title: Toward Deep Brain Monitoring with Superficial EEG Sensors Plus Neuromodulatory Focused Ultrasound.
abstract: Noninvasive recordings of electrophysiological activity have limited anatomic specificity and depth. We hypothesized that spatially tagging a small volume of brain with a unique electroencephalography (EEG) signal induced by pulsed focused ultrasound could overcome those limitations. As a first step toward testing this hypothesis, we applied transcranial ultrasound (2 MHz, 200-ms pulses applied at 1050 Hz for 1 s at a spatial peak temporal average intensity of 1.4 W/cm(2)) to the brains of anesthetized rats while simultaneously recording EEG signals. We observed a significant 1050-Hz electrophysiological signal only when ultrasound was applied to a living brain. Moreover, amplitude demodulation of the EEG signal at 1050 Hz yielded measurement of gamma band (>30 Hz) brain activity consistent with direct measurements of that activity. These results represent preliminary support for use of pulsed focused ultrasound as a spatial tagging mechanism for non-invasive EEG-based mapping of deep brain activity with high spatial resolution.
authors.affiliation: Department of Neurosurgery, University of Washington, Seattle, Washington, USA.
authors.forename: Felix
authors.initials: F
authors.lastname: Darvas
authors.affiliation: Department of Neurosurgery, University of Washington, Seattle, Washington, USA.
authors.forename: Edin
authors.initials: E
authors.lastname: Mehić
authors.affiliation: Department of Bioengineering, University of Washington, Seattle, Washington, USA.
authors.forename: Connor J
authors.initials: CJ
authors.lastname: Caler
authors.affiliation: Department of Neurosurgery, University of Washington, Seattle, Washington, USA.
authors.forename: Jeff G
authors.initials: JG
authors.lastname: Ojemann
authors.affiliation: Department of Neurosurgery, University of Washington, Seattle, Washington, USA; Division of Engineering and Mathematics, University of Washington, Bothell, Washington, USA. Electronic address: doumitt@uw.edu.
authors.forename: Pierre D
authors.initials: PD
authors.lastname: Mourad
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D023421:Models, Animal; D019047:Phantoms, Imaging; D051381:Rats; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*
keywords: Brain activity; EEG; Focused ultrasound