Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2014 Oct 1;8:116. doi: 10.3389/fncir.2014.00116

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2014 Grothe and Pecka.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

PMC Copyright notice

LSO and MSO responses are modulated by prior activity and thus encode relative sound-source positions. The firing rates of both LSO and MSO neurons are controlled in an activity-dependent manner via GABAergic inhibition. (A) In the LSO, GABA is released retrogradly by dendritic release from LSO neurons onto their synaptic partners. (B) In the MSO, GABA is released via a di-synaptic feedback loop including the SPN (superior para-olivary nucleus). Both mechanisms generate levels of GABA-mediated inhibition that are proportional to the prior activity of the respective LSO/MSO neuron. In both cases, the firing activity is modulated by GABA_B-receptors, resulting in a divisive gain control mechanism. Data modified from Magnusson et al. (2008) (A) and Stange et al. (2013) (B). (C) In vivo recordings in gerbils showed that upon prolonged presentation of an Adapter stimulus from a very lateralized sound-source position (stimulus paradigm is schematized in upper left), the GABAergic gain control results in asymmetric changes in the two coding channels (ipsi- and contralateral MSOs or LSOs) due to the asymmetric activity profile between the two channels and the activity dependence of the gain control mechanism. Particularly, the cross-point between left and right coding channel is shifted away from the actual midline (indicated by red horizontal arrows) and toward the location of the Adapter location (indicated by black vertical arrow). In accordance with the hypothesis of hemispheric coding channels of sound localization, this stimulation paradigm leads to systematic shifts of the perception of test tone positions in human listeners (right column). The result from a single subject is shown in the upper panel, the average from four subjects is shown in the lower panel. A difference score of 5 approximates a shift in lateral perception of 30°. As predicted from the activity-dependence of the GABAergic gain control circuit, the presentation of an Adapter stimulus at a different frequency than the test tone (green line) did not affect the localization percept. Data taken from Stange et al. (2013)