酒精依赖中的冲突预期——基于模型的停止信号任务功能磁共振成像研究
Conflict anticipation in alcohol dependence - A model-based fMRI study of stop signal task.
作者信息
Hu Sien, Ide Jaime S, Zhang Sheng, Sinha Rajita, Li Chiang-Shan R
机构信息
Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA.
Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
出版信息
Neuroimage Clin. 2015 Mar 20;8:39-50. doi: 10.1016/j.nicl.2015.03.008. eCollection 2015.
BACKGROUND
Our previous work characterized altered cerebral activations during cognitive control in individuals with alcohol dependence (AD). A hallmark of cognitive control is the ability to anticipate changes and adjust behavior accordingly. Here, we employed a Bayesian model to describe trial-by-trial anticipation of the stop signal and modeled fMRI signals of conflict anticipation in a stop signal task. Our goal is to characterize the neural correlates of conflict anticipation and its relationship to response inhibition and alcohol consumption in AD.
METHODS
Twenty-four AD and 70 age and gender matched healthy control individuals (HC) participated in the study. fMRI data were pre-processed and modeled with SPM8. We modeled fMRI signals at trial onset with individual events parametrically modulated by estimated probability of the stop signal, p(Stop), and compared regional responses to conflict anticipation between AD and HC. To address the link to response inhibition, we regressed whole-brain responses to conflict anticipation against the stop signal reaction time (SSRT).
RESULTS
Compared to HC (54/70), fewer AD (11/24) showed a significant sequential effect - a correlation between p(Stop) and RT during go trials - and the magnitude of sequential effect is diminished, suggesting a deficit in proactive control. Parametric analyses showed decreased learning rate and over-estimated prior mean of the stop signal in AD. In fMRI, both HC and AD responded to p(Stop) in bilateral inferior parietal cortex and anterior pre-supplementary motor area, although the magnitude of response increased in AD. In contrast, HC but not AD showed deactivation of the perigenual anterior cingulate cortex (pgACC). Furthermore, deactivation of the pgACC to increasing p(Stop) is positively correlated with the SSRT in HC but not AD. Recent alcohol consumption is correlated with increased activation of the thalamus and cerebellum in AD during conflict anticipation.
CONCLUSIONS
The current results highlight altered proactive control that may serve as an additional behavioral and neural marker of alcohol dependence.
背景
我们之前的研究描述了酒精依赖（AD）个体在认知控制过程中大脑激活的改变。认知控制的一个标志是能够预测变化并相应地调整行为。在此，我们采用贝叶斯模型来描述对停止信号的逐次试验预测，并对停止信号任务中冲突预测的功能磁共振成像（fMRI）信号进行建模。我们的目标是确定冲突预测的神经关联及其与AD中反应抑制和酒精消耗的关系。
方法
24名AD患者和70名年龄及性别匹配的健康对照个体（HC）参与了该研究。fMRI数据使用SPM8进行预处理和建模。我们在试验开始时用由停止信号的估计概率p(Stop)参数调制的个体事件对fMRI信号进行建模，并比较AD和HC之间对冲突预测的区域反应。为了探讨与反应抑制的联系，我们将全脑对冲突预测的反应与停止信号反应时间（SSRT）进行回归分析。
结果
与HC（54/70）相比，较少的AD患者（11/24）表现出显著的序列效应——即进行试验期间p(Stop)与反应时间（RT）之间的相关性——并且序列效应的幅度减小，表明主动控制存在缺陷。参数分析显示AD患者的学习率降低且对停止信号的先验均值估计过高。在fMRI中，HC和AD在双侧下顶叶皮质和前辅助运动区均对p(Stop)有反应，尽管AD中的反应幅度增加。相反，HC而非AD表现出膝周前扣带回皮质（pgACC）的失活。此外，在HC中pgACC随p(Stop)增加的失活与SSRT呈正相关，而在AD中则不然。近期饮酒与AD患者在冲突预测期间丘脑和小脑的激活增加相关。
结论
当前结果突出了主动控制的改变，这可能作为酒精依赖的额外行为和神经标志物。
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