1. A system for applying electrical stimulation to a patient's brain, comprising: an implantable housing; a pulse generator carried by the implantable housing, the pulse generator having a first terminal and a second terminal, the pulse generator being configured to deliver to at least one of the first and second terminals a stimulation signal having a plurality of stimulation periods with at least one of the stimulation periods having a duration of about 30 seconds or less; at least one first electrode carried by the housing and operatively coupled to at least one of the first and second terminals; and at least one second electrode carried by the housing and operatively coupled to at least one of the first and second terminals, wherein the housing includes a first portion and a second portion, and wherein the at least one first electrode is carried by the first portion of the housing so as to be positioned at a cortical stimulation site of the patient located at least approximately at or below an inner surface of the patient's skull when the housing is implanted, and wherein the at least one second electrode is carried by the second portion of the housing so as to be positioned at least approximately at or above an outer surface of the patient's skull and beneath the patient's scalp when the housing is implanted.