Methods and apparatus for electrode placement and tracking

A headband comprising:

• a backing configured for placement upon a head of a patient;
• and
• a plurality of electrode assemblies distributed over a length of the backing,
• wherein one or more of the plurality of electrode assemblies comprises an upper body portion and a lower body portion, wherein the upper body portion comprises a reservoir containing an electrically conductive fluid or gel, wherein the lower body portion is rotatably mounted to the backing and comprises at least one elongate member, wherein the at least one elongate member comprises a tissue-contacting surface and a lumen having a distal opening, the tissue-contacting surface having a recess and a skin preparation surface, and wherein the one or more electrode assemblies is configured to deliver the electrically conductive fluid or gel from the reservoir through the distal opening of the lumen and through the recess, and
• wherein another one or more of the plurality of electrode assemblies are configured without an elongate member.