title: Increased anatomical specificity of neuromodulation via modulated focused ultrasound.
abstract: Transcranial ultrasound can alter brain function transiently and nondestructively, offering a new tool to study brain function now and inform future therapies. Previous research on neuromodulation implemented pulsed low-frequency (250-700 kHz) ultrasound with spatial peak temporal average intensities (ISPTA) of 0.1-10 W/cm(2). That work used transducers that either insonified relatively large volumes of mouse brain (several mL) with relatively low-frequency ultrasound and produced bilateral motor responses, or relatively small volumes of brain (on the order of 0.06 mL) with relatively high-frequency ultrasound that produced unilateral motor responses. This study seeks to increase anatomical specificity to neuromodulation with modulated focused ultrasound (mFU). Here, 'modulated' means modifying a focused 2-MHz carrier signal dynamically with a 500-kHz signal as in vibro-acoustography, thereby creating a low-frequency but small volume (approximately 0.015 mL) source of neuromodulation. Application of transcranial mFU to lightly anesthetized mice produced various motor movements with high spatial selectivity (on the order of 1 mm) that scaled with the temporal average ultrasound intensity. Alone, mFU and focused ultrasound (FUS) each induced motor activity, including unilateral motions, though anatomical location and type of motion varied. Future work should include larger animal models to determine the relative efficacy of mFU versus FUS. Other studies should determine the biophysical processes through which they act. Also of interest is exploration of the potential research and clinical applications for targeted, transcranial neuromodulation created by modulated focused ultrasound, especially mFU's ability to produce compact sources of ultrasound at the very low frequencies (10-100s of Hertz) that are commensurate with the natural frequencies of the brain.
authors: Department of Bioengineering, University of Washington, Seattle, Washington, United States of America.
authors: Edin
authors: E
authors: Mehić
authors: Department of Materials Science and Engineering, University of Washington, Seattle, Washington, United States of America.
authors: Julia M
authors: JM
authors: Xu
authors: Department of Bioengineering, University of Washington, Seattle, Washington, United States of America.
authors: Connor J
authors: CJ
authors: Caler
authors: Department of Bioengineering, University of Washington, Seattle, Washington, United States of America.
authors: Nathaniel K
authors: NK
authors: Coulson
authors: Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, United States of America ; Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America.
authors: Chet T
authors: CT
authors: Moritz
authors: Department of Bioengineering, University of Washington, Seattle, Washington, United States of America ; Applied Physics Laboratory, University of Washington, Seattle, Washington, United States of America ; Department of Neurological Surgery, University of Washington, Seattle, Washington, United States of America ; Department of Engineering and Mathematics, University of Washington, Bothell, Washington, United States of America.
authors: Pierre D
authors: PD
authors: Mourad
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D008297:Male; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000502:physiology; D011312:Pressure; D014465:Ultrasonics / Q000295:instrumentation / Q000379:methods*