Facilitating Meditation with Focused Ultrasound Neuromodulation: A First Investigation in Experienced Practitioners
Joshua Cain, Tracy Brandmeyer, Ninette Simonian, Joseph Sanguinetti, Shinzen Young, Matthew Sacchet, Nicco Reggente
2024 · 10.31234/osf.io/3bzg6
Abstract
This study aims to assess the validity of focused ultrasound (FUS) stimulation as a method for facilitating meditative development, which may have application for novice or intermediate meditators seeking to improve their practice. A growing body of work suggests profound benefits to health and wellbeing following consistent meditation practice; however, successfully maintaining such a practice proves to be difficult for many who attempt it. By leveraging what is known about the neural correlates of meditation, we investigate the possibility of lowering this barrier of entry via direct neuromodulation using FUS. Specifically, we applied ultrasound for 12 minutes to either the posterior cingulate cortex, bilateral caudate, or bilateral insula in experienced (vipassana) meditators while they engaged in their habitual mindfulness meditation across four separate one-hour sessions. Subjective effects reported during and after each meditation session involving stimulation are compared to a sham stimulation session, with significant differences considered evidence for an effect of FUS. Physiological effects are also reported. Our preliminary data (n=10) suggests a strong, significant improvement in self-reported meditative depth during/after Caudate stimulation while questionnaires taken after the meditation further suggest an augmented state of meditation as well as general mood induced by this condition. Compounding this, reduced heart rate and increased heart rate variability (compared to sham) were observed following FUS, again unique to the Caudate stimulation condition, while these measures were found to strongly correlate with reported depth, suggesting a mechanistic relationship between these adaptive changes in physiological arousal and successful meditation induced by targeting this structure.
Abstract via europepmc.
Exposures
Exposure 1: PCC
Target: posterior cingulate cortex — “PCC”
Device: BrainSonix · Brainsonix · single-element transducers with depths of 80mm, 65mm, and 35mm ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 650 | ✓✓✓ |
| Pulse duration (ms) | 0.5 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 5pulse duration × PRF gives 5% | ✓✓✓ |
| Sonication duration (s) | 10 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 30 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 1.5 | ✓✓✓ |
| In-situ estimate | simulationsingle value | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 2.94 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.147 | ✓✓✓ |
12 minutes of stimulation beginning after minute 12 of a 60-minute meditation, delivered in 10-second on-off blocks; for the bilateral targets 6 minutes to each hemisphere sequentially (PCC is a single transducer for 12 minutes).
Exposure 2: Bilateral caudate
Target: caudate nucleus — “bilateral heads of the caudate”
Device: BrainSonix · Brainsonix · single-element transducers with depths of 80mm, 65mm, and 35mm ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 650 | ✓✓✓ |
| Pulse duration (ms) | 0.5 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 5pulse duration × PRF gives 5% | ✓✓✓ |
| Sonication duration (s) | 10 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 30 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 1.5 | ✓✓✓ |
| In-situ estimate | simulationsingle value | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 2.3 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.115 | ✓✓✓ |
12 minutes of stimulation beginning after minute 12 of a 60-minute meditation, delivered in 10-second on-off blocks; for the bilateral targets 6 minutes to each hemisphere sequentially.
Exposure 3: Bilateral anterior insula
Target: anterior insula — “bilateral, anterior ventral insula”
Device: BrainSonix · Brainsonix · single-element transducers with depths of 80mm, 65mm, and 35mm ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 650 | ✓✓✓ |
| Pulse duration (ms) | 0.5 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 5pulse duration × PRF gives 5% | ✓✓✓ |
| Sonication duration (s) | 10 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 30 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 1.5 | ✓✓✓ |
| In-situ estimate | simulationsingle value | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 3.8 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.19 | ✓✓✓ |
12 minutes of stimulation beginning after minute 12 of a 60-minute meditation, delivered in 10-second on-off blocks; for the bilateral targets 6 minutes to each hemisphere sequentially.
Flags from extraction
n_subjects— Pre-registration with preliminary pilot data from 10 participants; planned sample is 36.exposures[0].free_field— Proposed intensities and the 2.1116 MPa simulation source pressure are not explicitly labelled as water or free field; Table 3 caption compares to FDA limits in a free medium, so placed in free_field.exposures[0].timing.sonication_duration_s— 10-second on-off blocks over 12 minutes; the on and off durations are inferred from the text '10-second on-off blocks' and '10 continuous seconds'.exposures[0].in_situ— Simulated in-situ intensity from a single Visible Human CT skull model, planning phase estimate.exposures[0].timing.pulse_duration_ms— Pulse width of 0.5 ms stated with 5% duty cycle and 100 Hz PRF.