BOLD temporal dynamics of rat superior colliculus and lateral geniculate nucleus following short duration visual stimulation.
BOLD temporal dynamics of rat superior colliculus and lateral geniculate nucleus following short duration visual stimulation.
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DOI：
10.1371/journal.pone.0018914
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发表时间：
2011-04-29
期刊：
影响因子：
3.7
通讯作者：
Wu EX
中科院分区：
文献类型：
--
作者：
Lau C;Zhou IY;Cheung MM;Chan KC;Wu EX
上级丘（SC）和外侧膝状体核（LGN）是重要的视觉皮质下结构。我们对视觉的大部分理解是使用侵入性和小视场（FOV）技术获得的。在这项研究中，我们使用非侵入性，大视野血氧水平依赖（BOLD）功能磁共振成像测量短时间（1秒）视觉刺激后的SC和LGN的反应时间动态。实验在7特斯拉下对Sprague道利大鼠的一只眼睛进行闪光刺激。相干回波和自旋回波序列用于提供互补信息。在注射单晶氧化铁纳米颗粒（MION）（一种血管造影剂）后，从一只大鼠中采集解剖图像。BOLD反应集中在对侧SC和LGN。在LGN信号之前0.2±0.2 s，用梯度回波测量的SC BOLD信号上升到最大幅度（PEAK）的50%（p<0.05）。LGN信号在SC信号之前1.4±1.2 s恢复到峰值的50%（p<0.05）。这些结果表明SC信号比LGN信号上升得更快，但稳定得更慢。自旋回波结果支持这些发现。MION后图像显示SC和LGN位于大血管下方。这种皮质下脉管系统类似于皮质中的脉管系统，皮质中的脉管系统也位于大血管下方。的LGN在于更接近大血管比大部分的SC。SC和LGN之间的响应时间的差异是非常相似的深和浅的皮质层之间的电刺激，这是相关的深度依赖性血管扩张率。这与皮质下和皮质之间血管系统的相似性相结合，表明SC和LGN的时间差异也与深度依赖性扩张率有关。这项研究首次表明，BOLD反应在大鼠SC和LGN后短时间的视觉刺激是暂时不同的。
The superior colliculus (SC) and lateral geniculate nucleus (LGN) are important subcortical structures for vision. Much of our understanding of vision was obtained using invasive and small field of view (FOV) techniques. In this study, we use non-invasive, large FOV blood oxygenation level-dependent (BOLD) fMRI to measure the SC and LGN's response temporal dynamics following short duration (1 s) visual stimulation. Experiments are performed at 7 tesla on Sprague Dawley rats stimulated in one eye with flashing light. Gradient-echo and spin-echo sequences are used to provide complementary information. An anatomical image is acquired from one rat after injection of monocrystalline iron oxide nanoparticles (MION), a blood vessel contrast agent. BOLD responses are concentrated in the contralateral SC and LGN. The SC BOLD signal measured with gradient-echo rises to 50% of maximum amplitude (PEAK) 0.2±0.2 s before the LGN signal (p<0.05). The LGN signal returns to 50% of PEAK 1.4±1.2 s before the SC signal (p<0.05). These results indicate the SC signal rises faster than the LGN signal but settles slower. Spin-echo results support these findings. The post-MION image shows the SC and LGN lie beneath large blood vessels. This subcortical vasculature is similar to that in the cortex, which also lies beneath large vessels. The LGN lies closer to the large vessels than much of the SC. The differences in response timing between SC and LGN are very similar to those between deep and shallow cortical layers following electrical stimulation, which are related to depth-dependent blood vessel dilation rates. This combined with the similarities in vasculature between subcortex and cortex suggest the SC and LGN timing differences are also related to depth-dependent dilation rates. This study shows for the first time that BOLD responses in the rat SC and LGN following short duration visual stimulation are temporally different.
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