Heart activities are governed by the sympathetic and parasympathetic nervous system. Changes in these neural signals influence the development of arrhythmias, including ventricular tachyarrhythmias that often progress to sudden cardiac death (SDC). A simultaneous study of the cardioneural signals with the electrical heart activity can elucidate the mechanism of abnormal heart activity. In this work, we identify the locations to detect cardioneural signals. We first perform a 108 channel measurement to explore the cardioneural signals. We then focus on selected locations for longer period measurement. We monitor the changes in the heart rate following each sympathetic or vagal nerve activity. The neural signals are extracted from ECG by applying independent component analysis. The work provides a promising approach for studying the association of cardioneural signals with electrical heart activity.