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Stereotactically-guided Ablation of the Rat Auditory Cortex, and Localization of the Lesion in the Brain
Published on: October 11, 2017
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Stimulus dependence of contralateral dominance in human auditory cortex
Alexander Gutschalk1, Iris Steinmann
1Department of Neurology, Universität Heidelberg, 69120, Heidelberg, Germany.
Human Brain Mapping
|October 28, 2014
Summary
Auditory system responses to sound show stimulus-dependent contralateral dominance. Blood oxygen level dependent (BOLD) and magnetoencephalography (MEG) findings reveal bilateral activity in auditory cortex (AC) for amplitude modulation, challenging previous assumptions.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Human Brain Imaging
Background:
- The auditory system's contralateral dominance is debated, with varying physiological reports.
- Previous studies show inconsistent contralateral dominance for monaural sound stimulation.
Purpose of the Study:
- To investigate stimulus-dependent contralateral dominance in the auditory system.
- To differentiate auditory cortex (AC) activity related to sound modulation versus steady-state responses.
Main Methods:
- Used blood oxygen level dependent (BOLD) fMRI and magnetoencephalography (MEG) with unmodulated (UN) and amplitude-modulated (AM) noise.
- Analyzed responses in contralateral and ipsilateral auditory cortex (AC) and subcortical structures like the superior olivary complex (SOC).
- Included an acallosal participant to assess the role of transcallosal pathways.
Main Results:
- BOLD responses to UN showed contralateral AC activation and ipsilateral deactivation.
- AM noise evoked stronger contralateral AC activation with minimal ipsilateral activation.
- Difference imaging (AM vs. UN) revealed bilateral AC activation, stronger contralaterally.
- MEG showed steady-state activity phase-locked to AM, lacking consistent contralateral dominance.
- Subcortical BOLD activation post-SOC was strongly contralateral and similar for AM and UN.
- Acallosal participant data ruled out transcallosal transmission as a cause for ipsilateral effects.
Conclusions:
- Ascending auditory activity post-SOC is strongly contralateral.
- Auditory cortex (AC) activity related to slow amplitude modulation is more bilateral.
- Ipsilateral deactivation can influence measures of contralateral BOLD dominance.
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