Pietersen Alexander N J, Cheong Soon Keen, Munn Brandon, Gong Pulin, Martin Paul R, Solomon Samuel G
Australian Research Council Centre of Excellence for Integrative Brain Function, University of Sydney, Australia.
Save Sight Institute, University of Sydney Eye Hospital Campus, Sydney, Australia.
J Physiol. 2017 Jul 1;595(13):4475-4492. doi: 10.1113/JP273569. Epub 2017 Mar 10.
How parallel are the primate visual pathways? In the present study, we demonstrate that parallel visual pathways in the dorsal lateral geniculate nucleus (LGN) show distinct patterns of interaction with rhythmic activity in the primary visual cortex (V1). In the V1 of anaesthetized marmosets, the EEG frequency spectrum undergoes transient changes that are characterized by fluctuations in delta-band EEG power. We show that, on multisecond timescales, spiking activity in an evolutionary primitive (koniocellular) LGN pathway is specifically linked to these slow EEG spectrum changes. By contrast, on subsecond (delta frequency) timescales, cortical oscillations can entrain spiking activity throughout the entire LGN. Our results are consistent with the hypothesis that, in waking animals, the koniocellular pathway selectively participates in brain circuits controlling vigilance and attention.
The major afferent cortical pathway in the visual system passes through the dorsal lateral geniculate nucleus (LGN), where nerve signals originating in the eye can first interact with brain circuits regulating visual processing, vigilance and attention. In the present study, we investigated how ongoing and visually driven activity in magnocellular (M), parvocellular (P) and koniocellular (K) layers of the LGN are related to cortical state. We recorded extracellular spiking activity in the LGN simultaneously with local field potentials (LFP) in primary visual cortex, in sufentanil-anaesthetized marmoset monkeys. We found that asynchronous cortical states (marked by low power in delta-band LFPs) are linked to high spike rates in K cells (but not P cells or M cells), on multisecond timescales. Cortical asynchrony precedes the increases in K cell spike rates by 1-3 s, implying causality. At subsecond timescales, the spiking activity in many cells of all (M, P and K) classes is phase-locked to delta waves in the cortical LFP, and more cells are phase-locked during synchronous cortical states than during asynchronous cortical states. The switch from low-to-high spike rates in K cells does not degrade their visual signalling capacity. By contrast, during asynchronous cortical states, the fidelity of visual signals transmitted by K cells is improved, probably because K cell responses become less rectified. Overall, the data show that slow fluctuations in cortical state are selectively linked to K pathway spiking activity, whereas delta-frequency cortical oscillations entrain spiking activity throughout the entire LGN, in anaesthetized marmosets.
灵长类动物的视觉通路有多平行？在本研究中，我们证明背外侧膝状核（LGN）中的平行视觉通路与初级视觉皮层（V1）中的节律性活动呈现出不同的相互作用模式。在麻醉的狨猴的V1中，脑电图频谱会经历短暂变化，其特征是δ波段脑电图功率的波动。我们表明，在多秒时间尺度上，进化上原始的（konio细胞）LGN通路中的尖峰活动与这些缓慢的脑电图频谱变化有特定联系。相比之下，在亚秒（δ频率）时间尺度上，皮层振荡可以带动整个LGN中的尖峰活动。我们的结果与以下假设一致：在清醒动物中，konio细胞通路选择性地参与控制警觉和注意力的脑回路。
视觉系统中的主要传入皮层通路穿过背外侧膝状核（LGN），来自眼睛的神经信号首先在那里与调节视觉处理、警觉和注意力的脑回路相互作用。在本研究中，我们研究了LGN的大细胞（M）、小细胞（P）和konio细胞（K）层中正在进行的和视觉驱动的活动如何与皮层状态相关。我们在舒芬太尼麻醉的狨猴中，同时记录了LGN中的细胞外尖峰活动和初级视觉皮层中的局部场电位（LFP）。我们发现，在多秒时间尺度上，异步皮层状态（以δ波段LFP中的低功率为标志）与K细胞（而非P细胞或M细胞）中的高尖峰率相关。皮层异步在K细胞尖峰率增加之前1 - 3秒出现，这意味着存在因果关系。在亚秒时间尺度上，所有（M、P和K）类别的许多细胞中的尖峰活动与皮层LFP中的δ波锁相，并且在同步皮层状态下比在异步皮层状态下有更多细胞锁相。K细胞从低尖峰率到高尖峰率的转变不会降低其视觉信号传递能力。相比之下，在异步皮层状态下，K细胞传递的视觉信号的保真度提高，可能是因为K细胞的反应变得不那么整流。总体而言，数据表明，在麻醉的狨猴中，皮层状态的缓慢波动与K通路的尖峰活动有选择性联系，而δ频率的皮层振荡带动整个LGN中的尖峰活动。
