Abstract: A lead for brain target localization in functional stereotactic brain surgery, the lead having at its distal end a micro-electrode for use in recording single cell discharge patterns so as to identify functional boundaries between brain structures; and a macro-electrode for delivering test stimulation for determining target location for optimal therapeutic benefit and minimum side effects. The macro-test stimulation electrode is carried at the end of the lead length, and has a conventional surface area in the range of 1-20 mm.sup.2 for stimulating chronic stimulation conditions. The micro-electrode is positioned at the distal end of an axially aligned probe which extends distally from the macro-electrode, and has a surface area adapted to enable a single cell recording; e.g., between 0.01 and 1000 .mu.m.sup.2. In an alternate embodiment, the tip micro-electrode is retractable so that the lead can be used for chronic brain stimulation.