Levichkina Ekaterina, Saalmann Yuri B, Vidyasagar Trichur R
Department of Optometry & Vision Sciences, University of Melbourne, Melbourne, Australia.
Institute for Information Transmission Problems RAS, Moscow, Russia.
Physiol Rep. 2017 Mar;5(5). doi: 10.14814/phy2.13136.
Primate posterior parietal cortex (PPC) is known to be involved in controlling spatial attention. Neurons in one part of the PPC, the lateral intraparietal area (LIP), show enhanced responses to objects at attended locations. Although many are selective for object features, such as the orientation of a visual stimulus, it is not clear how LIP circuits integrate feature-selective information when providing attentional feedback about behaviorally relevant locations to the visual cortex. We studied the relationship between object feature and spatial attention properties of LIP cells in two macaques by measuring the cells' orientation selectivity and the degree of attentional enhancement while performing a delayed match-to-sample task. Monkeys had to match both the location and orientation of two visual gratings presented separately in time. We found a wide range in orientation selectivity and degree of attentional enhancement among LIP neurons. However, cells with significant attentional enhancement had much less orientation selectivity in their response than cells which showed no significant modulation by attention. Additionally, orientation-selective cells showed working memory activity for their preferred orientation, whereas cells showing attentional enhancement also synchronized with local neuronal activity. These results are consistent with models of selective attention incorporating two stages, where an initial feature-selective process guides a second stage of focal spatial attention. We suggest that LIP contributes to both stages, where the first stage involves orientation-selective LIP cells that support working memory of the relevant feature, and the second stage involves attention-enhanced LIP cells that synchronize to provide feedback on spatial priorities.
已知灵长类动物的后顶叶皮质（PPC）参与控制空间注意力。PPC的一个区域，即外侧顶内区（LIP）中的神经元，对被关注位置的物体表现出增强的反应。尽管许多神经元对物体特征具有选择性，例如视觉刺激的方向，但尚不清楚LIP回路在向视觉皮层提供有关行为相关位置的注意力反馈时，是如何整合特征选择性信息的。我们通过在执行延迟样本匹配任务时测量细胞的方向选择性和注意力增强程度，研究了两只猕猴中LIP细胞的物体特征与空间注意力特性之间的关系。猴子必须匹配两个在时间上分开呈现的视觉光栅的位置和方向。我们发现LIP神经元的方向选择性和注意力增强程度存在很大差异。然而，与未受注意力显著调制的细胞相比，具有显著注意力增强的细胞在反应中的方向选择性要小得多。此外，方向选择性细胞对其偏好方向表现出工作记忆活动，而表现出注意力增强的细胞也与局部神经元活动同步。这些结果与包含两个阶段的选择性注意模型一致，其中初始的特征选择性过程引导焦点空间注意的第二阶段。我们认为LIP对两个阶段都有贡献，第一阶段涉及支持相关特征工作记忆的方向选择性LIP细胞，第二阶段涉及同步以提供空间优先级反馈的注意力增强LIP细胞。
