Synchronous chaos and broad band gamma rhythm in a minimal multi-layer model of primary visual cortex.
Synchronous chaos and broad band gamma rhythm in a minimal multi-layer model of primary visual cortex.
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DOI：
10.1371/journal.pcbi.1002176
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发表时间：
2011-10
影响因子：
4.3
通讯作者：
Hansel D
中科院分区：
文献类型：
--
作者：
Battaglia D;Hansel D
视觉诱导的神经元活动在V1显示一个显着的γ-波段组件，这是调制的刺激属性。有人认为，同步振荡有助于这些伽马波段的活动。然而，不同实验的局部场电位（LFPs）分析揭示了这种诱导活性的振荡行为程度的相当大的差异。对比度相关的功率增强确实可以在伽马频率范围中的宽频带上发生，并且频谱峰值可能根本不会出现。此外，即使观察到振荡，它们也会在非常少的周期内经历时间去相关。这在以前的伽马振荡网络建模中并不容易解释。我们在这里认为，皮质层之间的相互作用可以负责这种快速去相关。我们研究了一个V1超柱模型，嵌入了对皮层多层结构的简化描述。当刺激对比度较低时，诱导的活动只有弱同步性，并且网络瞬时共振而不产生集体振荡。另一方面，当对比度高时，诱导的活动经历同步振荡，具有表示同步混沌状态的不规则时空结构。因此，人口活动经历快速的时间去相关，伴随着快速阻尼的振荡LFPs自相关图和LFPs功率谱的峰值展宽。我们表明，层间耦合的强度至关重要地影响这种时空结构。我们预测，第VI层失活应引起的LFP的光谱特性的全球变化，反映了他们的较慢的时间去相关层间反馈的情况下。最后，我们认为，在我们的模型中出现同步混沌的机制实际上是非常普遍的。它源于这样一个事实，即由局部延迟抑制引起的伽马振荡在与足够强的激发耦合时倾向于发展混沌。视觉刺激诱发视皮层神经元反应。当所用刺激的对比度增加时，这种诱导活动的功率在宽频率范围（30-100 Hz）内得到提升，称为“伽马波段”。人们很容易假设，这种现象是由于振荡的出现，在这种振荡中，许多神经元以有节奏的方式集体放电。然而，以前的模型试图解释使用同步振荡的对比度相关的功率增强未能再现所观察到的光谱，因为它们起源于不切实际的尖锐的光谱峰。我们研究的目的是调和宽带功率谱的同步振荡。我们认为，在这里，由于在皮层组织的不同深度的神经元群体之间的相互作用，诱导的振荡反应是同步的，但在同一时间，混乱。动力学的混沌性质使得有可能具有宽带功率谱和同步性。我们的建模研究使我们能够制定定性的实验预测，为我们的理论提供了一个潜在的测试。我们预测，如果皮层层之间的相互作用被抑制，例如通过灭活深层神经元，诱导的反应可能会变得更有规律，窄孤立的峰可能会在其功率谱。
Visually induced neuronal activity in V1 displays a marked gamma-band component which is modulated by stimulus properties. It has been argued that synchronized oscillations contribute to these gamma-band activity. However, analysis of Local Field Potentials (LFPs) across different experiments reveals considerable diversity in the degree of oscillatory behavior of this induced activity. Contrast-dependent power enhancements can indeed occur over a broad band in the gamma frequency range and spectral peaks may not arise at all. Furthermore, even when oscillations are observed, they undergo temporal decorrelation over very few cycles. This is not easily accounted for in previous network modeling of gamma oscillations. We argue here that interactions between cortical layers can be responsible for this fast decorrelation. We study a model of a V1 hypercolumn, embedding a simplified description of the multi-layered structure of the cortex. When the stimulus contrast is low, the induced activity is only weakly synchronous and the network resonates transiently without developing collective oscillations. When the contrast is high, on the other hand, the induced activity undergoes synchronous oscillations with an irregular spatiotemporal structure expressing a synchronous chaotic state. As a consequence the population activity undergoes fast temporal decorrelation, with concomitant rapid damping of the oscillations in LFPs autocorrelograms and peak broadening in LFPs power spectra. We show that the strength of the inter-layer coupling crucially affects this spatiotemporal structure. We predict that layer VI inactivation should induce global changes in the spectral properties of induced LFPs, reflecting their slower temporal decorrelation in the absence of inter-layer feedback. Finally, we argue that the mechanism underlying the emergence of synchronous chaos in our model is in fact very general. It stems from the fact that gamma oscillations induced by local delayed inhibition tend to develop chaos when coupled by sufficiently strong excitation. Visual stimulation elicits neuronal responses in visual cortex. When the contrast of the used stimuli increases, the power of this induced activity is boosted over a broad frequency range (30–100 Hz), called the “gamma band.” It would be tempting to hypothesize that this phenomenon is due to the emergence of oscillations in which many neurons fire collectively in a rhythmic way. However, previous models trying to explain contrast-related power enhancements using synchronous oscillations failed to reproduce the observed spectra because they originated unrealistically sharp spectral peaks. The aim of our study is to reconcile synchronous oscillations with broad-band power spectra. We argue here that, thanks to the interaction between neuronal populations at different depths in the cortical tissue, the induced oscillatory responses are synchronous, but, at the same time, chaotic. The chaotic nature of the dynamics makes it possible to have broad-band power spectra together with synchrony. Our modeling study allows us formulating qualitative experimental predictions that provide a potential test for our theory. We predict that if the interactions between cortical layers are suppressed, for instance by inactivating neurons in deep layers, the induced responses might become more regular and narrow isolated peaks might develop in their power spectra.
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影响因子：
64.8
作者：
BOLZ, J;GILBERT, CD
通讯作者：
GILBERT, CD
影响因子：
56.9
作者：
Anderson, JS;Lampl, I;Ferster, D
通讯作者：
Ferster, D
影响因子：
1.9
作者：
Badel, Laurent;Lefort, Sandrine;Richardson, Magnus J. E.
通讯作者：
Richardson, Magnus J. E.
DOI：
10.1523/jneurosci.4222-09.2010
发表时间：
2010-02-24
期刊：
The Journal of neuroscience : the official journal of the Society for Neuroscience
影响因子：
--
作者：
Ardid S;Wang XJ;Gomez-Cabrero D;Compte A
通讯作者：
Compte A
影响因子：
2.9
作者：
Brunel, Nicolas;Hansel, David
通讯作者：
Hansel, David