| 其他摘要 | Drug addiction is a problem of complex, compulsive drug administration. It is defined specifically as a compulsive pattern of drug-seeking and drug-taking behavior. That is, addicts loss of control in drug seeking and taking behavior. Accumulated studies have demonstrated that repeated exposure to certain drugs can produce deleterious sequelae, especially cognitive impairments, cognitive biases and emotion dysfunction, which may be the reason for drug abuse and relapse. The purpose of the present study is to further investigate the effects of drug abuse on cognition and emotion as well as its underlying mechanisms. To this end, we used a series of neuropsychological paradigms, including simple reaction time, choice reaction time, rapid serial visual presentation (RSVP) and right-left discrimination, to study the effects of opioids abuse on cognitive functions (such as information processing, the temporal domain of attention and the ability of right-left discrimination) and emotion and whether such drug effects, if exist, are related to gender, the duration of withdrawal, the duration of abuse and the age when drug abuse began. We found that 1) heroin dependent patients (HDPs) performed poorer than controls in all the tests. 2) there were cognitive biases in the processing of addiction-related stimuli: in the RSVP task, the attentional blink in the HDPs was exaggerated in neutral and negative words but not in addiction associated words compared with controls. 3) The experience of emotions may be significantly altered in HDPs: they showed lower arousal rating of negative words than neutral and addiction-associated words, whereas controls performed similarly in arousal rating cross the three kinds of words. Also, their ratings of negative words were lower compared with controls. On the other hand, in the RSVP task, there were smaller affective effects on the attentional blink in HDPs than controls. 4) The impairment in cognitive functions and cognitive biases are gender related: heroin dependent females demonstrated greater performance deficits and cognitive biases than males. 5) The effects of the duration of withdrawal, duration of abuse and the age that begin drug abuse have different effects among the tasks. This part of study revealed, in a systematic way, the characteristics of drug abuse effects on cognition and emotion. To further explore the mechanism of the impairments in cognitive functions and emotion, we recorded Electroencephalogram (EEG) in the orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC) during the development of morphine dependence, tolerance and withdrawal in rhesus monkeys. Also, we studied the response of the amygdala to effective stimuli in human by using functional magnetic resonance imaging (fMRI). We found that morphine decreased EEG power in all frequency bands in short period after injection in both the OFC and DLPFC in monkeys. The decrease in gamma power lasted for 12 hours after morphine injection. It provided a possible neural mechanism underlying the cognitive deficits observed in addicts. By using fMRI, we found that the percent signal changes were significantly lower in HDPs relative to normal controls in the left amygdala, especially for the positive pictures, suggesting a possible cause of abnormal emotion with drug abuse. Our results showed one possible explanation of the dysfunction of cognition and emotion in addicts and provided the further evidence for the role played by the prefrontal cortex and amygdala in drug abuse. |
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