Data from: Pop-out search instigates beta-gated feature selectivity enhancement across V4 layers

Visual search is a work-horse for investigating how attention interacts with processing of sensory information. Attentional selection has been linked to altered cortical sensory responses and feature preferences (i.e., tuning). However, attentional modulation of feature selectivity during search is largely unexplored. Here we map the spatiotemporal profile of feature selectivity during singleton search. Monkeys performed search where a pop-out feature determined the target of attention. We recorded laminar neural responses from visual area V4. We first identified “feature columns” which showed preference for individual colors. In the unattended condition, feature columns were significantly more selective in superficial relative to middle and deep layers. Attending a stimulus increased selectivity in all layers but not equally. Feature selectivity increased most in the deep layers, leading to higher selectivity in extragranular layers as compared to the middle layer. This attention-induced enhancement was rhythmically gated in phase with the beta-band local field potential. Beta power dominated both extragranular laminar compartments, but current source density analysis pointed to an origin in superficial layers, specifically. While beta-band power was present regardless of attentional state, feature selectivity was only gated by beta in the attended condition. Neither the beta oscillation nor its gating of feature selectivity varied with microsaccade production. Importantly, beta modulation of neural activity predicted response times, suggesting a direct link between attentional gating and behavioral output. Together, these findings suggest beta-range synaptic activation in V4's superficial layers rhythmically gates attentional enhancement of feature tuning in a way that affects the speed of attentional selection.

视觉搜索（visual search）是探究注意力与感官信息加工如何交互作用的经典实验范式。注意选择与皮层感官反应及特征偏好（feature preferences，即调谐特性）的改变相关联。然而，搜索过程中特征选择性的注意调控仍未得到充分探索。本研究绘制了单例搜索（singleton search）过程中特征选择性的时空分布特征。实验中，猴子完成基于凸显特征（pop-out feature）确定注意靶标的视觉搜索任务，我们从视觉皮层V4区记录了分层神经活动。我们首先识别出对单一颜色具有偏好的“特征列（feature columns）”。在非注意条件下，特征列在表层皮层的选择性显著高于中层与深层皮层。对刺激的注意会提升所有皮层层的选择性，但提升程度不均一。深层皮层的特征选择性提升幅度最大，最终导致颗粒外皮层（extragranular layers）的选择性高于中层皮层。这种注意诱导的选择性提升会与β频段局部场电位（beta-band local field potential）同相位地受到节律性门控。β频段功率在所有颗粒外皮层分层区域均占主导，但电流源密度（current source density）分析明确显示其起源于表层皮层。尽管β频段功率的存在不受注意状态影响，但特征选择性仅在注意条件下受到β频段的门控调控。β节律及其对特征选择性的门控均未随微扫视（microsaccade）的产生而发生变化。重要的是，神经活动的β频段调制能够预测反应时，这表明注意门控与行为输出之间存在直接关联。综上，本研究结果表明，V4区表层皮层的β频段突触激活会节律性门控特征调谐的注意增强效应，进而影响注意选择的速度。