Transcranial ultrasound stimulation of the pulvinar and globus pallidus internus facilitates visual search
Hamidreza Ramezanpour, Ghazaleh Darmani, Regina Annirood, Can Sarica, Jean-Francois Nankoo, Samuel Pichardo, Jeffrey D. Schall, Andres M. Lozano, Robert Chen
iScience 2026, 29, 116316 · 10.1016/j.isci.2026.116316
Abstract
Ultrasound offers a powerful means of modulating human cognition by noninvasively targeting subcortical structures previously accessible only via invasive procedures. While decades of research have mapped cortical circuits of attention, deep hubs such as the basal ganglia and thalamus are increasingly recognized as key nodes in attention networks. We tested whether low-intensity transcranial ultrasound stimulation (TUS) of the globus pallidus internus (GPi) and pulvinar modulates visual search, an attention-dependent task, predicting site-specific effects that reflect distinct basal ganglia-thalamic circuit functions. Focal TUS reduced reaction times, suggesting a facilitation of attention-related task performance. A dissociation emerged across sites: stimulation of both GPi and pulvinar reduced reaction times, but pulvinar yielded more robust benefits for target-present trials at peripheral eccentricities, and improved search efficiency in the same trials. These results support distinct contributions of basal ganglia and thalamic nodes to attention-related behavior and show that TUS can be used to probe circuit-level mechanisms of cognition in humans.
Abstract via europepmc.
Exposures
Exposure 1: GPi TUS
Target: globus pallidus internus — “globus pallidus internus (GPi)”
Device: Sonic Concepts · Sonic Concepts ✓
| Waveform | theta burst | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 20 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 5 | ✓✓✓ |
| Duty cycle (%) | 10pulse duration × PRF gives 10% | ✓✓✓ |
| Sonication duration (s) | 120 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 30 | ✓✓✓ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | simulationmean or range across subjects | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 2.5, 7swept | ✓?⚑ |
| In-situ Ispta (W/cm²) | 0.25, 0.7swept | ✓✓✓ |
A theta-burst TUS (tbTUS) protocol consisting of 20 ms bursts at 50 Hz repeated every 200 ms (10% duty cycle) was delivered for 120 s to each hemisphere in turn (bilateral). Behavioral testing occurred in three blocks per session: baseline (Pre), immediately after sonicating the first hemisphere (Post-1), and after sonicating the second hemisphere (Post-2).
Exposure 2: Pulvinar TUS
Target: pulvinar — “pulvinar nucleus of the thalamus”
Device: Sonic Concepts · Sonic Concepts ✓
| Waveform | theta burst | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 20 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 5 | ✓✓✓ |
| Duty cycle (%) | 10pulse duration × PRF gives 10% | ✓✓✓ |
| Sonication duration (s) | 120 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 30 | ✓✓✓ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | simulationmean or range across subjects | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | 2.5, 7swept | ✓? |
| In-situ Ispta (W/cm²) | 0.25, 0.7swept | ✓✓✓ |
A theta-burst TUS (tbTUS) protocol consisting of 20 ms bursts at 50 Hz repeated every 200 ms (10% duty cycle) was delivered for 120 s to each hemisphere in turn (bilateral). Behavioral testing occurred in three blocks per session: baseline (Pre), immediately after sonicating the first hemisphere (Post-1), and after sonicating the second hemisphere (Post-2).
Flags from extraction
exposures[0].timing.pulse_duration_ms— Protocol described as '20 ms bursts at 50 Hz repeated every 200 ms (10% duty cycle)'; the stated duty cycle (10%) and period (200 ms, i.e. PRF=5 Hz) are consistent with a 20 ms burst duration, but the paper also cites '50 Hz' without stating how it fits the 20 ms/200 ms burst structure; recorded pulse_duration=20 ms and PRF=5 Hz as the values consistent with the stated duty cycle, and flagged for the unresolved '50 Hz' term (put in protocol_description).exposures[0].in_situ.isppa_w_cm2— Methods reports in-brain ISPPA as 2.5-7 W/cm2 (with ISPTA 0.25-0.7 W/cm2), while the Discussion separately states 'ISPPA ≈ 2-8 W/cm2 in brain'; the two ranges differ slightly. The more detailed Methods range (2.5-7) was used.blinding— Participants were blind to which structure (GPi vs pulvinar) was targeted in each session, but were not blinded to stimulation timing (transducer removal made stimulation offset apparent) and there was no sham condition; coded as single (blinding to stimulation target only).sham_type— The paper explicitly states there was no sham condition ('The absence of a sham condition ... leave open the possibility of expectation-related effects').randomised— The order of GPi vs pulvinar sessions was randomized across participants; there was no sham/control arm to randomize against.