Crone Eveline A, Donohue Sarah E, Honomichl Ryan, Wendelken Carter, Bunge Silvia A
Center for Mind and Brain, University of California, Davis, California 95616, USA.
J Neurosci. 2006 Oct 25;26(43):11239-47. doi: 10.1523/JNEUROSCI.2165-06.2006.
During development, children improve at retrieving and using rules to guide their behavior and at flexibly switching between these rules. In this study, we used functional magnetic resonance imaging to examine the changes in brain function associated with developmental changes in flexible rule use. Three age groups (8-12, 13-17, and 18-25 years) performed a task in which they were cued to respond to target stimuli on the basis of simple task rules. Bivalent target stimuli were associated with different responses, depending on the rule, whereas univalent target stimuli were associated with fixed responses. The comparison of bivalent and univalent trials enabled the identification of regions modulated by demands on rule representation. The comparison of rule-switch and rule-repetition trials enabled the identification of regions involved in rule switching. We have used this task previously in adults and have shown that ventrolateral prefrontal cortex (VLPFC) and the (pre)-supplementary motor area (pre-SMA/SMA) have dissociable roles in task-switching, such that VLPFC is associated most closely with rule representation, and pre-SMA/SMA is associated with suppression of the previous task set (Crone et al., 2006a). Based on behavioral data in children (Crone et al., 2004), we had predicted that regions associated with task-set suppression would show mature patterns of activation earlier in development than regions associated with rule representation. Indeed, we found an adult-like pattern of activation in pre-SMA/SMA by adolescence, whereas the pattern of VLPFC activation differed among children, adolescents, and adults. These findings suggest that two components of task-switching--rule retrieval and task-set suppression--follow distinct neurodevelopmental trajectories.
在发育过程中，儿童在检索和运用规则以指导其行为方面有所进步，并且能够灵活地在这些规则之间进行切换。在本研究中，我们使用功能磁共振成像来检查与灵活规则运用的发育变化相关的脑功能变化。三个年龄组（8 - 12岁、13 - 17岁和18 - 25岁）执行了一项任务，在该任务中，他们根据简单的任务规则被提示对目标刺激做出反应。二价目标刺激根据规则与不同的反应相关联，而单价目标刺激与固定反应相关联。对二价和单价试验的比较能够识别受规则表征需求调节的区域。对规则切换和规则重复试验的比较能够识别参与规则切换的区域。我们之前在成年人中使用过这个任务，并表明腹外侧前额叶皮层（VLPFC）和（前）辅助运动区（pre - SMA/SMA）在任务切换中具有可分离的作用，即VLPFC与规则表征最密切相关，而pre - SMA/SMA与抑制先前的任务集相关（Crone等人，2006a）。基于儿童的行为数据（Crone等人，2004），我们预测与任务集抑制相关的区域在发育中比与规则表征相关的区域更早地表现出成熟的激活模式。事实上，我们发现到青春期时pre - SMA/SMA出现了类似成年人的激活模式，而VLPFC的激活模式在儿童、青少年和成年人中有所不同。这些发现表明任务切换的两个组成部分——规则检索和任务集抑制——遵循不同的神经发育轨迹。
