Optical Fiber Neuromodulation System for Targeted Neuronal Stimulation
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Solution Overview
Problem
Electrode-based stimulation techniques for the brain are indiscriminate and face challenges due to the distributed nature of neurons, leading to issues with targeting specific cells and maintaining mechanical stability, which can result in unintended stimulation and reduced effectiveness over time.
Innovation Solution
A system using an elongated structure with a modulation circuit and optical fiber arrangement to deliver viral vectors for expressing light-responsive proteins in target cells, allowing for precise optical stimulation through light activation of ion channels like ChR2 and NpHR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrode-based stimulation is used to stimulate neurons, then electrical signals can be delivered to target cells, but the stimulation becomes indiscriminate and activates unintended neurons due to the distributed nature of neurons and physical proximity requirements
Solution Approach 1:
The patent replaces the mechanical/electrical electrode-based stimulation system with an optical stimulation system. Light-responsive proteins (opsins) are expressed in target neurons, and optical fibers deliver light to these proteins to induce neuronal activation. This substitution eliminates the need for direct physical contact with neurons, allowing precise spatial targeting through optical fiber placement while avoiding indiscriminate activation of surrounding neurons that occurs with electrode-based methods.
Solution Approach 2:
The patent introduces local quality by making only specific target neurons responsive to light through selective expression of light-responsive proteins in those neurons. This genetic targeting ensures that when light is delivered via optical fiber, only the neurons expressing the opsin proteins are activated, while surrounding neurons remain unaffected. This creates a localized response exactly where needed, resolving the indiscriminate nature of electrode stimulation.
2Reliability
If electrode placement is used for brain stimulation, then specific neurons can be targeted, but mechanical stability deteriorates over time leading to lead migration and reduced stimulation effectiveness
Solution Approach 1:
The patent replaces the mechanical electrode leads that physically contact brain tissue with an optical fiber system. Optical fibers are mechanically more stable and less prone to migration than flexible electrode leads. The fibers can be securely anchored and maintain their position better over time, ensuring consistent light delivery to the target neurons and maintaining stimulation effectiveness without the lead migration problems that plague electrode-based systems.
3Reliability
If electrical resistance of electrodes increases due to glial cell encapsulation, then higher voltage or frequency is required to achieve stimulation, but this spreads electrical current and activates additional unintended cells
Solution Approach 1:
The patent replaces electrical stimulation with optical stimulation. Light delivery through optical fibers does not suffer from increasing resistance due to glial encapsulation. The optical system maintains consistent light delivery to target neurons over time, and the spatial confinement of light prevents the spread effect that occurs when electrical parameters are increased to overcome resistance. This resolves both the threshold maintenance problem and the unintended activation problem simultaneously.
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
Enables precise and controlled stimulation of target cells with reduced unintended activation, maintaining effectiveness over time by using light-responsive proteins to modulate neuronal activity.
Implementation Method 1
light activated proteins can be used to control the flow of ions through cell membranes. Ion channels and ion pumps are cell-membrane proteins that control the transport of positively or negatively charged ions (e.g., sodium, potassium and chloride) across the cell membrane
Data Source
AI summary
In one example, a system electrically stimulates target cells of a living animal using an elongated structure, a modulation circuit and a light pathway such as provided by an optical fiber arrangement. The elongated structure is for insertion into a narrow passageway in the animal such that an end of the elongated structure is sufficiently near the target cells to deliver stimulation thereto. The modulation circuit is for modulating the target cells while the elongated structure is in the narrow passageway, where the modulation circuit is adapted to deliver viral vectors through the elongated structure for expressing light responsive proteins in the target cells. The light pathway is used for stimulating the target cells by delivering light to the light-responsive proteins in the target cells.