Stimulus selectivity and spatial coherence of gamma components of the local field potential.
Stimulus selectivity and spatial coherence of gamma components of the local field potential.
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DOI：
10.1523/jneurosci.0645-11.2011
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发表时间：
2011-06-22
期刊：
影响因子：
--
通讯作者：
Kohn A
中科院分区：
文献类型：
--
作者：
Jia X;Smith MA;Kohn A
局部场电位（LFP）的伽马频率为许多感知和认知现象提供了生理关联，并被认为在皮层功能中发挥作用。了解伽马的空间范围及其与峰值活动的关系对于解释该信号和阐明其功能至关重要，但之前的研究对这些特性提供了广泛不同的观点。我们利用植入猕猴初级视觉皮层的微电极阵列同时记录lfp和尖峰活动来解决这些问题。我们发现伽马的空间范围及其与局部尖峰活动的关系依赖于刺激。小光栅，以及那些被噪声掩盖的光栅，诱导频谱功率的宽带增长。这个信号的调谐与尖峰活动相似，并且具有有限的空间相干性。另一方面，大型光栅会产生一种伽马节奏，其特征是独特的光谱“碰撞”，这在广泛分离的位置上是一致的。这个信号被很好地调谐，但它对刺激的偏好在不同的皮层上是相似的。这种全局伽马节律的偏好对适应很敏感，在某种程度上，它放大了视觉刺激的神经元表征中的偏见。因此，伽马射线有两个来源，反映了神经集合活动的不同空间尺度。我们的研究结果表明，不存在一个单一的、固定的系综对伽马有贡献，伽马的选择性不能用来推断其空间范围。
The gamma frequencies of the local field potential (LFP) provide a physiological correlate for numerous perceptual and cognitive phenomena and have been proposed to play a role in cortical function. Understanding the spatial extent of gamma and its relationship to spiking activity is critical for interpreting this signal and elucidating its function, but previous studies have provided widely disparate views of these properties. We addressed these issues by simultaneously recording LFPs and spiking activity using microelectrode arrays implanted in the primary visual cortex of macaque monkeys. We find that the spatial extent of gamma and its relationship to local spiking activity is stimulus dependent. Small gratings, and those masked with noise, induce a broadband increase in spectral power. This signal is tuned similarly to spiking activity and has limited spatial coherence. Large gratings, on the other hand, induce a gamma rhythm characterized by a distinctive spectral “bump”, which is coherent across widely separated sites. This signal is well tuned, but its stimulus preference is similar across millimeters of cortex. The preference of this global gamma rhythm is sensitive to adaptation, in a manner consistent with it magnifying a bias in the neuronal representation of visual stimuli. Gamma thus arises from two sources that reflect different spatial scales of neural ensemble activity. Our results show that there is not a single, fixed ensemble contributing to gamma and that the selectivity of gamma cannot be used to infer its spatial extent.