FIGURE 3.

Pharmacological stimulation of the LPO promotes sucrose seeking, but does not change sucrose self-administration. (A) Timeline of behavioral procedures. SA, self-administration; FR, fixed ratio (number of responses required to obtain one reward delivery, depicted with pink lines). Pellets: number of pellets obtained per reward delivery, depicted with pink lines. (B) Location of LPO injections for aCSF (gray) and bicuculline (Bic, purple). (C) Sucrose self-administration behavior. Both groups acquired sucrose self-administration and there was no difference between groups across self-administration or over the last 3 days of self-administration (SA Pre). Rats updated responding with changes in FR schedule and number of rewards per delivery. (D) Self-administration test (SA Test). Stimulating the LPO with bicuculline did not change active hole or inactive hole responding relative to aCSF controls. (E) Extinction behavior. Both groups extinguished responding on the previously active hole. There was no difference between groups across extinction or over the last 3 days of extinction (Ext Pre). (F) Extinction test (Ext Test). Stimulating the LPO with bicuculline reinstated sucrose seeking behavior, observed as increased responding on the previously active hole (HSD, ^∗∗P < 0.01) but not the inactive hole (HSD, P = 1.00). Symbols are mean ± SEM for each group; lines are individual subjects. See main text for detailed statistics.