Skip to main content
. Author manuscript; available in PMC: 2010 Feb 17.
Published in final edited form as: Psychopharmacology (Berl). 2009 Aug 13;207(1):99. doi: 10.1007/s00213-009-1637-x

Figure 1.

Figure 1

Dose-response functions for self-administration of cocaine (Coc, bold solid line, squares), nicotine (Nic, thin solid line, triangles), and cocaine mixed with various concentrations of nicotine (hatched lines) under a progressive-ratio schedule of reinforcement. Nicotine concentrations were mixed according to dose per injection. Each point is the mean value for two test sessions at each dose or combination, vertical lines are the range (S.E.M.). Numbers a the top of each graph are the monkey numbers.