The probe has support cylinder (214) that is slidingly provided in distal portion of internal lumen. Several shafts coupled to support cylinder and arranged to be selectively extended from distal end of elongated shaft. Several conductive traces provided on insulative layer of planar substrate of microelectrode element (300). A stylet provided in internal lumen and configured to contact support cylinder to selectively extend shafts during implantation. A pull wire coupled to support cylinder to selectively retract support cylinder and shafts within internal lumen.