Document Detail

Synaptic mechanisms underlying interaural level difference selectivity in rat auditory cortex.
MedLine Citation:
PMID:  25185807     Owner:  NLM     Status:  Publisher    
The interaural level difference (ILD) is a sound localization cue that is extensively processed in the auditory brainstem and midbrain, and is also represented in the auditory cortex. Here we asked whether neurons in the auditory cortex passively inherit their ILD tuning from subcortical sources or whether their spiking preferences were actively shaped by local inhibition. If inherited, the ILD selectivity of spiking output should match that of excitatory synaptic input. If shaped by local inhibition, by contrast, excitation should be more broadly tuned than spiking output, with inhibition suppressing spiking for non-preferred stimuli. To distinguish between these two processing strategies, we compared spiking responses to excitation and inhibition in the same neurons across a range of ILDs and average binaural sound levels. We found that cells preferring contralateral ILDs (often called EI cells) followed the inheritance strategy. In contrast, cells that were unresponsive to monaural sounds but responded predominantly to near-zero ILDs (PB cells) instead showed evidence of the local processing strategy. These PB cells received excitatory inputs that were similar to those received by the EI cells. However, contralateral monaural sounds and ILDs greater than 0 dB elicited strong inhibition, quenching the spiking output. These results suggest that in the rat auditory cortex, EI cells do not utilize inhibition to shape ILD sensitivity, whereas PB cells do. We conclude that an auditory cortical circuit computes sensitivity for near-zero ILDs.
Michael Kyweriga; Whitney Stewart; Carolyn Cahill; Michael Wehr
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-9-3
Journal Detail:
Title:  Journal of neurophysiology     Volume:  -     ISSN:  1522-1598     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2014 Sep 
Date Detail:
Created Date:  2014-9-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2014, Journal of Neurophysiology.
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