Non-invasive transmission of sensorimotor information in humans using an EEG/focused ultrasound brain-to-brain interface
Wonhye Lee, Suji Kim, Byeongnam Kim, Chungki Lee, Yong An Chung, Laehyun Kim, Seung-Schik Yoo
PLOS ONE 2017, 12, e0178476 · 10.1371/journal.pone.0178476
Abstract
We present non-invasive means that detect unilateral hand motor brain activity from one individual and subsequently stimulate the somatosensory area of another individual, thus, enabling the remote hemispheric link between each brain hemisphere in humans. Healthy participants were paired as a sender and a receiver. A sender performed a motor imagery task of either right or left hand, and associated changes in the electroencephalogram (EEG) mu rhythm (8-10 Hz) originating from either hemisphere were programmed to move a computer cursor to a target that appeared in either left or right of the computer screen. When the cursor reaches its target, the outcome was transmitted to another computer over the internet, and actuated the focused ultrasound (FUS) devices that selectively and non-invasively stimulated either the right or left hand somatosensory area of the receiver. Small FUS transducers effectively allowed for the independent administration of stimulatory ultrasonic waves to somatosensory areas. The stimulation elicited unilateral tactile sensation of the hand from the receiver, thus establishing the hemispheric brain-to-brain interface (BBI). Although there was a degree of variability in task accuracy, six pairs of volunteers performed the BBI task in high accuracy, transferring approximately eight commands per minute. Linkage between the hemispheric brain activities among individuals suggests the possibility for expansion of the information bandwidth in the context of BBI.
Abstract via europepmc.
Exposures
Exposure 1: FUS stimulation of left/right hand primary somatosensory cortex (SI) for CBI
Target: primary somatosensory cortex — “left/right hand somatosensory area (SI); local maximum of the activated area posterior to the central sulcus within the postcentral gyrus”
Device: Ultran · Ultran, PA
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 210 | ✓✓✓ |
| Pulse duration (ms) | 1 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 500 | ✓✓✓ |
| Duty cycle (%) | 50pulse duration × PRF gives 50% | ✓✓✓ |
| Sonication duration (s) | 0.5 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 35 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 17.5 | ✓✓✓ |
| In-situ estimate | deratingmean or range across subjects | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | 3.5, 4.4swept | ✓✓✓ |
FUS actuations were triggered by the transmitted signal from the BCI segment (SD = 500 ms; ISI, inter-stimulation-interval, = 7 s; TBD = 1 ms; PRF = 500 Hz; Isppa = 35.0 W/cm2, per Fig 3B). Prior to the BBI session, FUS sonication (< 50 times) was administered to each side of the SI to confirm elicitation of tactile sensation before proceeding; subjects reported hand tactile sensation by pressing thumb against index finger.
Flags from extraction
exposures[0].in_situ.reported_as— The in-situ Ispta range (3.5-4.4 W/cm2) reflects uncertainty in the assumed acoustic transmission rate (20-25%) through the skull, not variability across subjects; 'mean_or_range_across_subjects' is used as the closest available vocabulary term.auditory_control— The paper discusses (in Discussion) that 2 of 6 subjects reported hearing a 'beeping' sound on the side opposite the sonication, and speculates this may relate to higher Isppa than prior studies, but no explicit auditory-masking or other control procedure is described as having been implemented.randomised— This is a single-arm CBI demonstration (no sham/control condition or randomised group allocation); only the left/right target order in the sender's BCI task was randomised.