Fig. 1: Overview of the block design, experimental setup, and behavioral paradigm.
a Randomized study group assignment. Sixty subjects were randomly assigned to one of two groups, each consisting of 30 participants, corresponding to either a 70% or 5% DC. 54 participants (27 per group) were included in the final analysis. b The timeline of experimental sessions, including initial preparation steps and the main task. The main task included two outer baseline blocks and four inner LIFU-ON blocks with a pseudo-randomized order of targeting regions. Each block comprised 100 trials. Each LIFU-ON block included 23 alternating 30-second ON and OFF epochs (total 11.5 min). Visual tasks were conducted continuously within each block. Each ON epoch consists of 300 pulses (pulse repetition frequency = 10 Hz) at a fixed DC and temporal-average intensity (Ispta.3 = 0.72 W cm−2). The pulse-averaged intensity was higher at 5% DC. c Measurement locations for head size, including width, depth, and side-to-top. d Illustration of the transducer fixed by two perpendicular rubber bands on the participant’s head. e Sagittal view for the four target regions, including left VA, VP, DA, and DP. f Examples of real and scrambled images for each category (face, house, human-made object, and animal). g Example of an animal image displayed at different contrast levels. h Trial structure showing the sequence of events: a blank period, stimulus presentation, delay, and two questions about categorization and recognition. i Illustration of the four trial types (hit, miss, false alarm, and correct rejection). Due to copyright limitations, the actual images used in our experiment are not shown. Copyright-free images included in this figure were obtained from https://www.pexels.com. DC duty cycle, VA ventroanterior thalamus, VP ventroposterior thalamus, DA dorsoanterior thalamus, DP dorsoposterior thalamus.
