Two-phase model of the basal ganglia: implications for discontinuous control of the motor system.
Two-phase model of the basal ganglia: implications for discontinuous control of the motor system.
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基底神经节的两相模型：对运动系统不连续控制的影响。
DOI：
10.1098/rstb.2013.0489
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Lisman,John
中科院分区：
文献类型：
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作者：
Lisman,John
在这篇文章中，我指出，简单的单相模型的作用，基底神经节在行动选择有一个问题。此外，我建议一个解决方案的行动选择和运动系统的组织具有重大意义。在目前的模型中，纹状体通过基于先前条件反射添加偏差来评估多个潜在动作。这些偏差可能出现在直接（偏向）和间接（偏向）途径中。这些偏见共同影响最终选择哪种行动。为了有效的条件反射发生，一个积极的结果必须选择性地加强纹状体对所选动作的偏好（通过多巴胺能机制）。然而，这是有问题的，因为在选择过程中，所有潜在的行动选择都会影响纹状体细胞的放电模式;因此，目前还不清楚代表所选计划的突触如何被选择性地加强。我建议一个简单的解决方案，其中纹状体有两个功能阶段。在第一阶段，基底神经节为多个潜在的动作（使用直接和间接途径）提供偏置，导致在皮层中选择单个动作。在第二阶段，所选动作的传出副本被发送到纹状体，在那里它有助于建立该动作的资格迹线。当随后的多巴胺能强化作用于这一痕迹时，只会导致所选动作的偏向性得到特定的加强。与这个模型相一致的是，记录显示了选择后施加到纹状体上的与所选择的动作相对应的信号。基底神经节功能双相的存在意味着动作选择的决定以不连续的方式发送到运动系统。如果电动机系统也不连续地操作，这将不会有问题。我将回顾表明这是事实的证据，特别是行动是由大约10 Hz的振荡组织的。
In this article, I point out that simple one-phase models of the role of the basal ganglia in action selection have a problem. Furthermore, I suggest a solution with major implications for the organization of the action-selection and motor systems. In current models, the striatum evaluates multiple potential actions by adding biases based on previous conditioning. These biases may arise in both the direct (bias for) and indirect (bias against) pathways. Together, these biases influence which action is ultimately chosen. For efficient conditioning to occur, a positive outcome must selectively strengthen the striatal bias for the chosen action (via a dopaminergic mechanism). This is problematic, however, because all potential action choices have influenced firing patterns in striatal cells during the selection process; it is therefore unclear how the synapses that represent the chosen plan could be selectively strengthened. I suggest a simple solution in which the striatum has two functional phases. In the first phase, the basal ganglia provide biases for multiple potential actions (using both the direct and indirect pathways), leading to the choice of a single action in the cortex. In the second phase, an efference copy of the chosen action is sent to the striatum, where it contributes to the establishment of the eligibility trace for that action. This trace, when acted on by subsequent dopaminergic reinforcement, leads to specific strengthening of the bias only for the chosen action. Consistent with this model, recordings show post-choice imposition onto the striatum of signals corresponding to the chosen action. The existence of dual phases of basal ganglia function implies that decisions about action choice are sent to the motor system in a discontinuous manner. This would not be problematic if the motor system also operated discontinuously. I will review evidence suggesting that this is the case, notably that action is organized by approximately 10 Hz oscillations.