Transcranial Focused Ultrasound Enhances the Discriminative Power of Targeted Voluntary Motor Signals in Humans
Joshua Kosnoff, Joseph Zhang, Yisha Zhang, Yidan Ding, Zach Johnson, Bin He
IEEE Transactions on Neural Systems and Rehabilitation Engineering 2026 · 10.1109/tnsre.2026.3720609
Abstract
Transcranial focused ultrasound (tFUS) is an emerging neuromodulation technique with high spatial specificity and deep brain penetration, but its effects on upper-limb voluntary motor signals relevant to brain-computer interfaces (BCIs) remain unknown. In this study, we investigated whether tFUS targeted at the motor cortex can enhance movement-related cortical potentials (MRCPs) and improve the discriminability of hand grasp signals. Eighteen healthy participants performed visually-cued left and right hand grasps while EEG and EMG were recorded during three condition types: left motor cortex-targeted tFUS, right prefrontal cortex-targeted tFUS, and a non-modulated baseline. Ultrasound pulse trains were delivered time-locked to movement cues using pulse repetition frequencies (PRFs) of 30 and 3000 Hz and duty cycles of 30% and 60%. Left motor cortex-targeted tFUS significantly amplified both MRCP amplitude and signal discriminability for BCI classification relative to both spatial sham and non-modulated conditions. Neither MRCP amplification nor BCI classification accuracy were found to change with the investigated PRFs or duty cycles. These findings demonstrate that tFUS can selectively enhance voluntary motor cortical signals and improve motor EEG-based BCI performance.
Abstract via europepmc.
Exposures
Exposure 1: Left primary motor cortex hand knob (LM1), 4 PRF x DC parameter sets
Target: primary motor cortex — “hand knob of the left primary motor cortex (LM1)”
Device: Blatek · Blatek Industries Inc., Boalsburg, PA, USA · single-element focused transducer (1.5 inch focal length, 1 inch aperture diameter, 0.75 inch radius of curvature) ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not reported | ⚑ |
| Pulse repetition frequency (Hz) | 30, 3,000swept | ✓✓✓ |
| Duty cycle (%) | 30, 60swept | ✓✓✓ |
| Sonication duration (s) | 0.5 | ✓✓✓ |
| Free-field pressure (kPa) | 672 | ✓✓✓⚑ |
|---|---|---|
| Free-field Isppa (W/cm²) | 3.63 | ✓✓✓ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | simulationmean or range across subjects | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 0.05, 0.278swept | ✓✓✓⚑ |
| In-situ Ispta (W/cm²) | not reported |
A single 500 ms pulse train was delivered time-locked to the visual cue on every trial (70 trials per block, ~5 s fixation between). Cycles per pulse, PRF and pulse number varied to keep Isppa and sonication duration constant; PRF 30 or 3000 Hz crossed with DC 30% or 60%. Controls: non-modulated baseline (transducer off) and two rPFC shams at 30 Hz/30% and 3000 Hz/30%.
Consistency checks: intensity pressure inconsistent free field.
Flags from extraction
exposures[0].free_field.pressure_kpa— Stated as free water peak-to-peak pressure (672 kPa), not peak rarefactional.exposures[0].in_situ.isppa_w_cm2— Per-subject simulated transcranial Isppa from Table I (0.050 to 0.278 W/cm2); range taken from the table, no mean stated.exposures[0].timing.pulse_duration_ms— Pulse duration not stated; cycles per pulse varied with PRF and DC, so not computed.exposures[0].timing.waveform— Single 500 ms pulse train made of pulses at the stated PRF; the rPFC shams were real ultrasound at a different site and are described under sham_type, not as exposures.n_sessions_per_subject— Study has an MRI session and one tFUS-EEG session; not recorded as a number.