cytology*,  physiology
Neurons / drug effects,  physiology*
Reaction Time / physiology
Sound Localization / physiology*
Time Perception / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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