Competition between feedback loops underlies normal and pathological dynamics in the basal ganglia
Competition between feedback loops underlies normal and pathological dynamics in the basal ganglia
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DOI：
10.1523/jneurosci.5050-05.2006
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发表时间：
2006-03-29
影响因子：
5.3
通讯作者：
Hansel, D
中科院分区：
文献类型：
--
作者：
Leblois, A;Boraud, T;Hansel, D
在正常动物中进行的实验表明，基底神经节（BG）在运动程序选择中至关重要。BG也参与运动障碍。特别是，BG神经元的活动在帕金森病动物和患者比正常individuals.We提出了一个新的模型BG的运动部分的功能和功能障碍的振荡和更同步。我们假设纹状体、丘脑底核、内苍白球（GPi）、丘脑和皮质参与了闭合的反馈回路。直接环路（皮质-纹状体-GPi-丘脑-皮质）和超直接环路（皮质-丘脑底核-GPi-丘脑-皮质）在该模型中起关键作用，它们具有不同的极性。我们发现，这两个循环之间的竞争提供了BG-皮层系统的能力，执行运动程序的选择。假设多巴胺增强皮质纹状体突触传递，我们证明，在我们的模型中，中度多巴胺耗竭导致行动选择能力的完全丧失。高损耗可导致同步振荡。这些修改的网络动力学状态干之间的不平衡的反馈，在直接和超直接的循环时，多巴胺是depleted.Our模型预测，选择能力的损失发生在振荡的外观，这表明帕金森氏症的运动障碍是没有直接关系到异常的振荡活动。我们的模型的另一个主要预测是，由超直接回路驱动的同步振荡出现在BG纹状体失活后。
Experiments performed in normal animals suggest that the basal ganglia (BG) are crucial in motor program selection. BG are also involved in movement disorders. In particular, BG neuronal activity in parkinsonian animals and patients is more oscillatory and more synchronous than in normal individuals.We propose a new model for the function and dysfunction of the motor part of BG. We hypothesize that the striatum, the subthalamic nucleus, the internal pallidum (GPi), the thalamus, and the cortex are involved in closed feedback loops. The direct (cortex-striatum-GPi-thalamus-cortex) and the hyperdirect loops (cortex-subthalamic nucleus-GPi-thalamus-cortex), which have different polarities, play a key role in the model. We show that the competition between these two loops provides the BG-cortex system with the ability to perform motor program selection. Under the assumption that dopamine potentiates corticostriatal synaptic transmission, we demonstrate that, in our model, moderate dopamine depletion leads to a complete loss of action selection ability. High depletion can lead to synchronous oscillations. These modifications of the network dynamical state stem from an imbalance between the feedback in the direct and hyperdirect loops when dopamine is depleted.Our model predicts that the loss of selection ability occurs before the appearance of oscillations, suggesting that Parkinson's disease motor impairments are not directly related to abnormal oscillatory activity. Another major prediction of our model is that synchronous oscillations driven by the hyperdirect loop appear in BG after inactivation of the striatum.