Fig. 1: Methods.

A The experiment consisted of applying neuromodulation to eyes-closed resting-state humans. Transcranial electro-acoustic stimulation (tEAS) involved overlapping transcranial focused ultrasound (tFUS) and transcranial direct current stimulation (tDCS). The tFUS condition consisted of only tFUS. The tDCS control condition also involved a spatial control ultrasound, which did not overlap with the region enclosed by tDCS electrodes, to account for possible auditory confounds. B A diagram of the experimental set up for each condition is provided with tDCS electrodes and ultrasound transducers placed on their relative location to EEG electrodes. C A free water scan of ultrasound is provided to illustrate its 5 mm full-width half-max (−6 dB) spatial specificity. D For the experiment, 500 kHz fundamental frequency (f₀) ultrasound was pulsed every two seconds with up to an additional 20% random jitter for 200 trials. The pulse repetition frequencies (PRFs) were either 30 Hz or 3 kHz, as specified. The cycles per pulse (CPP) and pulse number (PN) varied based on PRF to normalize all conditions to 500 ms sonication duration and a 30% duty cycle. For conditions involving tDCS, the electrical stimulation remained on throughout the entirety of the trials. Head model icon created in BioRender. Kosnoff, J. (2026) https://BioRender.com/38kr3b9.