Experimental design and self-administration training data. (a) Timeline. (b) Number of infusions during self-administration sessions (mean±S.E.M.; saline, n=20 rats; cocaine, n=18 rats). (c) Representative 10x single plane confocal images showing nucleus accumbens core (AcbC) and shell (AcbSh) (top) and dorsolateral striatum (DLS) (bottom), labeled according to Paxinos and Watson (2007), following iontophoretic injection of Lucifer yellow into medium spiny neurons (MSNs). aca, Anterior commissure; ec, external capsule; SA, self-administration.