Transcranial Focused Ultrasound for Selective Deep Brain Neuromodulation
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Solution Overview
Problem
Current neuromodulation techniques, such as transcranial magnetic stimulation and transcranial current stimulation, face challenges in achieving high spatial focus and deep penetration, while optogenetics is hindered by practical translation issues in human clinical utility due to its invasive methods.
Innovation Solution
The use of transcranial focused ultrasound (tFUS) with adjustable pulse repetition frequency and collimator-directed energy to selectively stimulate specific neuron populations, inducing long-term changes in synaptic connectivity without invasive methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If transcranial magnetic stimulation or transcranial current stimulation is used, then clinical translation is easier, but spatial focus and penetration depth are insufficient
Solution Approach 1:
The patent replaces electromagnetic stimulation methods (TMS, tACS) with mechanical ultrasound waves for brain stimulation. This substitution allows deep penetration through the skull with high spatial focus while remaining non-invasive and clinically translatable. The focused ultrasound waves mechanically stimulate specific neural circuits without the spatial resolution limitations of electromagnetic methods.
Solution Approach 2:
The patent utilizes parameter tuning of ultrasound characteristics (frequency, intensity, pulse duration, duty cycle) to achieve selective stimulation of different neuron types. By changing these parameters, the system can target specific neural populations with high precision while maintaining non-invasive clinical applicability.
2Manufacturing precision
If optogenetics is used, then cell-type selectivity is high, but invasive methods prevent human clinical utility
Solution Approach 1:
The patent replaces optical stimulation (optogenetics) with mechanical ultrasound stimulation. This substitution eliminates the need for invasive viral vector delivery and transgenic approaches, making the method suitable for human clinical applications while maintaining cell-type selectivity through parameter tuning of the ultrasound.
Solution Approach 2:
The patent uses ultrasound waves as an intermediary to achieve non-invasive cell-type selective stimulation. Instead of directly introducing genetic materials into neurons, the ultrasound acts as a mediator that can selectively stimulate specific neuron types through their inherent biophysical properties, avoiding the invasiveness of optogenetic approaches.
3Productivity
If conventional ultrasound parameters are used, then general neural stimulation is achieved, but selectivity for specific neuron subpopulations is insufficient
Solution Approach 1:
The patent achieves neuron subpopulation selectivity by systematically varying ultrasound parameters including frequency (20-100 MHz), intensity, pulse duration, and duty cycle. Different neuron types respond differently to these parameter variations, enabling selective stimulation of regular-spiking versus fast-spiking units and other specific subpopulations.
Solution Approach 2:
The patent employs dynamic adjustment of ultrasound parameters during stimulation to selectively target different neuron types. By modulating the ultrasound characteristics in real-time, the system can adaptively stimulate specific neural circuits while avoiding activation of other neuron populations, achieving high selectivity without invasive methods.
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
tFUS enables non-invasive, high spatial focality and deep penetration, effectively stimulating specific neuron types and inducing sustained neural effects, potentially offering a powerful tool for therapeutic applications like Alzheimer's treatment.
Implementation Method 1
a dynamic acoustic radiation force is induced by the tFUS at the ultrasound pulse repetition frequency
Data Source
AI summary
Specific parameter sets are provided that makes the transcranial focused ultrasound to selectively activate a certain neuronal type at cortical brain and enables the transcranial focused ultrasound to non-invasively induce long-term effects at deep brain. A type of ultrasound collimator with incidence angle control is designed and validated through acoustic field pressure mapping in order to target brain areas at different depths. Multi-elements transducer arrays are also used to achieve transmission of focused ultrasound.