# The electrode-neural interface in auditory brainstem implants

> **NIH NIH R21** · NEW YORK UNIVERSITY SCHOOL OF MEDICINE · 2022 · $254,250

## Abstract

PROJECT SUMMARY
Auditory brainstem implants (ABI) are the only therapeutic option for deaf patients with abnormal cochlea or
auditory nerve. ABIs bypass the auditory nerve and directly stimulate the central auditory pathways using
electrodes surgically placed on the cochlear nucleus. Current ABI devices use the same coding strategies as
cochlear implants (CI) to encode sound into electrical stimulation. However, despite identical external
hardware, signal processing, and stimulation patterns being delivered by ABI and CI electrodes, the two
devices have very different outcomes. Only a small percentage of ABI patients can understand speech using
their device, whereas CI patients can generally communicate verbally using their device alone. The
mechanisms for these disparate outcomes are elusive, but may be related to the differences in electrode-
neural interface characteristics between the two devices. The cochlear nucleus, the site of ABI stimulation, is
much more complex than the auditory nerve and consists of diverse neuron types. The majority of cochlear
nucleus neural types have different biophysical properties than the auditory nerve. Aim 1 is to study electrode-
neural interface characteristics in ABI patients and their relation to perceptual outcomes. We will study
electrode-neural interface by obtaining electrically-evoked compound action potentials (ECAPs) using the
voltage recording capability of the implant device. We will use ECAP to assess the morphology of neural
responses as well as neural recovery and adaptation of neural responses. We will also assess neural
interactions between different electrodes. We will evaluate the association between electrode-neural interface
and behavioral performance, and assess how this association differs between ABI and CI patients. Aim 2 is to
evaluate whether the electrode-neural interface measures can guide elimination of poorly functioning
electrodes to improve ABI patient outcomes. We will compare speech perception outcomes obtained before
and after eliminating the poorly functioning electrodes from the coding strategy. Speech perception outcomes
with each new manipulation will be measured when the subjects have had the opportunity to adapt to it for one
month. This study will provide critical understanding regarding auditory processing differences between ABI
and CI users, which may be related to differences in electrode-neural interface between the cochlea and the
cochlear nucleus.

## Key facts

- **NIH application ID:** 10432541
- **Project number:** 1R21DC020305-01
- **Recipient organization:** NEW YORK UNIVERSITY SCHOOL OF MEDICINE
- **Principal Investigator:** Mahan Azadpour
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $254,250
- **Award type:** 1
- **Project period:** 2022-05-01 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10432541

## Citation

> US National Institutes of Health, RePORTER application 10432541, The electrode-neural interface in auditory brainstem implants (1R21DC020305-01). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10432541. Licensed CC0.

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