title: Non-invasive brain-to-brain interface (BBI): establishing functional links between two brains.
abstract: Transcranial focused ultrasound (FUS) is capable of modulating the neural activity of specific brain regions, with a potential role as a non-invasive computer-to-brain interface (CBI). In conjunction with the use of brain-to-computer interface (BCI) techniques that translate brain function to generate computer commands, we investigated the feasibility of using the FUS-based CBI to non-invasively establish a functional link between the brains of different species (i.e. human and Sprague-Dawley rat), thus creating a brain-to-brain interface (BBI). The implementation was aimed to non-invasively translate the human volunteer's intention to stimulate a rat's brain motor area that is responsible for the tail movement. The volunteer initiated the intention by looking at a strobe light flicker on a computer display, and the degree of synchronization in the electroencephalographic steady-state-visual-evoked-potentials (SSVEP) with respect to the strobe frequency was analyzed using a computer. Increased signal amplitude in the SSVEP, indicating the volunteer's intention, triggered the delivery of a burst-mode FUS (350 kHz ultrasound frequency, tone burst duration of 0.5 ms, pulse repetition frequency of 1 kHz, given for 300 msec duration) to excite the motor area of an anesthetized rat transcranially. The successful excitation subsequently elicited the tail movement, which was detected by a motion sensor. The interface was achieved at 94.0±3.0% accuracy, with a time delay of 1.59±1.07 sec from the thought-initiation to the creation of the tail movement. Our results demonstrate the feasibility of a computer-mediated BBI that links central neural functions between two biological entities, which may confer unexplored opportunities in the study of neuroscience with potential implications for therapeutic applications.
authors.affiliation: Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America. yoo@bwh.harvard.edu
authors.forename: Seung-Schik
authors.initials: SS
authors.lastname: Yoo
authors.forename: Hyungmin
authors.initials: H
authors.lastname: Kim
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Filandrianos
authors.forename: Seyed Javid
authors.initials: SJ
authors.lastname: Taghados
authors.forename: Shinsuk
authors.initials: S
authors.lastname: Park
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001921:Brain / Q000502:physiology; D062207:Brain-Computer Interfaces; D055724:Electrophysiological Phenomena; D005074:Evoked Potentials, Visual; D006801:Humans; D009043:Motor Activity; D010775:Photic Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013016:Sound; D013623:Tail / Q000502:physiology; D014159:Transducers