An electrode array has a flexible body supporting a plurality of electrodes. Each electrode comprises an exposed connector pad at the upper end of the body, an exposed recording/stimulating pad at the lower end of the body, and a conductor located within the body and electrically connecting the connector pad and the recording/stimulating pad. In one embodiment the electrode array has an elongated recording/stimulating portion coiled or folded to distribute the exposed recording/stimulating pads in three dimensions. An implantation method employs an introducer with a helical portion to which an end of the flexible electrode is attached. The helical portion straightens to pass through a small-diameter cannula and then resumes its helical configuration to place the recording/stimulating portion of the attached electrode in a helix within the patient's tissues.