Transcranial focused ultrasound to the posterior cingulate cortex modulates default mode network and subjective experience: an fMRI pilot study
Brian Lord, Joseph L. Sanguinetti, Lisannette Ruiz, Vladimir Miskovic, Joel Segre, Shinzen Young, Maria E. Fini, John J. B. Allen
Frontiers in Human Neuroscience 2024, 18 · 10.3389/fnhum.2024.1392199
Abstract
Background Transcranial focused ultrasound (TFUS) is an emerging neuromodulation tool for temporarily altering brain activity and probing network functioning. The effects of TFUS on the default mode network (DMN) are unknown. Objective The study examined the effects of transcranial focused ultrasound (TFUS) on the functional connectivity of the default mode network (DMN), specifically by targeting the posterior cingulate cortex (PCC). Additionally, we investigated the subjective effects of TFUS on mood, mindfulness, and self-related processing. Methods The study employed a randomized, single-blind design involving 30 healthy subjects. Participants were randomly assigned to either the active TFUS group or the sham TFUS group. Resting-state functional magnetic resonance imaging (rs-fMRI) scans were conducted before and after the TFUS application. To measure subjective effects, the Toronto Mindfulness Scale, the Visual Analog Mood Scale, and the Amsterdam Resting State Questionnaire were administered at baseline and 30 min after sonication. The Self Scale and an unstructured interview were also administered 30 min after sonication. Results The active TFUS group exhibited significant reductions in functional connectivity along the midline of the DMN, while the sham TFUS group showed no changes. The active TFUS group demonstrated increased state mindfulness, reduced Global Vigor, and temporary alterations in the sense of ego, sense of time, and recollection of memories. The sham TFUS group showed an increase in state mindfulness, too, with no other subjective effects. Conclusions TFUS targeted at the PCC can alter DMN connectivity and cause changes in subjective experience. These findings support the potential of TFUS to serve both as a research tool and as a potential therapeutic intervention.
Abstract via europepmc.
Exposures
Exposure 1: TFUS to the posterior cingulate cortex (PCC)
Target: posterior cingulate cortex — “ventral posterior cingulate cortex (PCC)”
Device: Sonic Concepts · Sonic Concepts · custom 4-channel ring transducer, 64 mm outer diameter ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 5 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 10.53 | ✓✓✓ |
| Duty cycle (%) | 5.26pulse duration × PRF gives 5.263% | ✓✓✓ |
| Sonication duration (s) | 30 | ✓✓✓ |
| Free-field pressure (kPa) | 421.6 | ✓✓✓ |
|---|---|---|
| Free-field Isppa (W/cm²) | 5.58 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 0.293 | ✓✓✓ |
| In-situ estimate | measurementsingle value | |
| In-situ pressure (kPa) | 129.6 | ✓✓✓ |
| In-situ Isppa (W/cm²) | 0.46 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.024 | ✓✓✓ |
TFUS was delivered as 30-s stimulus intervals followed by 30-s rest periods, repeated five times consecutively for a total session duration of 5 min, using MRI-guided neuronavigation with the beam focused at a fixed distance of 55 mm (average scalp-to-PCC distance).
Flags from extraction
n_subjects— n=15 per condition (30 total enrolled, 15 active + 15 sham); only the active-TFUS group (n=15) is counted as exposed to real ultrasound.n_sessions_per_subject— The Methods describe a single TFUS/sham application per subject but do not state an explicit session count in a single sentence; inferred from the single-application procedure description.