In Vivo Transcranial Measurement of Brain-Activated Sources With Acoustoelectric Brain Imaging

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 article first 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 signal-noise-ratio (SNR) of transcranial AE signal were 15.51 and 39.04 dB, 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 steady-state visual evoked potential (SSVEP) in spectrum response, power change, and waveform change. Within the 3
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3 mm and 5
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3 mm 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 1.5 mm. 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 toward the noninvasive detection of high spatiotemporal brain electrical activity.