Behavioral effects of targeting the central thalamus and pulvinar with transcranial ultrasound stimulation in healthy volunteers
Amber R. Hopkins, Joshua A. Cain, Elizabeth A. White, Stephanie M. Abakians, Martin M. Monti
2025 · 10.1101/2025.02.27.640692
Abstract
We present the first causal evidence in the healthy human brain linking the central thalamus to vigilance and the pulvinar to visuospatial attention using low-intensity transcranial focused ultrasound stimulation (tFUS). In a within-subjects, counterbalanced design, 27 healthy volunteers completed the Psychomotor Vigilance Task (PVT), a vigilance task, and the Egly-Driver Task (EDT), which assesses visuospatial attention, before and after central thalamus, pulvinar, and sham sonication with tFUS. Central thalamic sonication significantly impaired performance on both tasks in a manner consistent with decreases in arousal. Targeting the pulvinar with tFUS resulted in more subtle changes in visuospatial attention. Participants were less reactive to visual stimuli presented in the visual field contralateral to the affected pulvinar. These results demonstrate that tFUS can elicit measurable behavioral changes in healthy volunteers and underscores its potential as a high-resolution tool for non-invasive brain mapping, capable of differentiating functional contributions of thalamic regions only millimeters apart.
Abstract via europepmc.
Exposures
Exposure 1: Central thalamus (left)
Target: thalamus — “central thalamus”
Device: BrainSonix · Brainsonix Corp. · BXPulsar 1002 drive system with fixed-focal-length single-element spherical transducer (80 mm focal length, 61 mm aperture) ✓
| 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) | 30 | ✓✓✓ |
| 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) | 14.4 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.72 | ✓✓✓ |
Ultrasound was delivered in an on/off block design including 10 blocks with 30 seconds of sonication and 30 seconds of rest (30 s pulse train duration; 0.5 ms pulse duration, 100 Hz PRF, 5% duty cycle). Tasks (PVT and EDT) were run before and after sonication in each session; sessions at least 24 hours apart.
Exposure 2: Pulvinar (left)
Target: pulvinar — “pulvinar”
Device: BrainSonix · Brainsonix Corp. · BXPulsar 1002 drive system with fixed-focal-length single-element spherical transducer (80 mm focal length, 61 mm aperture) ✓
| 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) | 30 | ✓✓✓ |
| 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) | 14.4 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.72 | ✓✓✓ |
Ultrasound was delivered in an on/off block design including 10 blocks with 30 seconds of sonication and 30 seconds of rest (30 s pulse train duration; 0.5 ms pulse duration, 100 Hz PRF, 5% duty cycle). Tasks (PVT and EDT) were run before and after sonication in each session; sessions at least 24 hours apart.
Flags from extraction
exposures[0].timing.pulse_repetition_frequency_hz— Methods text gives a 60 s pulse repetition interval while the Figure 1 legend gives a 10 ms PRI (100 Hz PRF); recorded the stated 100 Hz PRF and 5% duty cycle.exposures[0].unspecified_domain.isppa_w_cm2— Intensities are labelled Ispta.3 / Isppa.3 (derated notation) but the paper does not say whether they are free-field or in situ; placed in unspecified_domain. Given as upper bounds (<=720 mW/cm2, <=14.40 W/cm2). Methods write '<' and the legend writes '<='.exposures[1].unspecified_domain.isppa_w_cm2— Same intensity statement applies to both targets; domain not stated.exposures[0].target.terms— Central thalamus 'includes the intralaminar thalamic nuclei and adjacent areas'; mapped to generic thalamus.direction_of_effect— Behavioural impairment after central thalamic sonication; authors suggest this is consistent with suppression but no neural readout was recorded.blinding— Only participants stated to be blinded; experimenter blinding not stated.