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Description
The auditory brainstem response (ABR) provides a non-invasive measure of synchronous neural activity along the ascending auditory pathway and is widely used in auditory neuroscience. Alterations in the ABR waveform serve as biomarkers of altered neural processing and can provide insight into the mechanisms of auditory disorders, including tinnitus. In this work, we present the first steps towards a biophysically grounded dipole model of ABR generators, linking neuronal population activity to scalp-recorded responses. Acoustic inputs are transformed into inner hair cell receptor potentials via the biophysical auditory periphery model of Verhulst et al. (2018). The IHC – auditory nerve fibre ribbon synapse is modelled as a calcium-dependent release process. Fibre-type heterogeneity (high-, medium-, and low-spontaneous rate fibres) is implemented through differences in calcium conductance and release threshold, allowing the model to capture the diversity of auditory nerve responses. The resulting postsynaptic currents drive a population of spiral ganglion cells (SGCs) implemented in a NetPyNE/NEURON framework. The SGC model incorporates Hodgkin–Huxley-type ion channel kinetics and multicompartmental morphologies, capturing key features of auditory nerve encoding, including high temporal precision and broad dynamic range. In response to a click stimulus, the model produces highly synchronous firing across the SGC population, giving rise to a macroscopic population dipole. A head volume conductor model subsequently maps this dipole to scalp-recorded electroencephalography (EEG) signals, corresponding to ABR wave I. To validate the physiological accuracy of the model, simulations of both SGC rate-intensity curves and ABR wave I latencies will be compared to experimental data.