Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
College of Medicine and Health, University of Exeter, EX1 2LU, UK.
Cereb Cortex. 2021 Jun 10;31(7):3266-3284. doi: 10.1093/cercor/bhab007.
Top-down attention, controlled by frontal cortical areas, is a key component of cognitive operations. How different neurotransmitters and neuromodulators flexibly change the cellular and network interactions with attention demands remains poorly understood. While acetylcholine and dopamine are critically involved, glutamatergic receptors have been proposed to play important roles. To understand their contribution to attentional signals, we investigated how ionotropic glutamatergic receptors in the frontal eye field (FEF) of male macaques contribute to neuronal excitability and attentional control signals in different cell types. Broad-spiking and narrow-spiking cells both required N-methyl-D-aspartic acid and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor activation for normal excitability, thereby affecting ongoing or stimulus-driven activity. However, attentional control signals were not dependent on either glutamatergic receptor type in broad- or narrow-spiking cells. A further subdivision of cell types into different functional types using cluster-analysis based on spike waveforms and spiking characteristics did not change the conclusions. This can be explained by a model where local blockade of specific ionotropic receptors is compensated by cell embedding in large-scale networks. It sets the glutamatergic system apart from the cholinergic system in FEF and demonstrates that a reduction in excitability is not sufficient to induce a reduction in attentional control signals.
自上而下的注意力由额皮质区域控制，是认知操作的关键组成部分。不同的神经递质和神经调质如何灵活地改变细胞和网络与注意力需求的相互作用，仍知之甚少。虽然乙酰胆碱和多巴胺起着至关重要的作用，但谷氨酸能受体被认为起着重要作用。为了了解它们对注意力信号的贡献，我们研究了雄性猕猴额眼区（FEF）中的离子型谷氨酸能受体如何为不同细胞类型的神经元兴奋性和注意力控制信号做出贡献。宽脉冲和窄脉冲细胞都需要 N-甲基-D-天冬氨酸和 α-氨基-3-羟基-5-甲基-4-异恶唑丙酸受体的激活以维持正常的兴奋性，从而影响持续或刺激驱动的活动。然而，在宽脉冲和窄脉冲细胞中，注意力控制信号并不依赖于任何一种谷氨酸能受体类型。使用基于尖峰波形和尖峰特征的聚类分析对细胞类型进行进一步细分，并没有改变结论。这可以用一个模型来解释，即局部阻断特定的离子型受体可以通过细胞嵌入在大规模网络中得到补偿。这使得谷氨酸能系统在 FEF 中与胆碱能系统区别开来，并表明兴奋性的降低不足以诱导注意力控制信号的降低。
