“…However, in place conditioning drug delivery is non-contingent, i.e., drugs are administered by the experimenter. In contrast, self-administration paradigms allow rodents to respond voluntarily for drugs, allowing assessment of drug-seeking and drug-taking behaviors, but require weeks to months of training ( Anker and Carroll, 2010 , Doherty and Frantz, 2012 , Levin et al, 2003 , Levin et al, 2007 , Perry et al, 2007 , Wong et al, 2013 , Wong and Marinelli, 2016 ). Drug studies in adolescent versus adult rats are reviewed further in Section 5.2.2 .…”