Transcranial ultrasonic stimulation of central thalamus reduces arousal in healthy volunteers

We present the first causal evidence in healthy humans linking central thalamus to vigilance and 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 measure of vigilance, 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. Pulvinar sonication resulted in more subtle effects consistent with a selective disruption of visuospatial attention. Specifically, participants were less responsive to visual stimuli presented in the visual field contralateral to the targeted pulvinar. These results demonstrate that tFUS can elicit measurable behavioral changes in healthy volunteers and underscores its potential as a high-resolution tool for noninvasive brain mapping, capable of differentiating functional contributions of adjacent thalamic nuclei only millimeters apart.