Interactive effect between transcranial focused ultrasound and transcranial magnetic stimulation on human motor cortex
Kai-Hsiang Stanley Chen, Yih-Chih Jacinta Kuo, Chang-Yu Cheng, Yan-Siou Dong, Anton Fomenko, Jean-François Nankoo, Yi-Ping Liu, Robert Chen
Clinical Neurophysiology 2024, 167, 92-105 · 10.1016/j.clinph.2024.09.001
Abstract
Objective Transcranial focused ultrasound (TUS) can suppress human motor cortical excitability. However, it is unclear whether the TUS may interact with transcranial magnetic stimulation (TMS) when they co-delivered in multiple trials. Methods Nineteen subjects received three different TUS-TMS co-stimulation protocols to the motor cortex including concurrent stimulation (TUS-TMS-C), separated stimulation (TUS-TMS-S), and TMS only. In each condition, two runs of 30 stimulation trials were conducted with a five-minute rest between runs. Motor-evoked potentials (MEP) were recorded during stimulation and at 0, 10, 20, and 30 min after stimulation. The MEP amplitudes after intervention were normalized to the mean pre-intervention MEP amplitude and expressed as MEP ratios. An additional test with TUS alone was applied to all participants to assess whether TUS itself can elicit after-effects. Results There were no significant after-effects of all three interventions on MEP ratios. However, 11 subjects who showed online inhibition (OI + ) during the TUS-TMS-C protocol, defined as having MEP ratio less than 1 during TUS-TMS-C, showed significant MEP suppression at 10, 20 and 30 min after TUS-TMS-C. In 8 subjects did not show online inhibition (OI-), defined as having MEP ratios greater than 1 during TUS-TMS-C, showed no significant inhibitory after-effects. OI + and OI- status did not change in a follow-up repeat TUS-TMS-C test. TUS alone did not generate inhibitory after-effects in either OI + or OI- participants. Conclusions Our results showed that co-delivery of TUS and TMS can elicit inhibitory after-effect in subjects who showed online inhibition, suggesting that TUS and TMS may interact with each other to produce plasticity effects. Significance TUS and TMS may interact with each other to modulate cortical excitability.
Abstract via europepmc.
Exposures
Exposure 1: TUS_0.5 (motor cortex TUS-TMS co-stimulation)
Target: primary motor cortex — “motor cortex (FDI hotspot)”
Device: Sonic Concepts · Sonic Concepts Inc · H246 ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 0.3 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 30pulse duration × PRF gives 30% | ✓✓✓ |
| Sonication duration (s) | 0.5 | ✓✓✓ |
| Free-field pressure (kPa) | 612 | ✓✓✓ |
|---|---|---|
| Free-field Isppa (W/cm²) | 9.38 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 2.81 | ✓✓✓ |
| In-situ estimate | deratingsingle value | |
| In-situ pressure (kPa) | 183.6 | ✓✓✓⚑ |
| In-situ Isppa (W/cm²) | 0.84 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.252 | ✓✓✓ |
Each paradigm included two sets of 30 trials of stimulation separated by 5 min (60 trials total), trials delivered 5 s apart. TUS-TMS-C delivered TMS 10 ms before the end of the 500 ms sonication (0.49 s after onset); TUS-TMS-S delivered TMS 2.5 s after the end of sonication (3 s after onset); TMS only used identical timing with TUS stimulation intensity set to 0 W.
Flags from extraction
exposures[0].in_situ.pressure_kpa— In-situ pressure/intensity derived by assuming a 30% (70% drop) transmission based on a literature range (Liu et al., 2014), not measured or simulated for this cohort's skulls.exposures[0].timing.pulse_duration_ms— Paper states PRF (1000 Hz), duty cycle (30%) and sonication duration (500 ms) but never states pulse duration explicitly; not computed per protocol.blinding— Paper does not explicitly state whether participants/experimenters were blinded to TUS-TMS-C/S vs TMS-only conditions beyond masking sound.