Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
J Neurosci. 2011 Jul 27;31(30):11028-38. doi: 10.1523/JNEUROSCI.0193-11.2011.
For optimal sensory processing, neural circuits must extract novel, unpredictable signals from the redundant sensory input in which they are embedded, but the detailed cellular and network mechanisms that implement such selective cancellation are presently unknown. Using a combination of modeling and experiment, we characterize in detail a cerebellar circuit in weakly electric fish, showing how it can carry out this computation. We use a model incorporating the wide range of experimentally estimated parallel fiber feedback delays and a burst-induced LTD rule derived from in vitro experiments to explain the precise cancellation of redundant signals observed in vivo. Our model demonstrates how the backpropagation-dependent burst dynamics adjusts the temporal pairing width of the plasticity mechanism to precisely match the frequency of the redundant signal. The model also makes the prediction that this cerebellar feedback pathway must be composed of frequency-tuned channels; this prediction is subsequently verified in vivo, highlighting a novel and general capability of cerebellar circuitry.
为实现最佳的感觉处理,神经回路必须从其嵌入的冗余感觉输入中提取新颖的、不可预测的信号,但目前尚不清楚实现这种选择性消除的详细细胞和网络机制。我们结合使用建模和实验,详细描述了弱电鱼的小脑回路,展示了它如何进行这种计算。我们使用一个模型,其中包含了广泛的实验估计的平行纤维反馈延迟,以及从体外实验中得出的突发诱导 LTD 规则,来解释在体内观察到的精确消除冗余信号的现象。我们的模型演示了依赖于反向传播的突发动力学如何调整可塑性机制的时间配对宽度,以精确匹配冗余信号的频率。该模型还预测了这种小脑反馈途径必须由频率调谐通道组成;这一预测随后在体内得到验证,突出了小脑回路的一种新颖而普遍的能力。