An integrator circuit in cerebellar cortex.
An integrator circuit in cerebellar cortex.
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小脑皮层中的积分器电路。
DOI：
10.1111/ejn.12272
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Maex R
中科院分区：
文献类型：
--
作者：
Maex R
大脑建立身体和外部世界的动态模型，以预测行为和刺激的后果。一个著名的例子是眼球运动积分器，它通过对眼球运动速度命令进行数学积分来预测作用在眼球上的位置相关弹性力。基于反馈激励、侧抑制或神经元内在非线性，已经提出了许多神经整合模型。我们在这里报告说，小脑皮层的计算模型，一个结构，认为实现动态模型，揭示了一个迄今未被认识到的积分电路。在该模型中，包括浦肯野细胞，分子层中间神经元和平行纤维，浦肯野细胞能够产生持续超过10秒的反应，神经元和网络机制都作出了贡献。通过阈下电压波动激活体细胞快钠电流能够维持脉冲诱发的分级持续活动，而浦肯野细胞通过复发性轴突侧支的侧抑制进一步延长了对阶梯波和正弦波刺激的反应。浦肯野细胞的反应以一个时间常数衰减，其值取决于其基线尖峰速率，在低速率（< 1/s）和高速率（> 30/s）下积分消失。该模型预测，小脑皮层的明显快速电路可能控制缓慢过程的时间，而不必依赖于感觉反馈。因此，小脑皮质可能包含一个自适应的时间积分器，积分对基线尖峰频率的敏感性提供了反应时间常数可塑性的潜在机制。
The brain builds dynamic models of the body and the outside world to predict the consequences of actions and stimuli. A well‐known example is the oculomotor integrator, which anticipates the position‐dependent elasticity forces acting on the eye ball by mathematically integrating over time oculomotor velocity commands. Many models of neural integration have been proposed, based on feedback excitation, lateral inhibition or intrinsic neuronal nonlinearities. We report here that a computational model of the cerebellar cortex, a structure thought to implement dynamic models, reveals a hitherto unrecognized integrator circuit. In this model, comprising Purkinje cells, molecular layer interneurons and parallel fibres, Purkinje cells were able to generate responses lasting more than 10 s, to which both neuronal and network mechanisms contributed. Activation of the somatic fast sodium current by subthreshold voltage fluctuations was able to maintain pulse‐evoked graded persistent activity, whereas lateral inhibition among Purkinje cells via recurrent axon collaterals further prolonged the responses to step and sine wave stimulation. The responses of Purkinje cells decayed with a time‐constant whose value depended on their baseline spike rate, with integration vanishing at low (< 1 per s) and high rates (> 30 per s). The model predicts that the apparently fast circuit of the cerebellar cortex may control the timing of slow processes without having to rely on sensory feedback. Thus, the cerebellar cortex may contain an adaptive temporal integrator, with the sensitivity of integration to the baseline spike rate offering a potential mechanism of plasticity of the response time‐constant.