Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7; Department of Physiology and Pharmacology, Medical Sciences Building, Room 216, University of Western Ontario, London, Ontario, Canada N6A 5C1.
Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7.
Neuroimage. 2015 Jul 1;114:170-84. doi: 10.1016/j.neuroimage.2015.03.082. Epub 2015 Apr 8.
Whether the dorsal striatum (DS) mediates cognitive control or cognitive effort per se in decision-making is unclear given that these effects are highly correlated. As the cognitive control requirements of a neuropsychological task intensify, cognitive effort increases proportionately. We implemented a task that disentangled cognitive control and cognitive effort to specify the particular function DS mediates in decision-making.
Sixteen healthy young adults completed a number Stroop task with simultaneous blood-oxygenation-level-dependent response (BOLD) measurement using functional magnetic resonance imaging. Participants selected the physically larger number of a pair of single-digit integers. Discriminating smaller versus larger physical size differences between a number pair requires greater cognitive effort, but does not require greater cognitive control. We also investigated the effect of conflict between the physical and numerical dimensions of targets (e.g., 2 6). Selections in this incongruent case are more cognitively effortful and require greater cognitive control to suppress responding to the irrelevant dimension. Enhancing cognitive effort or cognitive control demands increases errors and response times. Despite similar behavioural profiles, our aim was to determine whether DS mediates cognitive control or simply indexes cognitive effort, using the same data set.
As expected, behavioural interference effects occurred for both enhanced cognitive control and/or cognitive effort conditions. Despite similar degrees of behavioural interference, DS BOLD signal only correlated with interference arising due to increased cognitive control demands in the incongruent case. DS was not preferentially activated for discriminations of smaller relative to larger physical size differences between number pairs, even when using liberal statistical criteria. However, our incongruent and physical size effects conjointly activated regions related to effortful processing (e.g., anterior cingulate cortex).
We interpret these findings as support for the increasingly accepted notion that DS mediates cognitive control specifically and does not simply index cognitive effort per se.
由于认知控制和认知努力之间高度相关，因此尚不清楚背侧纹状体（DS）在决策中究竟是介导认知控制还是认知努力本身。随着神经心理学任务的认知控制要求的加强，认知努力会相应增加。我们实施了一项任务，该任务可分离认知控制和认知努力，以明确 DS 在决策中所介导的特定功能。
16 名健康的年轻成年人使用功能磁共振成像完成了一项数字斯特鲁普任务，并同时测量了血氧水平依赖性反应（BOLD）。参与者选择一对一位数字中较大的数字。区分数字对之间较小与较大的物理大小差异需要更大的认知努力，但不需要更大的认知控制。我们还研究了目标的物理和数值维度之间冲突的影响（例如，2 6）。在这种不一致的情况下，选择更加费力，需要更大的认知控制来抑制对无关维度的反应。增强认知努力或认知控制需求会增加错误和反应时间。尽管行为表现相似，但我们的目的是使用相同的数据集来确定 DS 是否介导认知控制还是仅仅索引认知努力。
正如预期的那样，在增强认知控制和/或认知努力的条件下都发生了行为干扰效应。尽管行为干扰程度相似，但 DS 的 BOLD 信号仅与不一致情况下由于认知控制需求增加而产生的干扰相关。即使使用宽松的统计标准，DS 也不会优先激活对数字对之间较小的物理大小差异的辨别，而不是较大的物理大小差异。但是，我们的不一致和物理大小效应共同激活了与费力处理相关的区域（例如，前扣带皮层）。
我们将这些发现解释为对越来越多的观点的支持，即 DS 专门介导认知控制，而不仅仅是索引认知努力本身。
