Voon V, Baek K, Enander J, Worbe Y, Morris L S, Harrison N A, Robbins T W, Rück C, Daw N
Department of Psychiatry, Addenbrookes Hospital, University of Cambridge, Cambridge, UK.
Department of Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK.
Transl Psychiatry. 2015 Nov 3;5(11):e670. doi: 10.1038/tp.2015.165.
Our decisions are based on parallel and competing systems of goal-directed and habitual learning, systems which can be impaired in pathological behaviours. Here we focus on the influence of motivation and compare reward and loss outcomes in subjects with obsessive-compulsive disorder (OCD) on model-based goal-directed and model-free habitual behaviours using the two-step task. We further investigate the relationship with acquisition learning using a one-step probabilistic learning task. Forty-eight OCD subjects and 96 healthy volunteers were tested on a reward and 30 OCD subjects and 53 healthy volunteers on the loss version of the two-step task. Thirty-six OCD subjects and 72 healthy volunteers were also tested on a one-step reversal task. OCD subjects compared with healthy volunteers were less goal oriented (model-based) and more habitual (model-free) to reward outcomes with a shift towards greater model-based and lower habitual choices to loss outcomes. OCD subjects also had enhanced acquisition learning to loss outcomes on the one-step task, which correlated with goal-directed learning in the two-step task. OCD subjects had greater stay behaviours or perseveration in the one-step task irrespective of outcome. Compulsion severity was correlated with habitual learning in the reward condition. Obsession severity was correlated with greater switching after loss outcomes. In healthy volunteers, we further show that greater reward magnitudes are associated with a shift towards greater goal-directed learning further emphasizing the role of outcome salience. Our results highlight an important influence of motivation on learning processes in OCD and suggest that distinct clinical strategies based on valence may be warranted.
我们的决策基于目标导向和习惯学习这两个并行且相互竞争的系统，而这些系统在病理行为中可能会受损。在此，我们聚焦于动机的影响，并使用两步任务比较强迫症（OCD）患者在基于模型的目标导向行为和无模型的习惯行为中对奖励和损失结果的反应。我们还使用一步概率学习任务进一步研究与习得性学习的关系。48名强迫症患者和96名健康志愿者接受了两步任务奖励版本的测试，30名强迫症患者和53名健康志愿者接受了两步任务损失版本的测试。36名强迫症患者和72名健康志愿者还接受了一步反转任务的测试。与健康志愿者相比，强迫症患者在奖励结果方面目标导向性（基于模型）较低，习惯（无模型）性较强，而在损失结果方面则向更多基于模型和更少习惯选择转变。在一步任务中，强迫症患者对损失结果的习得性学习也增强，这与两步任务中的目标导向学习相关。无论结果如何，强迫症患者在一步任务中都有更强的停留行为或固执行为。强迫症状严重程度与奖励条件下的习惯学习相关。强迫观念严重程度与损失结果后的更多转换相关。在健康志愿者中，我们进一步表明，更大的奖励幅度与向更多目标导向学习的转变相关，这进一步强调了结果显著性的作用。我们的结果突出了动机对强迫症学习过程的重要影响，并表明基于效价的不同临床策略可能是必要的。
