An apparatus provides an electrical interface with a lumen in a body of an animal. The apparatus has a self-anchoring lead structure for implantation inside the lumen and includes at least two insulated conductors each connected to a separate electrode. Each electrode has an associated shape memory material and a rounded terminus to grip the lumen wall for anchoring the lead when properly positioned. The conductor for each electrode also is connected to a control circuit that programmably selects electrodes for electrically interfacing with the lumen. The self-anchoring lead structure has a contracted state for insertion into the animal and an expanded stated in which the electrode termini engage a wall of the lumen.