Department of Neuroscience,
Department of Psychiatry and Human Behavior.
J Neurosci. 2019 Feb 20;39(8):1471-1483. doi: 10.1523/JNEUROSCI.1060-18.2018. Epub 2018 Dec 21.
An essential human skill is our capacity to monitor and execute a sequence of tasks in the service of an overarching goal. Such a sequence can be as mundane as making a cup of coffee or as complex as flying a fighter plane. Previously, we showed that, during sequential control, the rostrolateral prefrontal cortex (RLPFC) exhibits activation that ramps steadily through the sequence and is necessary for sequential task execution using fMRI in humans (Desrochers et al., 2015). It remains unknown what computations may underlie this ramping dynamic. Across two independent fMRI experiments, we manipulated three features that were unique to the sequential control task to determine whether and how they modulated ramping activity in the RLPFC: (1) sequence position uncertainty, (2) sequential monitoring without external position cues (i.e., from memory), and (3) sequential monitoring without multilevel decision making (i.e., task execution). We replicated the ramping activation in RLPFC and found it to be remarkably robust regardless of the level of task abstraction or engagement of memory functions. Therefore, these results both replicate and extend previous findings regarding the function of the RLPFC. They suggest that sequential control processes are integral to the dynamics of RLPFC activity. Advancing knowledge of the neural bases of sequential control is crucial for our understanding of the sequential processes that are necessary for daily living. We perform sequences of tasks every day, but little is known about how they are controlled in the brain. Previously we found that ramping activity in the rostrolateral prefrontal cortex (RLPFC) was necessary to perform a sequence of tasks. We designed two independent fMRI experiments in human participants to determine which features of the previous sequential task potentially engaged ramping in the RLPFC. We found that any demand to monitor a sequence of state transitions consistently elicited ramping in the RLPFC, regardless of the level of the decisions made at each step in the sequence or engagement of memory functions. These results provide a framework for understanding RLPFC function during sequential control, and consequently, daily life.
一项重要的人类技能是我们监控和执行一系列任务以实现总体目标的能力。这样的序列可以像泡一杯咖啡一样平凡，也可以像驾驶战斗机一样复杂。以前，我们通过 fMRI 研究发现，在序列控制过程中，额侧前扣带回皮层（RLPFC）的激活会逐渐增加，并在人类中执行序列任务时是必需的（Desrochers 等人，2015 年）。目前尚不清楚这种逐渐增加的动态可能基于什么计算。在两个独立的 fMRI 实验中，我们操纵了序列控制任务所特有的三个特征，以确定它们是否以及如何调节 RLPFC 中的逐渐增加的活动：（1）序列位置不确定性，（2）无外部位置提示（即来自记忆）的序列监控，以及（3）无多层次决策（即任务执行）的序列监控。我们复制了 RLPFC 中的逐渐增加的激活，发现无论任务抽象程度或记忆功能的参与程度如何，这种激活都非常稳健。因此，这些结果既复制又扩展了以前关于 RLPFC 功能的发现。它们表明，序列控制过程是 RLPFC 活动动态的组成部分。了解序列控制的神经基础对于我们理解日常生活中所需的序列过程至关重要。我们每天都会执行一系列任务，但对它们在大脑中的控制方式知之甚少。以前我们发现，额侧前扣带回皮层（RLPFC）的逐渐增加的活动对于执行一系列任务是必需的。我们在人类参与者中设计了两个独立的 fMRI 实验，以确定以前的序列任务的哪些特征可能在 RLPFC 中引发了逐渐增加的活动。我们发现，无论在序列中的每个步骤中做出的决策水平或记忆功能的参与如何，对监控状态转换序列的任何需求都会在 RLPFC 中引起逐渐增加的活动。这些结果为理解 RLPFC 在序列控制过程中的功能提供了一个框架，从而理解日常生活。
