Department of Biosciences and Informatics, Keio University, Yokohama 223-0061, Japan.
Research Center for Brain Communication, Kochi University of Technology, Kami 782-8502, Japan.
J Neurosci. 2021 Mar 10;41(10):2197-2213. doi: 10.1523/JNEUROSCI.2096-20.2021. Epub 2021 Jan 19.
Flexible adaptation to changing environments is a representative executive control function implicated in the frontoparietal network that requires appropriate extraction of goal-relevant information through perception of the external environment. It remains unclear, however, how the flexibility is achieved under situations where goal-relevant information is uncertain. To address this issue, the current study examined neural mechanisms for task switching in which task-relevant information involved perceptual uncertainty. Twenty-eight human participants of both sexes alternated behavioral tasks in which they judged motion direction or color of visually presented colored dot stimuli that moved randomly. Task switching was associated with frontoparietal regions in the left hemisphere, and perception of ambiguous stimuli involved contralateral homologous frontoparietal regions. On the other hand, in stimulus-modality-dependent occipitotemporal regions, task coding information was increased during task switching. Effective connectivity analysis revealed that the frontal regions signaled toward the modality-dependent occipitotemporal regions when a relevant stimulus was more ambiguous, whereas the occipitotemporal regions signaled toward the frontal regions when the stimulus was more distinctive. These results suggest that complementary prefrontal mechanisms in the left and right hemispheres help to achieve a behavioral goal when the external environment involves perceptual uncertainty. In our daily life, environmental information to achieve a goal is not always certain, but we make judgments in such situations, and change our behavior accordingly. This study examined how the flexibility of behavior is achieved in a situation where goal-relevant information involves perceptual uncertainty. fMRI revealed that the lateral prefrontal cortex (PFC) in the left hemisphere is associated with behavioral flexibility, and the perception of ambiguous stimuli involves the PFC in the right hemisphere. These bilateral PFC signaled to stimulus-modality-dependent occipitotemporal regions, depending on perceptual uncertainty and the task to be performed. These top-down signals supplement task coding in the occipitotemporal regions, and highlight interhemispheric prefrontal mechanisms involved in executive control and perceptual decision-making.
灵活适应不断变化的环境是一种代表性的执行控制功能，涉及额顶网络，需要通过感知外部环境来适当提取与目标相关的信息。然而，在目标相关信息不确定的情况下，这种灵活性是如何实现的，目前还不清楚。为了解决这个问题，本研究考察了任务转换的神经机制，其中与任务相关的信息涉及知觉不确定性。28 名男女参与者在行为任务之间交替进行，他们判断视觉呈现的彩色点刺激的运动方向或颜色，这些刺激随机移动。任务转换与左半球的额顶区域有关，而对模糊刺激的感知涉及对侧同源的额顶区域。另一方面，在刺激模态相关的枕颞区域，任务转换时任务编码信息增加。有效连通性分析表明，当相关刺激更模糊时，额区向模态相关的枕颞区发出信号，而当刺激更独特时，枕颞区向额区发出信号。这些结果表明，当外部环境涉及知觉不确定性时，左右半球互补的前额叶机制有助于实现行为目标。在我们的日常生活中，实现目标的环境信息并不总是确定的，但我们在这种情况下做出判断，并相应地改变我们的行为。本研究考察了在目标相关信息涉及知觉不确定性的情况下，行为的灵活性是如何实现的。fMRI 显示，左半球的外侧前额叶皮层（PFC）与行为灵活性有关，而对模糊刺激的感知涉及右半球的 PFC。这些双侧 PFC 根据知觉不确定性和要执行的任务向刺激模态相关的枕颞区域发出信号。这些自上而下的信号补充了枕颞区域的任务编码，并突出了执行控制和知觉决策涉及的半球间前额叶机制。
