Transcranial Focused Ultrasound for Noninvasive Neuromodulation of the Visual Cortex

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 68; no. 1; pp. 21 - 28
• Main Authors: Lu, Gengxi, Qian, Xuejun, Castillo, Johnny, Li, Runze, Jiang, Laiming, Lu, Haotian, Kirk Shung, K., Humayun, Mark S., Thomas, Biju B., Zhou, Qifa
• Format: Journal Article
• Language: English
• Published: United States IEEE 01-01-2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustics; Animals; Artificial vision; Blindness; Cortical visual prosthesis; Electrodes; genetically blind rats; Humans; Neural prostheses; Prostheses; Pulse repetition frequency; Rats; Retina; Sound waves; Stimulation; transcranial focused ultrasound (tFUS); Transducers; Ultrasonic imaging; Ultrasonic Waves; Ultrasonography; Ultrasound; ultrasound stimulation; visual cortex (VC); Visual Cortex - diagnostic imaging; Visualization; Waveforms; United States > US
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2020.3005670

Currently, blindness cannot be cured and patients' living quality can be compromised severely. Ultrasonic (US) neuromodulation is a promising technology for the development of noninvasive cortical visual prosthesis. We investigated the feasibility of transcranial focused ultrasound (tFUS) for noninvasive stimulation of the visual cortex (VC) to develop improved visual prosthesis. tFUS was used to successfully evoke neural activities in the VC of both normal and retinal degenerate (RD) blind rats. Our results showed that blind rats showed more robust responses to ultrasound stimulation when compared with normal rats. (p <; 0.001, two-sample t-test). Three different types of ultrasound waveforms were used in the three experimental groups. Different types of cortical activities were observed when different US waveforms were used. In all rats, when stimulated with continuous ultrasound waves, only short-duration responses were observed at "US on and off" time points. In comparison, pulsed waves (PWs) evoked longer low-frequency responses. Testing different parameters of PWs showed that a pulse repetition frequency higher than 100 Hz is required to obtain the low-frequency responses. Based on the observed cortical activities, we inferred that acoustic radiation force (ARF) is the predominant physical mechanism of ultrasound neuromodulation.