A system and method to map a biological tissue of alternating electrical polarity having a boundary between a depolarized portion and a polarized portion is provided. The system includes a computer, a transducer probe, and a receiver. The transducer probe is in communication with the computer and configured to transmit acoustic waves at a frequency through the biological tissue of alternating electrical polarity. The receiver is in communication with the computer and operable to detect a variation in an electrical activity at approximately the frequency of the acoustic waves. The computer creates a display of at least a portion of the variation in the electrical activity at approximately the frequency of the acoustic waves.