Gaál Zsófia A, Czigler István
Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
Front Hum Neurosci. 2015 Apr 13;9:177. doi: 10.3389/fnhum.2015.00177. eCollection 2015.
We studied cognitive and age-related changes in three task-switching (TS) paradigms: (1) informatively cued TS with go stimuli, (2) informatively cued TS with go and nogo stimuli, (3) non-informatively cued TS with go and nogo stimuli. This design allowed a direct comparison, how informative and non-informative cues influenced preparatory processes, and how nogo stimuli changed the context of the paradigm and cognitive processing in different aging groups. Beside the behavioral measures [reaction time (RT), error rate], event-related potentials (ERPs) were registered to the cue and target stimuli in young (N = 39, mean age = 21.6 ± 1.6 years) and older (N = 40, mean age = 65.7 ± 3.2 years) adults. The results provide evidence for declining performance in the older group: they had slower RT, less hits, more erroneous responses, higher mixing costs and decreased amplitude of ERP components than the participants of the younger group. In the task without the nogo stimuli young adults kept the previous task-set active that could be seen in shorter RT and larger amplitude of cue-locked late positivity (P3b) in task repeat (TR) trials compared to task switch trials. If both go and nogo stimuli were presented, similar RTs and P3b amplitudes appeared in the TR and TS trials. In the complex task situations older adults did not evolve an appropriate task representation and task preparation, as indicated by the lack of cue-locked P3b, CNV, and target-locked P3b. We conclude that young participants developed explicit representation of task structures, but the presence of nogo stimuli had marked effects on such representation. On the other hand, older people used only implicit control strategy to solve the task, hence the basic difference between the age groups was their strategy of task execution.
我们研究了三种任务切换（TS）范式中与认知和年龄相关的变化：（1）有提示信息的go刺激的TS范式；（2）有提示信息的go和nogo刺激的TS范式；（3）无提示信息的go和nogo刺激的TS范式。这种设计使得我们能够直接比较提示信息和无提示信息如何影响准备过程，以及nogo刺激如何改变不同年龄组的范式背景和认知加工。除行为测量指标[反应时（RT）、错误率]外，我们还记录了年轻成年人（N = 39，平均年龄 = 21.6 ± 1.6岁）和年长成年人（N = 40，平均年龄 = 65.7 ± 3.2岁）对提示和目标刺激的事件相关电位（ERP）。结果表明年长组的表现有所下降：与年轻组参与者相比，他们的反应时较慢、命中率较低、错误反应较多、混合成本较高且ERP成分的波幅减小。在没有nogo刺激的任务中，年轻成年人保持之前激活的任务集，这可以从任务重复（TR）试验中比任务切换试验更短的反应时和提示锁定晚期正波（P3b）更大的波幅中看出。如果同时呈现go和nogo刺激，TR和TS试验中的反应时和P3b波幅相似。在复杂任务情境中，年长成年人没有形成适当的任务表征和任务准备，这表现为缺乏提示锁定P3b、关联性负变（CNV）和目标锁定P3b。我们得出结论，年轻参与者形成了明确的任务结构表征，但nogo刺激的存在对这种表征有显著影响。另一方面，年长者仅使用隐性控制策略来解决任务，因此年龄组之间的根本差异在于他们的任务执行策略。
