Department of Health Sciences, University of Milan , Milan , Italy ; Applied Research Unit for Cognitive and Psychological Science, European Institute of Oncology , Milan , Italy.
Library, European Institute of Oncology , Milan , Italy.
Front Hum Neurosci. 2014 Aug 27;8:661. doi: 10.3389/fnhum.2014.00661. eCollection 2014.
Previous neurobiological and neuropsychological investigations have shown that risk-taking behaviors and addictions share many structural and functional aspects. In particular, both are characterized by an irresistible need to obtain immediate rewards and by specific alterations in brain circuits responsible for such behaviors. In this study, we used transcranial direct-current stimulation over the dorsolateral prefrontal cortex (DLPFC) of two samples of subjects (18 dependent cocaine users and 18 control subjects) to investigate the effects of left and right cortical excitability on two risk tasks: (1) the balloon analog risk task (BART) and (2) the game of dice task (GDT). All subjects randomly received a left anodal/right cathodal stimulation (LAn+), a right anodal/left cathodal stimulation (RAn+), and a sham (placebo) stimulation each run at least 48 h apart. Participants were asked to perform the BART and the GDT immediately before and after each stimulation. Our results reveal that the activation of the DLPFC (left and right) results in a reduction of risky behaviors at the BART task both in controls subjects and cocaine dependent users. The effect of tDCS on GDT, instead, is more complex. Cocaine users increased safe behavior after right DLPFC anodal stimulation, while risk-taking behavior increased after left DLPFC anodal stimulation. Control subjects' performance was only affected by the anodal stimulation of the right DLPFC, resulting in an increase of safe bets. These results support the hypothesis that excessive risk propensity in dependent cocaine users might be due to a hypoactivation of the right DLPFC and an unbalance interhemispheric interaction. In conclusion, since risky decision-making seems to be, at least in part, responsible for maintenance and relapse of addiction, we argue that a neuromodulation-based approach could represent a valuable adjunct in the clinical treatment of addiction.
先前的神经生物学和神经心理学研究表明，冒险行为和成瘾具有许多结构和功能方面的共同之处。特别是，两者都表现为对获得即时奖励的不可抗拒的需求，以及对负责此类行为的大脑回路的特定改变。在这项研究中，我们使用经颅直流电刺激（tDCS）对两个样本的受试者（18 名依赖可卡因的使用者和 18 名对照受试者）的背外侧前额叶皮层（DLPFC）进行刺激，以研究左、右皮质兴奋性对两种风险任务的影响：（1）气球模拟风险任务（BART）和（2）掷骰子游戏任务（GDT）。所有受试者在至少相隔 48 小时的情况下，每个实验运行时分别接受左侧阳极/右侧阴极刺激（LAn+）、右侧阳极/左侧阴极刺激（RAn+）和假刺激（安慰剂）。受试者被要求在每次刺激前后立即进行 BART 和 GDT。我们的结果表明，DLPFC 的激活（左侧和右侧）会导致 BART 任务中冒险行为的减少，无论是在对照受试者还是可卡因依赖使用者中。然而，tDCS 对 GDT 的影响更为复杂。右 DLPFC 阳极刺激后，可卡因使用者增加了安全行为，而左 DLPFC 阳极刺激后则增加了冒险行为。控制组受试者的表现仅受到右 DLPFC 阳极刺激的影响，导致安全投注增加。这些结果支持这样一种假设，即依赖可卡因使用者的过度冒险倾向可能是由于右 DLPFC 的低激活和半球间相互作用的不平衡。总之，由于冒险决策似乎至少在一定程度上是成瘾维持和复发的原因，我们认为基于神经调节的方法可能是成瘾临床治疗的一个有价值的辅助手段。
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