ORCID

Abstract

Tonotopy is a fundamental feature of auditory cortical organization, yet its influence on cortical auditory-evoked responses (AERs) remains unclear. Consequently, key properties of cortical AERs—such as their marked amplitude reduction with increasing stimulus frequency—still lack a coherent mechanistic explanation. To address this gap, we combined a meta-analysis of frequency-specific AER amplitudes with forward simulations of AERs informed by current knowledge of auditory cortical tonotopic layout and functional organization. The meta-analysis used a semi-systematic search covering all known automatic cortical AER components—both transient-evoked and steady-state—along with selected subcortical components for comparison. Forward simulations were based on a functional parcellation of the human supratemporal auditory region into subdivisions forming distinct tonotopic maps, and an idealized model of each division's intrinsic tonotopic layout. Parcellation was achieved using a novel, largely automated procedure applied to high-field (3 T) and ultra-high-field (7 T) functional and microstructural MRI mapping data from 30 individual hemispheres. Meta-analytic results revealed that, whilst all cortical AER components consistently show frequency-related amplitude reduction, reduction is greater in steady-state compared to transient-evoked components. Simulations indicated that frequency-related amplitude reduction arising from cortical morphology is confined to the highly myelinated central portion of Heschl's gyrus, suggesting that differences in reduction amount between steady-state and transient-evoked components may reflect differences in the relative strengths of their primary contributions. Our findings provide a new perspective on cortical AER generation. They represent an important step toward explaining morphology-related variability in AER amplitudes and establishing a quantitative link to underlying source strengths.

Publication Date

2026-08-04

Publication Title

Trends in Hearing

Volume

30

Acceptance Date

2026-05-12

Deposit Date

2026-08-14

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Medical Research Council (Grant Numbers G0901321, MC_UU_00010/2, MR/S003320/1) and the NIHR Nottingham Biomedical Research Centre.

Keywords

cortical auditory-evoked potentials/fields, EEG forward modeling, fMRI–EEG fusion, functional parcellation, intra-cortical myelination, tonotopic mapping, Evoked Potentials, Auditory/physiology, Acoustic Stimulation, Brain Mapping/methods, Humans, Auditory Pathways/physiology, Auditory Cortex/physiology, Magnetic Resonance Imaging, Computer Simulation, Models, Neurological, Auditory Perception

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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