Systems and methods for diagnosing and treating tissue transmit an electrical energy pulse that temporarily stuns a zone of tissue, temporarily rendering it electrically unresponsive. The systems and methods sense an electrophysiological effect due to the transmitted pulse. The systems and methods alter an electrophysiological property of tissue in or near the zone based, at least in part, upon the sensed electrophysiological effect. The alteration of the electrophysiological property can be accomplished, for example, by tissue ablation or by the administration of medication. In a preferred implementation, radio frequency energy is used to both temporarily stun tissue and to ablate tissue through a common electrode.