A Noninvasive Focused Ultrasound-Evoked Electrophysiological Mapping Method With High Spatiotemporal Precision.

Abstract

Achieving noninvasive functional brain mapping with submillimeter spatial and millisecond temporal resolution remains a major technical challenge. Existing modalities fail to meet both requirements simultaneously: fMRI offers high spatial resolution but suffers from hemodynamic delays, while EEG provides superior temporal resolution yet lacks spatial specificity. We present a cortical mapping method that integrates focused ultrasound (FUS) stimulation with local field potential (LFP) recordings for high-resolution electrophysiological mapping. A 5 × 5 Cartesian scanning grid was applied over the barrel cortex. FUS pulses (4 MHz, 1.6 MPa peak negative pressure, 1Hz pulse repetition frequency) were sequentially delivered to each grid point, and peak LFP amplitudes were recorded at each site via a tungsten microelectrode to generate activation heatmap. Our method achieved approximately 0.45 mm spatial resolution and 10 ms temporal resolution in detecting FUS evoked LFP responses. The proposed FUS-LFP mapping paradigm enables high-resolution and time-precision visualization of cortical electrophysiological responses to noninvasive stimulation. This method provides a robust and scalable approach for probing evoked cortical responses and constructing functional brain maps, with promising translational relevance for preclinical neuroengineering.