Enhancing Meditative Development with Transcranial Focused Ultrasound: A Mixed-Methods Phenomenological Study of Neuromodulation in Experienced Meditators During a Ten-Day Retreat
Sebastian Ehmann, Brian Lord, Erica Cook, Henry B. Brookman, Joaquin Roces, Tucker Peck, Shinzen Young, Matthew Sacchet, John JB Allen, Joseph Lacoste Sanguinetti
2025 · 10.31234/osf.io/uxrwy_v2
Abstract
Emerging research suggests some of the most profound meditation-induced psychological transformations require mastery of mental skills that enable access to advanced meditative states, stages, and endpoints. Such development, however, often demands years of sustained practice and expert guidance. Transcranial focused ultrasound (tFUS) offers a novel means of potentially supporting meditative development by modulating brain structures with high spatial precision. Suppression of the posterior cingulate cortex (PCC)—a hub of self-referential processing—may reduce stickiness in internal cognitions and self-interference, thereby fostering equanimity, a crucial meditative faculty. This pilot feasibility study investigated the effects of tFUS-based PCC inhibition during a ten-day silent retreat. Twenty-eight meditators received two stimulation sessions during the retreat and completed standardized questionnaires and daily phenomenological reports. Quantitative analyses revealed significant increases in trait mindfulness, both state–trait nondual awareness, and interoceptive body listening. Qualitative analyses identified consistent differences between stimulation and non-stimulation days: tFUS was associated with enhanced meditative phenomenology, including equanimity, concentration, and sensory clarity, as well as shifts in self-perception and cathartic emotional release. These experiential effects often unfolded in interaction with participants’ ongoing psychological challenges, suggesting that tFUS may increase baseline equanimity and scaffold meditative capacities. Implementation was feasible but required logistical planning. Limitations include the quasi-experimental design, reliance on self-reports, and lack of long-term follow-up. Future studies should use randomized sham-controlled designs, neurophenomenological methods, and examine systematic dose–response parameters with MRI-guided targeting. Together, these findings highlight tFUS as a promising tool for augmenting meditation training and advancing the study of meditative development.
Abstract via europepmc.
Exposures
Exposure 1: tFUS to the PCC during a ten-day retreat
Target: posterior cingulate cortex — “PCC”
Device: Blatek · Blatek · AT35246 transducer (custom-made single-channel system) ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 5 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 5pulse duration × PRF gives 500%, which disagrees with the stated value | ✓✓✓ |
| Sonication duration (s) | 5 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
500 kHz, 1000 Hz PRF, 5 ms pulses, 5% duty cycle; during each 10-minute session the device alternated 5 s on and 10 s off. Two sessions on nonconsecutive days, three or four days apart.
Consistency checks: pd exceeds period.
Flags from extraction
n_subjects— 29 received tFUS; 28 analysed (one excluded for missing post-retreat data). Comparison group (n = 6) received no tFUS and was excluded from analysis.exposures[0].timing.sonication_duration_s— Taken as the 5 s on-period of an alternating 5 s on / 10 s off schedule over 10 minutes.sham_type— Non-equivalent comparison group who were ineligible or declined; no sham stimulation.exposures[0].device.family— Described as a custom-made system but the transducer is named as Blatek AT35246; family set by transducer maker.