Vaadia E, Aertsen A, Nelken I
Department of Physiology, Hadassah School of Medicine, Hebrew University, Jerusalem, Israel.
Proc Biol Sci. 1995 Sep 22;261(1362):407-10. doi: 10.1098/rspb.1995.0167.
In a recent paper, Vaadia et al. demonstrated that patterns of firing correlation between single neurons in the cortex of behaving monkeys can be modified within a fraction of a second. These changes occur in relation to sensory stimuli and behavioral events, and even without modulations of the neurons' firing rates. These findings call for a revision of prevailing models of neural coding that solely rely on single neuron firing rates. In a defense of these models, Friston put forward an alternative explanation, proposing that the observed correlation dynamics emerge solely from co-modulations of the firing rates of each of the neurons, while the strength of their interaction remains constant. To test this possibility we re-examined the data, adopting Friston's 'neuronal transients' model, and the associated equations and procedures. We found that, to explain the dynamic correlation between a pair of neurons, the alternative interpretation requires that each neuron's response to a single stimulus is composed of a relatively large number of independent components, which co-vary with their counterparts in the companion neuron. This large number of components and their shapes lead us to conclude that, although in principle possible, the neuronal transients model: (i) does not provide a simpler explanation of the experimental results; and (ii) cannot explain these results without itself deviating significantly from most rate code models.
在最近的一篇论文中，瓦迪亚等人证明，行为猴子皮层中单个神经元之间的放电相关性模式可在几分之一秒内改变。这些变化与感觉刺激和行为事件有关，甚至在神经元放电率未受调制的情况下也会发生。这些发现要求对仅依赖单个神经元放电率的主流神经编码模型进行修正。为维护这些模型，弗里斯顿提出了另一种解释，认为观察到的相关性动态仅源于每个神经元放电率的共同调制，而它们相互作用的强度保持不变。为检验这种可能性，我们采用弗里斯顿的“神经元瞬变”模型以及相关方程和程序重新审视了数据。我们发现，为解释一对神经元之间的动态相关性，这种替代性解释要求每个神经元对单个刺激的反应由相对大量的独立成分组成，这些成分与其配对神经元中的对应成分共同变化。如此大量的成分及其形状使我们得出结论，虽然原则上有可能，但神经元瞬变模型：（i）并未对实验结果提供更简单的解释；（ii）若不显著偏离大多数速率编码模型，就无法解释这些结果。
