Data from: Laminar microcircuitry of visual cortex producing attention-associated electric fields

Cognitive operations are widely studied by measuring electric fields through EEG and ECoG. However, despite their widespread use, the neural circuitry giving rise to these signals remains unknown because the functional architecture of cortical columns producing attention-associated electric fields has not been explored. Here, we detail the laminar cortical circuitry underlying an attention-associated electric field measured over posterior regions of the brain in humans and monkeys. First, we identified visual cortical area V4 as one plausible contributor to this attention-associated electric field through inverse modeling of cranial EEG in macaque monkeys performing a visual attention task. Next, we performed laminar neurophysiological recordings on the prelunate gyrus and identified the electric-field-producing dipoles as synaptic activity in distinct cortical layers of area V4. Specifically, activation in the extragranular layers of cortex resulted in the generation of the attention-associated dipole. Feature selectivity of a given cortical column determined the overall contribution to this electric field. Columns selective for the attended feature contributed more to the electric field than columns selective for a different feature. Last, the laminar profile of synaptic activity generated by V4 was sufficient to produce an attention-associated signal measurable outside of the column. These findings suggest that the top-down recipient cortical layers produce an attention-associated electric field that can be measured extracortically with the relative contribution of each column depending upon the underlying functional architecture.认知操作的相关研究广泛采用脑电图（Electroencephalogram, EEG）与皮层脑电（Electrocorticography, ECoG）技术来测量电场。然而，尽管这两类技术应用极为广泛，但产生此类信号的神经环路仍未明确，其原因在于尚未探究产生注意力相关电场的皮层柱（cortical columns）功能架构。本研究详细阐明了在人类与猕猴大脑后部区域测得的注意力相关电场背后的皮层分层环路机制。首先，我们通过对执行视觉注意力任务的猕猴的颅骨脑电图进行逆建模，确定视觉皮层V4区是该注意力相关电场的潜在来源之一。随后，我们在月状回（prelunate gyrus）开展了分层神经生理记录，确定产生电场的偶极子为V4区不同皮层层的突触活动。具体而言，皮层外颗粒层的激活会产生注意力相关偶极子。单个皮层柱的特征选择性决定了其对该电场的整体贡献程度：对被关注特征具有选择性的皮层柱，其对该电场的贡献要大于对其他特征具有选择性的皮层柱。最后，V4区产生的突触活动分层分布特征足以生成可在皮层柱外测得的注意力相关信号。上述研究结果表明，接收自上而下信号的皮层层会产生注意力相关电场，该电场可在皮层外被检测到，且每个皮层柱的相对贡献取决于其内在的功能架构。