Transcranial focused ultrasound modulates the activity of primary somatosensory cortex in humans

Existing noninvasive neuromodulation methods have poor spatial resolution and may affect neural activity in both the targeted cortical region and unintended surrounding networks. The authors demonstrate that transcranial focused ultrasound, a noninvasive technique with better spatial specificity, can alter neural activity within spatially confined regions of primary somatosensory cortex and enhance somatosensory discrimination. Improved methods of noninvasively modulating human brain function are needed. Here we probed the influence of transcranial focused ultrasound (tFUS) targeted to the human primary somatosensory cortex (S1) on sensory-evoked brain activity and sensory discrimination abilities. The lateral and axial spatial resolution of the tFUS beam implemented were 4.9 mm and 18 mm, respectively. Electroencephalographic recordings showed that tFUS significantly attenuated the amplitudes of somatosensory evoked potentials elicited by median nerve stimulation. We also found that tFUS significantly modulated the spectral content of sensory-evoked brain oscillations. The changes produced by tFUS on sensory-evoked brain activity were abolished when the acoustic beam was focused 1 cm anterior or posterior to S1. Behavioral investigations showed that tFUS targeted to S1 enhanced performance on sensory discrimination tasks without affecting task attention or response bias. We conclude that tFUS can be used to focally modulate human cortical function.