Acoustoelectric brain imaging (ABI) is a potentially noninvasive neuroimaging method with high spatiotemporal resolution. Until now, ABI has been limited to intracerebral measurement, which restricts its application in brain science research. This paper firstly implements in vivo brain activated sources measurement with transcranial ABI. A binocular steady-state visual stimulation paradigm was designed and presented to living rats. Brain electrical signal and acoustoelectric (AE) signal of multi-cortexes were simultaneously detected by intracerebral and transcranial ABI. The AE signal measured by transcranial ABI was then decoded and imaged. The power-enhancement and SNR of transcranial AE signal were 15.51dB and 39.04dB, which were sufficient to ensure its accuracy and distinguishability. With different visual stimuli and pulse repetition frequencies, the decoded AE (dec-AE) signals were always significantly consistent with SSVEP in spectrum response, power change, and waveform change. Within the 3mm × 3mm and 5mm × 3mm scan areas, brain activation areas were located in the visual cortex, mapped by the amplitudes of multi-position dec-AE signals. The diameters of the activation regions were less than 1.5mm. In addition, the transient strength change of the activated area was revealed, which is consistent with the temporal evolution of SSVEP. Experiment results demonstrate that ABI is able to transcranial measure brain electrical signal and locate brain activation source with milli meter spatial and millisecond temporal resolution. This study extends ABI to transcranial measurement, which makes a critical step forward towards the noninvasive detection of high spatiotemporal brain electrical activity.

Ultrasound technology has become a highly promising tool in the field of neuroscience, particularly in brain imaging and neuromodulation. These techniques not only allow for non-invasive visualization of brain structure and functional activity but also enable precise modulation of neural activity, offering new perspectives for the diagnosis and treatment of brain diseases. Animal experiments and clinical studies have confirmed its effectiveness in brain research and therapeutic interventions. However, concerns regarding its safety remain. This review aims to systematically evaluate the safety of ultrasound-based brain imaging and neuromodulation. We examine the mechanisms that may lead to adverse effects, highlight key acoustic parameters that could impact safety, and summarize the acoustic parameters used in existing studies, along with their associated safety reports. The results indicate that, for ultrasound imaging, structural and hemodynamic imaging are generally safe, but prolonged exposure (>10 min) should still be avoided. For high-energy or microbubble-enhanced imaging techniques, strict control of the mechanical index, exposure duration, and microbubble dosage is necessary to minimize cavitation-induced damage. Regarding ultrasound modulation, diagnostic safety standards no longer apply-the safety threshold is significantly higher, with irreversible damage only occurring under high-intensity ultrasound (e.g.,ISPPA=280 W/cm² in rodent models) or when combined with microbubbles.Finally, we emphasize the need for further systematic safety studies and the development of more precise safety guidelines for different technical principles and application scenarios to ensure the safe use of ultrasound technology in neuroscience.

Transcranial acoustoelectric brain imaging (tABI) is a potential brain activity imaging technique with high spatiotemporal resolution. Precise focus of transcranial ultrasound is critical for realizing millimeter-level spatial resolution in tABI. In this study, a precise focusing simulation platform is proposed by constructing a high-precision 3D skull model from Bama pig computed tomography data and a mathematical model equation by considering the skull’s heterogeneous properties. Then, the delay parameters derived from the simulation platform improve the precision of transcranial ultrasound focusing, enabling precise localization of brain activation sources with tABI. Phantom experimental results demonstrate that the transcranial ultrasound field is precisely focused at the target with a 0.20 mm deviation when delay parameters are obtained from the proposed simulation platform, whereas it exhibits divergence when using delay parameters derived from pure water or homogeneous skull models. Furthermore, using the proposed simulation platform, tABI can accurately identify intracranial electrical signals of distinct frequencies and precisely locate the corresponding activation sources with a spatial deviation of 0.50 mm. These results demonstrate that the proposed simulation platform is a powerful tool for the precise focusing of tABI.

Brain imaging technologies can reveal the neural basis behind thoughts, emotions, and behaviors. Acousto-electric brain imaging is an emerging neuroimaging technique with high spatiotemporal resolution. This study designed and implemented multi-frequency steady-state visual evoked stimuli in rats to explore the classification performance of acousto-electric imaging. Canonical correlation analysis was used to classify the signals, and results were compared with traditional scalp electroencephalography (EEG) methods. The findings indicate that acousto-electric brain imaging is less affected by electrode placement (n.s.) compared to traditional EEG(*). However, the classification performance of ABI signals still lags behind traditional EEG when averaging trials and placing electrode optimally(****).