Self-administration is, in its medical sense, the process of a subject administering a pharmacological substance to themself. A clinical example of this is the subcutaneous "self-injection" of insulin by a diabetic patient. In animal experimentation, self-administration is a form of operant conditioning where the reward is a drug. This drug can be administered remotely through an implanted intravenous line or an intracerebroventricular injection. Self-administration of putatively addictive drugs is considered one of the most valid experimental models to investigate drug-seeking and drug-taking behavior. The higher the frequency with which a test animal emits the operant behavior, the more rewarding (and addictive), the test substance is considered. Self-administration of addictive drugs has been studied using humans, non-human primates, mice, invertebrates such as ants, and, most commonly, rats. Self-administration of heroin and cocaine is used to screen drugs for possible effects in reducing drug-taking behavior, especially reinstatement of drug-seeking after extinction. Drugs with this effect may be useful for treating people with drug addiction by helping them establish abstinence or reducing their probability of relapsing to substance use after a period of abstinence. In a prominent model of self-administration developed by George Koob, rats are allowed to self-administer cocaine for either 1 hour each day (short access) or 6 hours each day (long access). Those animals who are allowed to self-administer for 6 hours a day show behavior that is thought to resemble cocaine dependence, such as an escalation of the total dose taken during each session and an increase in the dose taken when cocaine is first made available. Background The "self-administration" behavioral paradigm serves as an animal behavioral model of the human pathology of addiction. During the task, animal subjects are operant conditioned to perform one action, typically a lever press, in order to receive a drug. Reinforcement (through the use of the drug) occurs contingent upon the subject performing the desired behavior. Drug dosing in self-administration studies is response-dependent. This is an important element of creating a disease model of drug addiction in humans because response-independent drug administration is associated with increased toxicity and different neurobiological, neurochemical, and behavioral effects. In summary, the effects of response-dependent drug dosing greatly differ from response-independent drug dosing and self-administration studies appropriately capture this distinction. History As far back as the mid-20th century, researchers have investigated animals’ drive to consume addictive substances in order to better understand human addictive processes. Spragg was one