Department of Psychology, University of Calgary, Calgary AB T2N 1N4, Canada.
Hotchkiss Brain Institute, University of Calgary, Calgary AB T2N 4N1, Canada.
Cereb Cortex. 2021 Jan 5;31(2):873-883. doi: 10.1093/cercor/bhaa262.
Decades of electrophysiological research on top-down control converge on the role of the lateral frontal cortex in facilitating attention to behaviorally relevant external inputs. However, the involvement of frontal cortex in the top-down control of attention directed to the external versus internal environment remains poorly understood. To address this, we recorded intracranial electrocorticography while subjects directed their attention externally to tones and responded to infrequent target tones, or internally to their own thoughts while ignoring the tones. Our analyses focused on frontal and temporal cortices. We first computed the target effect, as indexed by the difference in high frequency activity (70-150 Hz) between target and standard tones. Importantly, we then compared the target effect between external and internal attention, reflecting a top-down attentional effect elicited by task demands, in each region of interest. Both frontal and temporal cortices showed target effects during external and internal attention, suggesting this effect is present irrespective of attention states. However, only the frontal cortex showed an enhanced target effect during external relative to internal attention. These findings provide electrophysiological evidence for top-down attentional modulation in the lateral frontal cortex, revealing preferential engagement with external attention.
几十年来，对自上而下控制的电生理学研究集中在外侧额叶皮层在促进对外界行为相关输入的注意力上的作用。然而，额叶皮层在对外界和内部环境的注意力的自上而下控制中的参与仍然知之甚少。为了解决这个问题，我们在受试者将注意力指向外部声音并对罕见的目标声音做出反应，或内部指向自己的想法而忽略声音时，记录了颅内脑电图。我们的分析集中在额叶和颞叶皮层。我们首先计算了目标效应，该效应由目标和标准声音之间的高频活动（70-150 Hz）差异来表示。重要的是，然后我们在每个感兴趣的区域中比较了外部和内部注意力之间的目标效应，反映了由任务需求引起的自上而下的注意力效应。额叶和颞叶皮层在外部和内部注意力期间都表现出目标效应，这表明无论注意力状态如何，这种效应都存在。然而，只有额叶皮层在外部注意力相对于内部注意力时表现出增强的目标效应。这些发现为外侧额叶皮层中的自上而下的注意力调制提供了电生理学证据，揭示了对外界注意力的优先参与。
