Space coding by gamma oscillations in the barn owl optic tectum.
Space coding by gamma oscillations in the barn owl optic tectum.
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DOI：
10.1152/jn.00965.2010
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发表时间：
2011-05
影响因子：
2.5
通讯作者：
D. Sridharan;K. Boahen;E. Knudsen
中科院分区：
文献类型：
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作者：
D. Sridharan;K. Boahen;E. Knudsen
局部场电位 (LFP) 的伽马带 (25-140 Hz) 振荡是由哺乳动物前脑中的感觉刺激引起的，并且当动物注意这些刺激时，其幅度可能会受到强烈调节。视顶盖 (OT) 是一种中脑结构，已知有助于多模式感觉处理、凝视控制和注意力。我们发现，空间局部刺激的呈现，无论是视觉还是听觉，都会引起强烈的伽马振荡，在猫头鹰 OT 的浅层（视觉）和深层（多模态）层中具有独特的特性。在各层之间，伽马功率针对刺激位置进行了大幅调整，并以地形方式表示空间。在表层中，感应 LFP 功率在低伽马频带 (25-90 Hz) 中达到强烈峰值，并随着宽范围对比度的视觉对比度逐渐增加。这些层中记录的尖峰包括假定的轴突（输入）尖峰，其编码的刺激特性与伽马振荡几乎相同，并且与振荡紧密锁相，这表明它们有助于 LFP 振荡。在深层，感应 LFP 功率分布在低和高 (90-140 Hz) 伽玛波段，并且往往在相对较低的视觉对比度下达到最大值。在这些层中，平均而言，与体细胞尖峰速率以及与伽马振荡同步的体细胞尖峰相比，伽马功率针对刺激位置的调整更为敏锐。深层神经元的这种伽马同步放电可以提供高分辨率的时间代码，用于指示显着感觉刺激的位置。
Gamma-band (25-140 Hz) oscillations of the local field potential (LFP) are evoked by sensory stimuli in the mammalian forebrain and may be strongly modulated in amplitude when animals attend to these stimuli. The optic tectum (OT) is a midbrain structure known to contribute to multimodal sensory processing, gaze control, and attention. We found that presentation of spatially localized stimuli, either visual or auditory, evoked robust gamma oscillations with distinctive properties in the superficial (visual) layers and in the deep (multimodal) layers of the owl's OT. Across layers, gamma power was tuned sharply for stimulus location and represented space topographically. In the superficial layers, induced LFP power peaked strongly in the low-gamma band (25-90 Hz) and increased gradually with visual contrast across a wide range of contrasts. Spikes recorded in these layers included presumptive axonal (input) spikes that encoded stimulus properties nearly identically with gamma oscillations and were tightly phase locked with the oscillations, suggesting that they contribute to the LFP oscillations. In the deep layers, induced LFP power was distributed across the low and high (90-140 Hz) gamma-bands and tended to reach its maximum value at relatively low visual contrasts. In these layers, gamma power was more sharply tuned for stimulus location, on average, than were somatic spike rates, and somatic spikes synchronized with gamma oscillations. Such gamma synchronized discharges of deep-layer neurons could provide a high-resolution temporal code for signaling the location of salient sensory stimuli.