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Nature CommunicationsNeurosciencePeer-reviewed journal article

Transcranial focused ultrasound-mediated neurochemical and functional connectivity changes in deep cortical regions in humans

Siti N. YaakubiD, Tristan A. White, Jamie RobertsiD, Eleanor M. MartiniD, Lennart VerhageniD, Charlotte Jane StaggiD, Stephen Hall, Elsa Florence FouragnaniD

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Abstract

Low-intensity transcranial ultrasound stimulation (TUS) is an emerging non-invasive technique for focally modulating human brain function. The mechanisms and neurochemical substrates underlying TUS neuromodulation in humans and how these relate to excitation and inhibition are still poorly understood. In 24 healthy controls, we separately stimulated two deep cortical regions and investigated the effects of theta-burst TUS, a protocol shown to increase corticospinal excitability, on the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and functional connectivity. We show for the first time in humans that theta-burst TUS selectively reduces GABA levels in the posterior cingulate, but not the dorsal anterior cingulate cortex. Functional connectivity increased following TUS in both regions. Our findings suggest that TUS changes overall excitability by reducing GABAergic inhibition, that changes in TUS-mediated neuroplasticity last at least 50 minutes after stimulation, and that these effects may be state-dependent - a mechanism increasingly recognized to influence the brains response to neuromodulation.

In-depth summary

Claude Opus 5.5 · xhigh effort · 8 Nov 2026 · from the full text of version 1 (20 Jan 2023) · CC BY 4.0

Theta-burst transcranial ultrasound lowered GABA+ in the posterior cingulate but not dorsal anterior cingulate cortex in 24 adults, while raising resting-state connectivity of both targets.

Low-intensity transcranial ultrasound stimulation (TUS) can focally reach deep brain targets, but how its lasting effects relate to excitation, inhibition and neurochemistry in humans was unclear, and magnetic resonance spectroscopy (MRS) had not been used to probe it. Pairing MRS with resting-state fMRI and per-subject acoustic simulations, the study tests GABA, glutamate and network effects of sonicating two deep cingulate regions versus sham.

Key results

  1. ShownTheta-burst TUS of the posterior cingulate cortex (PCC) lowered GABA+/water in the PCC voxel relative to both sham and dorsal anterior cingulate (dACC) stimulation, whereas dACC stimulation left dACC GABA+ unchanged and Glx/water did not differ between sessions in either voxel.

    GLM (covariates age, sex, in situ intensity, focal overlap with voxel) main effect of session F2,55 = 4.66, p = 0.013, η^2 = 0.141; PCC TUS vs sham t55 = −2.88, p = 0.017, d = −0.92; PCC vs dACC TUS t55 = −2.32, p = 0.048, d = −0.73; dACC TUS vs sham p = 0.570; target MRS at 22.3 ± 2.0 minutes post-TUS · TUS of the PCC selectively reduces GABA in the…; Spectroscopy data analysis; Results

  2. ShownSeed-based analysis using each subject's simulated focal volume as seed showed increased whole-brain connectivity of each target after its own sonication, broader in the later run; PCC stimulation also raised dACC-seed connectivity, but dACC stimulation did not alter PCC-seed connectivity.

    Cluster-corrected (Z > 2.3, cluster p = 0.05) vs mean of sham runs: dACC seed gained precuneus at ~13 min and thalamus, right putamen, parahippocampal and sensorimotor regions at ~46 min; PCC seed gained bilateral putamen at 13 min and auditory cortex and temporal pole at 46 min; no difference between the two sham runs. · TUS increases functional connectivity with the…; Functional MR data analysis: seed-based…

  3. ShownIndependent component analysis with dual regression showed stronger salience network connectivity after dACC TUS and stronger default mode network connectivity after PCC TUS, both emerging only in the later rsfMRI run and absent when the other region was stimulated.

    Networks defined by FSL MELODIC on sham sessions only; FSL randomise with 5000 permutations; significant differences only for run 2 at 46.0 ± 2.3 minutes post-TUS, not run 1 at 13.1 ± 2.0 minutes; no salience or default mode change after sonicating the non-associated region. · TUS increases functional connectivity of the…; Functional MR data analysis: resting-state…; Results

  4. SuggestedPer-participant pseudo-CT acoustic simulations indicated both deep cingulate targets were reached in all 24 participants within US FDA intensity and mechanical index limits, with the focus largely overlapping the MRS voxel; the beam was more elongated at the deeper PCC depth.

    Free field at 54.5 W/cm^2: 1.28 MPa, mechanical index 1.8; axial FWHM 32.1 mm at 60 mm vs 39.4 mm at 69 mm depth; mean transcranial intensity attenuation approximately 58%; peak skull heating 1.48°C and 1.88°C in the two highest-attenuation participants (below 2°C); focal volume vs in situ peak intensity r = −0.63, p = 1.31 × 10^-6 · Characterising the ultrasound waveform with free…; Transcranial acoustic simulations; Acoustic simulations

  5. SuggestedFew side effects were reported: three participants noted extra fatigue, one had a mild headache after dACC TUS that resolved within a day, and one felt a cool sensation after PCC TUS; participants without symptoms could not tell TUS from sham sessions.

    Next-day open-ended symptom questionnaire: three participants reported extra fatigue, one a mild headache resolving within a day, one a cool sensation lasting a few hours; sham used a powered-off transducer over mid-cingulate plus bone-conduction sound mimicking the pulse pattern. · Side effects associated with TUS; Ultrasound stimulation

Methods, data and reproducibility

Counterbalanced, sham-controlled within-subject design: 80 s theta-burst TUS (500 kHz; 20 ms pulses, 200 ms repetition interval) to dACC or PCC, then 3T MEGA-PRESS MRS at target and control voxels and two 5-minute rsfMRI runs analysed by seed-based and ICA/dual-regression connectivity; per-subject pseudo-CT k-Wave simulations checked targeting and safety.

  • Healthy adult volunteers (14 female, aged 22 to 53 years) completing an MRI-only visit plus counterbalanced dACC TUS, PCC TUS and sham sessions · human · n = 24
  • MEGA-PRESS single-voxel spectra (2 × 2 × 2 cm^3) at TUS target and control cingulate voxels each session, quantified as GABA+/water and Glx/water · human · n = 24 participants
  • Two 5-minute multiband resting-state fMRI runs per session (2.5 mm isotropic voxels, 2000 ms TR) · human · n = 24 participants
  • T1-weighted MRI: a per-session MPRAGE (1 mm^3) for MRS voxel planning, plus a high-resolution scan used for neuronavigation, pseudo-CT skull models and acoustic simulations · human · n = 24 participants
  • Human Protein Atlas transcriptomic data, cited in the Discussion for possible regional ion-channel expression differences between PCC and dACC · human (Human Protein Atlas)
Methods & tools
NeuroFUS TPO with CTX-500-4 four-element transducer (Brainbox Ltd.), Brainsight neuronavigation (Rogue Research), k-Wave Toolbox 1.3 with kArray (MATLAB R2020b), Deep-learning MR-to-pseudo-CT conversion (mr-to-pct), MEGA-PRESS MRS on Siemens MAGNETOM Prisma 3T, Gannet, SPM12, FSL FEAT 6.00 with FLAME1+2 mixed-effects model, FSL MELODIC ICA with dual regression, FSL randomise permutation testing, fslmotionoutliers
Data & accessions
https://osf.io/rp5g4/
Software & environment
k-Wave Toolbox version 1.3 with kArray, MATLAB R2020b; FSL FEAT Version 6.00; SPM12; Gannet; Siemens MAGNETOM Prisma 3T (VE11E) with 32-channel head coil
Reproducibility gaps
Further raw or processed data beyond the OSF deposit only on reasonable request to the corresponding author; MRS and fMRI statistical analysis scripts are not linked.
Limitations (5)
  • Each session had only one MRS acquisition at the target (22.3 ± 2.0 minutes post-TUS), so GABA dynamics during and right after stimulation, and the time needed to return to baseline, remain unknown. · stated by the authors
  • MEGA-PRESS is a GABA-editing sequence not optimised for Glx, and off-resonance Glx estimates may be less reliable in the dACC, so the null glutamate result is inconclusive; other sequences or higher field strength are proposed. · stated by the authors
  • No link emerged between inter-individual acoustic variability (focal volume, intensity) and GABA or connectivity change, but the authors caution this may not hold for targets where the skull is oblique to the beam or heterogeneous. · stated by the authors
  • The PCC versus dACC difference is interpreted post hoc as state dependence without a direct test; it is also confounded with target depth, beam elongation and larger focal overlap with the PCC MRS voxel, despite covariate adjustment. · noted in this summary
  • Effects rest on between-session comparisons with sham in 24 healthy adults without a within-session pre-stimulation baseline, and the PCC TUS vs dACC TUS GABA contrast (p = 0.048) sits near the significance threshold. · noted in this summary

Read this if you study non-invasive neuromodulation and want sham-controlled human MRS and resting-state fMRI evidence on how theta-burst ultrasound alters deep cingulate inhibition and network connectivity.

Citations
201
FWCI
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Field percentile
top 1%

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