Cochlear Implant Channel Weighting for Focused Neural Stimulation
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Solution Overview
Problem
Traditional cochlear implants using monopolar stimulation struggle to focally stimulate small populations of spiral ganglion cells due to current spread along the cochlea, resulting in broad neural excitation patterns, and attempts to improve focus through multiple electrode channel configurations lead to nonlinear interactions and channel interactions.
Innovation Solution
A method and apparatus for determining weights for stimulation channels in a cochlear implant by computing a transadmittance matrix, adjusting the diagonal to minimize errors, and calculating weights to provide focused stimulation, allowing for more precise neural excitation patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If monopolar stimulation is used in traditional cochlear implants, then current spreads longitudinally along the cochlea, but this results in broad neural excitation patterns and inability to focally stimulate small subpopulations of spiral ganglion cells
Solution Approach 1:
The cochlear implant system divides the stimulation task into multiple independent bipolar channels, each capable of focal stimulation. The electrode array is segmented into multiple contact points that can be independently activated, allowing precise targeting of specific cochlear regions without current spread to distant areas.
Solution Approach 2:
Each bipolar channel is configured with local return paths that concentrate current flow in specific cochlear regions. The impedance values are measured and adjusted locally for each channel to optimize current distribution, ensuring that stimulation is confined to the intended target population of spiral ganglion cells.
2Measurement precision
If multiple channels are stimulated simultaneously with the same polarity to improve focus, then neural stimulation patterns combine, but electric fields accumulate and nonlinear channel interactions occur
Solution Approach 1:
The system employs interleaved stimulation patterns where multiple channels are activated in alternating time slots rather than simultaneously. This periodic activation sequence allows each channel to complete its stimulation cycle before the next channel begins, preventing electric field accumulation and nonlinear interactions while maintaining temporal resolution.
Solution Approach 2:
The stimulation system dynamically adjusts the activation sequence and timing of different channels based on real-time impedance measurements and channel interaction assessments. The interleaved pattern can be modified to optimize focus and minimize interactions, making the stimulation strategy adaptive rather than static.
3Object-generated harmful factors
If sequential or temporally interleaved stimulation patterns are used to avoid channel interactions, then adverse effects of monopolar channel configurations are reduced, but stimulation rates and spectral resolution are limited
Solution Approach 1:
The cochlear implant divides the auditory spectrum into multiple frequency channels, each mapped to specific electrode contacts. This segmentation allows simultaneous or interleaved stimulation of multiple frequency channels with bipolar configurations, increasing spectral resolution while maintaining focus through local current paths.
Solution Approach 2:
The interleaved stimulation pattern is designed to provide continuous useful action by rapidly alternating between channels within the temporal resolution of the auditory system. This creates the perceptual effect of simultaneous multi-channel stimulation while actually using sequential activation to avoid interactions, thereby increasing effective stimulation rates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables more focused neural excitation patterns and reduces channel interactions, allowing for simultaneous stimulation of multiple channels with improved spectral resolution and increased stimulation rates.
Implementation Method 1
determining a transimpendance matrix for the plurality of electrodes; computing a transadmittance matrix for the plurality of electrodes, the transadmittance matrix being a matrix inversion of the transimpendance matrix
Data Source
AI summary
Aspects are generally directed to techniques for determining weights for stimulation channels of a stimulating hearing prosthesis. The determined weights are used to provide stimulation to a recipient of the stimulating hearing prosthesis.