Limited impact of homeostatic plasticity on motor learning in humans
Limited impact of homeostatic plasticity on motor learning in humans
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DOI：
10.1016/j.neuropsychologia.2008.02.023
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发表时间：
2008-01-01
期刊：
影响因子：
2.6
通讯作者：
Nitsche, Michael A.
中科院分区：
文献类型：
--
作者：
Kuo, Min-Fang;Unger, Mandy;Nitsche, Michael A.
神经可塑性是响应环境需求而对网络连接进行适应性修改，并已被确定为学习的主要生理相关性。由于网络连接的不受限制的神经可塑性修改将导致系统的稳定，因此已提出化生修改规则以将可塑性连接变化保持在有用的动态范围内。在这方面，实现突触强化的修改阈值被认为与各个神经元的活动历史负相关，即先前的高活动增强了突触强化的阈值，反之亦然。然而，形塑性与实际学习过程的相关性迄今为止尚未得到测试。我们在执行串行反应时间任务（SRTT）、顺序运动学习范例和通过经颅直流电刺激（tDCS）的反应时间任务（RTT）之前降低或增强了运动皮层的兴奋性。如果稳态规则适用，兴奋性降低的阴极 tDCS 应改善随后的运动学习，特别是与部分 NMDA 受体激动剂 D-环丝氨酸联合使用时，它选择性地增强活性受体的功效，而兴奋性增强的阳极 tDCS 应降低其效果。只有当与 D-环丝氨酸结合时，阳极 tDCS 的结果才符合稳态可塑性规则。我们得出的结论是，正如此处所测试的，稳态可塑性对内隐顺序运动学习的影响有限。 (C) 2008 Elsevier Ltd. 保留所有权利。
Neuroplasticity is the adaptive modification of network connectivity in response to environmental demands and has been identified as a major physiological correlate of learning. Since unrestricted neuroplastic modifications of network connectivity will result in a cle-stabilization of the system, metaplastic modification rules have been proposed for keeping plastic connectivity changes within a useful dynamic range. In this connection, the modification threshold to achieve synaptic strengthening is thought to correlate negatively with the history of activity of the respective neurons, i.e. high previous activity enhances the threshold for synaptic strengthening and vice versa. However, the relevance of metaplasticity for actual learning processes has not been tested so far. We reduced or enhanced motor cortex excitability before performance of the serial reaction time task (SRTT), a sequential motor learning paradigm, and a reaction time task (RTT) by transcranial direct current stimulation (tDCS). If homeostatic rules apply, excitability-diminishing cathodal tDCS should improve subsequent motor learning, especially if combined with the partial NMDA receptor-agoniSt D-cycloserine, which selectively enhances efficacy of active receptors, while excitability-enhancing anodal tDCS should reduce it. Only the results for anodal tDCS, when combined with D-cycloserine, were in accordance with the rules of homeostatic plasticity. We conclude that homeostatic plasticity, as tested here, has a limited influence on implicit sequential motor learning. (C) 2008 Elsevier Ltd. All rights reserved.