Performance deterioration over time, or time-on-task (TOT) effects, can be observed across a variety of tasks, but little attention has been paid to how TOT-related brain activity may differ based on task pacing and cognitive demands. Here, we employ a set of three closely related tasks to investigate the effect of these variables on fMRI activation and connectivity. When participants dictated the pace of their own responses, activation and network connectivity within the dorsal attention network (DAN) increased over short time scales (~2-3 min), a phenomenon that was not observed when participants had no control over their pace of work. Reaction time slowing was also the most pronounced in this self-paced task. In contrast, TOT-related changes in default-mode network (DMN) activity and connectivity, DAN-DMN anti-correlations, and pupil diameter did not differ based on pacing or task instructions. Over a longer (~10 min) time scale, task-positive activation and connectivity decreased in all paradigms, in agreement with older findings. These results highlight dynamic patterns of resource allocation that have not previously been observed in fMRI experiments, and speak to the idea that the brain may strategically allocate resources depending on the task at hand and the time scale of work.

中文翻译：

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调整自己的步调：神经激活和连接性随时间的变化因任务类型和步调而异。

可以在各种任务中观察到随着时间的推移性能的下降或任务完成时间（TOT）的影响，但是很少有人关注基于TOT的大脑活动如何根据任务节奏和认知需求而有所不同。在这里，我们采用一组三个紧密相关的任务来研究这些变量对功能磁共振成像激活和连接性的影响。当参与者决定自己的反应速度时，背侧注意力网络（DAN）内的激活和网络连接性会在较短的时间内（约2-3分钟）增加，当参与者无法控制自己的反应速度时，就不会观察到这种现象。工作。反应速度减慢也是这项自定进度任务中最明显的。相比之下，默认模式网络（DMN）活动和连接，DAN-DMN反相关，TOT相关的变化，和瞳孔直径根据起搏或任务说明而不同。在较长的时间范围内（〜10分钟），所有范例中的任务阳性激活和连接性均下降，这与较早的发现一致。这些结果突出了功能分配的动态模式，以前在功能磁共振成像实验中还没有观察到这些，并且表明了大脑可以根据手头的任务和工作时间规模来战略性地分配资源的想法。