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12、成瘾模型中,奖赏、抑制控制、驱动和学习记忆四回路模型的研

更新时间:2015-08-01 14:20 点击:
  

 本研究针对海洛因依赖者与正常人的静息态数据,采用模式分类方法刻画两组人大脑功能差异。申请人针对21位海洛因依赖者和23位正常被试的静息态数据对比分析发现,存在差异的大脑区域与Volkow提出的成瘾四回路模型(奖赏、驱动、记忆和抑制控制)基本一致:Caudate属于奖赏回路;MPFC和ACC属于抑制控制回路;OFC属于驱动回路;Putamen,AMY和HIPP属于学习和记忆回路(图1所示)。Granger因果有效连接度分析发现:MPFC和ACC的抑制控制能力降低了;AMY和HIPP的学习和记忆能力压制了上述的抑制控制能力,因为他们脑海里对海洛因的深刻印象刺激他们想去吸食;OFC对Putamen的驱动能力增强了,对它产生了强烈的驱动作用;而Caudate和Putamen作为奖赏的主要核团被其它区域异常驱动,从而促使海洛因患者吸食(图2所示)。此外,我们根据上述研究中核团间相互因果作用关系的改变,提出了海洛因成瘾四回路间的模型,是对Volkow提出的成瘾四回路模型的一个细化和完善,如图3所示。上述针对回路内部核团以及回路之间的相互因果作用关系的研究。

 
Granger Causality Revealing a Dominant Role of Memory Circuit in Chronic Opioid Dependence 
Resting-state MRI has uncovered abnormal functional connectivity in heroin dependent individuals. However, it remains unclear how brain regions implicated in addictions are related, change during baseline state without conditioned cues in heroin dependent individuals during opioid maintenance treatment (HDIs-OMT). Previous connectivity analysis permits measurement of the strength of correlated activity between brain regions but lacks the ability to infer directional neural interactions. In the current study, we employed Granger causality analysis to investigate directional causal influences among the brain circuits in HDIs-OMT versus non-opioid users. The results revealed a decreased baseline-activity in the caudate nucleus and weakened driving forces to the Reward circuit. The inhibitory control elicited by the anterior cingulate cortex (ACC) and medial prefrontal cortex also showed a reducing trend. Conversely, HDIs-OMT exhibited greater learning-memory effects than controls in the hippocampus and amygdala, which might push the Memory circuit to override the Control circuit at the ACC and drive the putamen for learned habit in HDIs-OMT. Learning-memory and inhibitory control effects may contribute jointly and form a basis for relapse risk even after a period of heroin abstinence. Sustained neural effect of prior opioid abuse including hyperactivation in the Memory circuit and impairment in the Control circuit offer additional support for Memory circuitry in relapse, and may help redefine targets for treatment.   
                        
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