Neuromodulation plays a crucial role in facilitating research into brain function and enabling treatments for neurological and psychiatric disorders. In brain research, current non-invasive tools face challenges when studying brain sub-regions due to their limited spatial resolution, which can barely reach a scale of 100 μm. Moreover, precise control over the volume of tissue activated (VTA) is needed to effectively target diverse-shaped brain regions, such as ocular dominance columns. Similarly, in disease treatment, the lack of sufficient spatial resolution poses obstacles in restoring normal vision using existing FDA-approved retina prostheses for retinitis pigmentosa.
To address these challenges, my thesis work focuses on the development of optically-generated ultrasound devices for non-invasive brain stimulation and implantable retina prostheses. Firstly, to meet the need for non-invasive neuromodulation with ultrahigh precision, we have developed an optically-generated focused ultrasound device. By embedding candle soot nanoparticles in a curved polydimethylsiloxane pad, this device generates a transcranial ultrasound focus at 15 MHz with an ultrahigh lateral resolution of 83 μm. This resolution is two orders of magnitude smaller than conventional transcranial-focused ultrasound, enabling successful submillimeter transcranial stimulation in vivo targeting the mouse motor cortex.
Addressing the requirement for a customized VTA in specific brain sub-regions, we have developed an optically-generated Bessel beam ultrasound device. This device was specifically designed to target brain columns with an elongated acoustic focus, and it successfully achieved a VTA with a lateral resolution of 152 μm and an axial resolution of 1.93 mm. The stimulation capability of the device has been confirmed through immunofluorescence imaging, which showed that the stimulation depth in mouse brains reached up to 2.2 mm.
Furthermore, in order to address the need for an ultrahigh spatial resolution in retina prosthesis, we have developed an optically-generated ultrasound film as a subretinal prosthesis. In proof-of-concept experiments using blind rat retina, this film
has successfully achieved retina stimulation ex vivo.
In conclusion, optically-generated ultrasound devices offer promising opportunities for brain science research and disease treatments. They revolutionize non-invasive brain stimulation with ultrahigh precision and customized VTA for studying brain sub-regions. Additionally, they hold the potential for enhancing spatial resolution in retina prostheses, bringing hope to individuals with retinal disorders. / 2024-09-08T00:00:00Z
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/46706 |
| Date | 08 September 2023 |
| Creators | Li, Yueming |
| Contributors | Cheng, Ji-Xin |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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