Fig 1.
Acronyms used—CT: Computed tomography, aMRI: Anatomical magnetic resonance imaging, fMRI: Functional magnetic resonance imaging, rs-fMRI: Resting-state functional magnetic resonance imaging, NE: Neurological evaluation, SSEP: Somatosensory evoked potentials evoked by median nerve (m.n.) stimulation, FEP: FUS stimulation-mediated evoked potentials, EEG: Electroencephalography. S1: Primary somatosensory cortex, VPL: Ventral posterolateral nucleus.
Fig 2.
Schematics of experimental settings.
(A) FUS system that consists of (1) a control computer, (2) function generators, (3) amplifier, (4) impedance matching box, (5) voltage following circuit, (6) emergency stop button, (7) EEG data acquisition and median nerve stimulation system, (8) image-guidance infrared camera, (9) display monitor. (B) FUS transducer headgear for the S1 and VPL stimulation. (C) the spatial profiles of acoustic intensity of transducers for S1 stimulation and (D) VPL stimulation. The white arrows represent the sonication direction. Dotted white lines depict the regions of 90%-maximum of the intensity. (E) illustration of acoustic parameters: inter-stimulation interval (ISI), fundamental frequency (FF), duty cycle (DC), pulse duration (PD), pulse repetition frequency (PRF), sonication duration (SD), spatial-peak pulse-average intensity (Isppa).
Table 1.
Subjective reporting on tactile/auditory sensations and summary of individual numerical estimation of acoustic intensity and spatial errors of FUS stimulation based on numerical simulation.
Spatial errors were estimated using the focal coordinates obtained from the simulation and those obtained from the intended stimulation target.
Fig 3.
(A) SSEP from the left (red: F3-P3) and right (blue: F4-P4) hemispheres. (B) FEP acquired from different PD conditions. Kruskal-Wallis one-way ANOVA (p < 0.005) was conducted to compare FEP obtained from the four experimental conditions followed by post-hoc analysis for multiple comparisons (p < 0.005). The solid lines and shaded areas indicate group-average and standard errors, respectively.
Fig 4.
Frequency-specific comparisons of AEP.
Group-averaged AEP obtained from auditory stimulation of (A) both, (B) left and (C) right ears. Black and gray arrows indicate the timing of weak negative peaks appeared from binaural stimulation. Kruskal-Wallis one-way ANOVA (p < 0.005) was conducted to compare the four experimental conditions followed by post-hoc analysis for multiple comparisons (p < 0.005). No difference was detected. ADS: the duration of auditory stimulation. The solid lines and shaded areas indicate group-average and standard errors, respectively.
Fig 5.
The brain areas showing greater rsFC with respect to the sonicated (A) S1 and (B) VPL ~1 hour after the sonication (Visit #3 > Visit #1; Bonferroni corrected p < 0.05, minimum cluster size > 30 voxels).
A decrease in the rsFC was not detected. L: Left, R: Right, m: Medial, A: Anterior, P: Posterior, BA: Brodmann’s area, S1: Primary somatosensory area, VPL: Ventral posterolateral nucleus, MCC: Middle cingulate cortex, SMG: Supramarginal gyrus, IPL: Inferior parietal lobule, PrCG: Precentral gyrus, PoCG: Postcentral gyrus, PCL: Paracentral lobule, MTG: Middle temporal gyrus, ITG: Inferior temporal gyrus, IFG: Inferior frontal gyrus, STG: Superior temporal gyrus, MTG: Middle temporal gyrus, SFG: Superior frontal gyrus, SMA: Supplementary motor area.
Table 2.
Brain regions showing greater rsFC in Visit #3 compared to Visits #1 and #5 (i.e., Visit #3 > Visit #1 and Visit #3 > Visit #5) with respect to the sonicated seed areas, arranged in a descending order in terms of maximum t-value within the cluster (Bonferroni corrected p < 0.05 with a cluster size of a minimum 30 connected voxels).
The averaged rsFC levels (i.e., fisher’s z transformed correlation coefficient, r) at the brain regions across subjects were represented as the effect size. No significant change in rsFC patterns was observed comparing Visit # 1 > Visit #3 and Visit #5 > Visit #3.
Fig 6.
The brain areas showing reduced rsFC in ~1 month after the sonication (Visit #3 > Visit #5) with respect to the sonicated (A) right S1 and (B) right VPL (Bonferroni corrected p < 0.05, minimum cluster size > 30 voxels).
An increase in the rsFC was not detected. L: Left, R: Right, A: Anterior, P: Posterior, BA: Brodmann area. S1: Primary somatosensory area, VPL: Ventral posterolateral nucleus, PrCG: Precentral gyrus, PoCG: Postcentral gyrus, MCC: Middle cingulate cortex.