Drug addiction is a chronic, and an easy relapsesable brain disease. The most obvious property is a compulsive drug seeking and taking behavior. Although more than a hundreds years we have realized the serious concequences of addiction and have made lots of progress in understanding the neural mechanisms of addiction, we still can’t cure this brain disease. The purpose of my studies is to elucidate the neural mechanisms of morphine related learning and memory. These findings may help us understand the property of this specific kind of learning and memory, and provide some experimental evidences for possible methods to cure this brain disease. In the first part of this thesis, we reviewed the progress in researches on neural mechanisms of drug addiction. Some popular theory models of addiction focus on different properties of drug addiction. Although each model is reasonable and supported by some evidences, none can explain all the aspects of this complex brain disease. Because more and more evidences indicate that drug addiction is a disease of learning and memory, we specifically introduced the most popular learning and memory model. Firstly, we introduced the neural mechanisms of drug addiction in detail, from the level of molecular to the level of brain system. Furthermore，we showed the relationship between drug addiction and learning and memory. addiction, and obtained some interesting results. The methodologies we used in these studies were pharmacological, brain area lesion, behavioral and transcranial direct current stimulation. In these studies, we found that somatosensory cortices are required for the acquisition of morphine related memory whereas the urge to seek drugs requires the insular cortex. The morphine administration pattern is important for the retention of morphine related memory. Unlike other kinds of memory, the reconsolidation of morphine related memory can not be interrupted by β adrenergic receptor antagonist after retrieval. Inactivation of drug addiction related brain area by transcranial direct current stimulation reduced the cigarette consumption. Our results have demonstrated some of the properties of drug addiction, and obtained some preliminary results in treating nicotine addiction; however, we still can neither fully understand the neural mechanisms, nor can we cure this brain disease. Thus, lots of works need to be done in future.
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