Non-Invasive Brain-to-Brain Interface (BBI): Establishing Functional Links between Two Brains
Seung-Schik Yoo, Hyungmin Kim, Emmanuel Filandrianos, Seyed Javid Taghados, Shinsuk Park
PLoS ONE 2013, 8, e60410 · 10.1371/journal.pone.0060410
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.
Abstract via europepmc.
Exposures
Exposure 1: FUS excitation of rat tail motor cortex, triggered by a human SSVEP brain-computer interface
Target: motor cortex — “the area associated with tail movement”
Device: custom-built
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 350 | ✓✓✓ |
| Pulse duration (ms) | 0.5 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 50pulse duration × PRF gives 50% | ✓✓✓ |
| Sonication duration (s) | 0.3 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | deratingsingle value | |
| In-situ pressure (kPa) | 530 | ✓✓✓ |
| In-situ Isppa (W/cm²) | 8.6 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 4.3 | ✓✓✓ |
Two function generators were used to create the pulsed operation of sonication; the first generator controlled the overall duration of sonication (300 msec) and pulse repetition frequency (PRF: 1 KHz); the second generator, triggered by the first, generated a sinusoidal waveform at 350 kHz with a tone burst duration (TBD) of 0.5 msec. Sonication was triggered automatically by a computer upon detection of a human volunteer's steady-state visual evoked potential (SSVEP), and the circuit was disabled for 10 s after each trigger to prevent repetitive operation.
Flags from extraction
n_subjects— Text shows 'weight 363637 g' for the six rats, an apparent OCR/formatting artifact of a mean +/- SD value (likely 363 +/- 37 g); recorded here as it appears in the source.model_system— The study also involved 7 (optimization) and 6 (main BBI) human volunteers who performed the EEG/SSVEP brain-computer-interface task, but no ultrasound was ever applied to the humans; model_system and n_subjects therefore reflect only the sonicated rats.adverse_events— The paper only cites a previous study (Yoo et al. 2011) as having used similar parameters without biological damage; it does not report a specific safety observation for the animals in this study.