Targeting central thalamus with transcranial ultrasound reduces arousal in healthy volunteers

Using low-intensity focused transcranial ultrasound stimulation, we test the causal roles of the central thalamus in arousal and the pulvinar in visuospatial attention in the healthy human brain. In a within-subjects, counterbalanced design, 27 healthy volunteers (two females) complete a vigilance task (Psychomotor Vigilance Task) and a visuospatial attention task (Egly-Driver Task) before and after sham, central thalamic, and pulvinar sonication. Targeting the central thalamus slows responses and increases lapses in attention during the vigilance task, indicating reduced arousal. Pulvinar sonication reduces (and slows) responses to visual stimuli presented contralaterally, suggesting a disruption of contralateral visuospatial attention. These results provide causal evidence linking the pulvinar to visuospatial attention and the central thalamus to arousal in the healthy human brain and demonstrate that ultrasound can elicit distinct behavioral changes in healthy volunteers when delivered to close but functionally distinct thalamic regions, underscoring its potential as a tool for noninvasive brain mapping.