Dynamic Current Steering Visual Prosthesis Phosphene Integration
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Solution Overview
Problem
Current visual cortical prosthetics (VCPs) fail to combine multiple phosphenes into coherent visual forms, resulting in patients perceiving disconnected points of light instead of unified visual forms, which is a setback for clinical trials aiming to restore vision in the blind.
Innovation Solution
The implementation of a novel stimulation paradigm called 'dynamic current steering,' which involves rapidly sweeping electrical stimulation across the retinotopic map in patterns corresponding to desired visual objects and concurrently stimulating nearby electrodes to produce activation at intermediate locations, effectively combining phosphenes into unified percepts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple electrodes are stimulated simultaneously to produce multiple phosphenes, then the visual information coverage is improved, but the phosphenes cannot be integrated into coherent visual forms and appear as disconnected points of light
Solution Approach 1:
The patent applies dynamic stimulation by sequentially activating electrodes in a time-varying pattern rather than simultaneous static activation. The stimulation follows continuous paths through the electrode array, creating moving phosphenes that trace out visual forms. This dynamic approach allows the visual system to integrate the sequence of phosphenes into coherent shapes, resolving the contradiction between producing multiple phosphenes and maintaining visual form coherence.
Solution Approach 2:
The patent pre-plans stimulation paths that trace the contours of desired visual forms before actual stimulation occurs. By mapping out continuous paths through the electrode array in advance and following these predetermined trajectories during stimulation, the system ensures that phosphenes will naturally coalesce into the intended visual forms, maintaining coherence while covering multiple visual information points.
2Measurement precision
If a high-resolution two-dimensional array of points is used to map the visual image, then the visual information detail is improved, but the electrode actuation complexity increases
Solution Approach 1:
The patent segments the high-resolution two-dimensional visual image into continuous one-dimensional paths that can be traced by sequential electrode stimulation. By decomposing the complex 2D image mapping problem into simpler path-following sequences, the system maintains high visual resolution while reducing the control complexity from managing simultaneous 2D electrode patterns to managing temporal sequences along 1D trajectories.
Solution Approach 2:
The patent transforms the two-dimensional spatial mapping problem into a one-dimensional temporal sequence problem. Instead of controlling electrode activation across a 2D array simultaneously, the system maps visual information onto continuous paths and activates electrodes sequentially along these paths, effectively adding a time dimension and reducing spatial complexity.
3Stability of the object's composition
If electrodes are actuated sequentially along continuous paths, then the integration of phosphenes into visual forms is improved, but the time required for image presentation increases
Solution Approach 1:
The patent maintains continuous useful action by ensuring that electrode stimulation follows unbroken continuous paths through the electrode array. This continuous stimulation approach allows the visual system to integrate phosphenes into coherent forms without interruption, maintaining visual form coherence while optimizing the time required for complete image presentation through efficient path traversal.
Solution Approach 2:
The patent optimizes the balance between visual form coherence and presentation time by adjusting stimulation parameters such as the speed of path traversal, the duration of each electrode activation, and the spacing between sequential stimulations. By carefully tuning these temporal parameters, the system achieves coherent visual form integration within an acceptable time frame.
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
Dynamic current steering significantly enhances the ability of VCPs to produce useful percepts of visual forms, allowing patients to describe and draw intended shapes with ease, as supported by preliminary data, and is predicted to significantly outperform existing stimulation paradigms in terms of accuracy and efficiency.
Implementation Method 1
All VCPs rely on electrical stimulation of visual cortex to produce percepts of spots of lights, known as phosphenes
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3E
AI summary
One aspect of the invention provides a computer-implemented method of conveying a visual image to a blind subject fitted with a visual prosthesis. The computer-implemented method includes: mapping a representation of a visual image onto a two-dimensional array of points having a resolution greater than or equal to an electrode resolution of the visual prosthesis; identifying one or more continuous paths along the mapped representation; and controlling the visual prosthesis to sequentially actuate electrodes along the one or more paths. Another aspect of the invention provides a system including: a visual prosthesis comprising multiple electrodes; and an imaging processing device in communication with the visual prosthesis. The imaging processing device can be programmed to receive an image and perform any of the methods described herein.