Leads and introduction tools are proposed for deep brain stimulation and other applications. Some embodiments of the present invention provide lead designs with which may be placed with a stylet, while others do not require a stylet. Some lead embodiments use standard wire conductors, while others use cable conductors. Several embodiments incorporate microelectrodes and/or microelectrode assemblies. Certain embodiments of the present invention provide introduction tools, such as cannula and/or cannula systems, which ensure proper placement of, e.g., leads.