Learning is acquisition of information from experiences and memory is retention, storage and retrieval of this information. state-dependent learning is a phenomenon in which the retrieval of newly acquired information is possible only if the subject is in the same sensory context and physiological state as during the encoding phase. The experimental model of this learning type can be made by different drugs. Pharmacological studies in our laboratory and by others have shown that many of drugs including opioids, alcohol, lithium and cholinergic drugs, etc can induce state-dependent learning. These studies usually involve training laboratory animals in simple learning tasks and testing their memory a day or so later. Drugs can be administered to the animals before or after training the learning tasks and their effects on learning would be assessed on the test day. If drug would be administered only before or after training, the animal cannot retrieve the memory in absence of the drug and shows memory impairment. But if the drug was also administered before the test, the animal could retrieve the first day training well and memory impairment will be reversed. Using this simple method of learning not only the bases mechanisms of learning and memory will be elucidated but also but infusions of drugs into different brain areas the involvement of these areas in learning and memory processes will be examined.