Imaging current flow in lobster nerve cord using the acoustoelectric effect

Ultrasound traversing a biologic fluid or tissue generates a local change in electrical conductivity known as the acoustoelectric effect. The authors exploit this interaction to image ionic current injected into the abdominal segment of the lobster nerve cord. A pair of recording electrodes detected the acoustoelectric signal induced by pulses of focused ultrasound (1.4 or 7.5 MHz). The signal was linear with injected current at 2 MPa (0.7 μV/mA cm ²) and pressure at 75 mA/cm² (23 μV/MPa). Acoustoelectric imaging of biocurrents potentially enhances spatial resolution of traditional electrophysiology and merits further study as an imaging modality for neural applications.