A Re-Examination of Hebbian-Covariance Rules and Spike Timing-Dependent Plasticity in Cat Visual Cortex in vivo.
A Re-Examination of Hebbian-Covariance Rules and Spike Timing-Dependent Plasticity in Cat Visual Cortex in vivo.
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DOI：
10.3389/fnsyn.2010.00147
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发表时间：
2010
影响因子：
3.7
通讯作者：
Shulz DE
中科院分区：
文献类型：
--
作者：
Frégnac Y;Pananceau M;René A;Huguet N;Marre O;Levy M;Shulz DE
Spike - time -dependent plasticity （STDP）被认为是皮层网络联想可塑性的普遍规律。然而，其在体内的功能作用的支持证据有限。特别是，很少有研究表明，在Hebbian或STDP治疗过程中，突触效率的改变和成人皮层感觉反应的改变同时发生。我们通过回顾和比较猫视觉皮层中两种类型的细胞调节的功能影响来解决这个问题。第一种方案被称为“协方差”方案，它遵循一个广义的Hebbian框架，对不同的刺激施加有监督的突触后和突触前活动率之间协方差的正、负变化。第二种方案基于细胞内记录，在体内复制了β -爆发模式（TBS）的变体，在体外成功诱导了长期增强。由于它被证明在电激活的丘脑输入和tbs诱导的突触后尖峰之间施加了精确的相关延迟，因此该协议可以被视为因果（“前-后-后”）STDP的探针。通过选择视域表征与细胞内记录的皮质感受野重叠的丘脑区域作为监督电刺激的传入部位，该方案可以寻找STDP与条件皮质感受野功能重组之间可能的相关性。以速率为基础的“协方差方案”在小猫和成人的V1皮层中都引起了感受野特性的显著和大幅度的变化。TBS stdp样方案在成人中产生了电激活丘脑通路突触增益的显著变化，但功能相关的统计学意义主要在群体水平上检测到。将我们的观察结果与文献进行比较，使我们重新审视成人皮层中脉冲时间依赖性增强的实验状态。我们提出在体内存在一个基于相关性的阈值，限制了stdp诱导的关键时期以外的变化的表达，这解释了在没有注意或奖励门控监督的情况下，感觉皮质加工过程中突触权重的稳定性。
Spike timing-dependent plasticity (STDP) is considered as an ubiquitous rule for associative plasticity in cortical networks in vitro. However, limited supporting evidence for its functional role has been provided in vivo. In particular, there are very few studies demonstrating the co-occurrence of synaptic efficiency changes and alteration of sensory responses in adult cortex during Hebbian or STDP protocols. We addressed this issue by reviewing and comparing the functional effects of two types of cellular conditioning in cat visual cortex. The first one, referred to as the “covariance” protocol, obeys a generalized Hebbian framework, by imposing, for different stimuli, supervised positive and negative changes in covariance between postsynaptic and presynaptic activity rates. The second protocol, based on intracellular recordings, replicated in vivo variants of the theta-burst paradigm (TBS), proven successful in inducing long-term potentiation in vitro. Since it was shown to impose a precise correlation delay between the electrically activated thalamic input and the TBS-induced postsynaptic spike, this protocol can be seen as a probe of causal (“pre-before-post”) STDP. By choosing a thalamic region where the visual field representation was in retinotopic overlap with the intracellularly recorded cortical receptive field as the afferent site for supervised electrical stimulation, this protocol allowed to look for possible correlates between STDP and functional reorganization of the conditioned cortical receptive field. The rate-based “covariance protocol” induced significant and large amplitude changes in receptive field properties, in both kitten and adult V1 cortex. The TBS STDP-like protocol produced in the adult significant changes in the synaptic gain of the electrically activated thalamic pathway, but the statistical significance of the functional correlates was detectable mostly at the population level. Comparison of our observations with the literature leads us to re-examine the experimental status of spike timing-dependent potentiation in adult cortex. We propose the existence of a correlation-based threshold in vivo, limiting the expression of STDP-induced changes outside the critical period, and which accounts for the stability of synaptic weights during sensory cortical processing in the absence of attention or reward-gated supervision.