Neural field theory of synaptic metaplasticity with applications to theta burst stimulation
Neural field theory of synaptic metaplasticity with applications to theta burst stimulation
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DOI：
10.1016/j.jtbi.2013.09.021
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发表时间：
2014-01-07
影响因子：
2
通讯作者：
Robinson, P. A.
中科院分区：
文献类型：
--
作者：
Fung, P. K.;Robinson, P. A.
经颅磁刺激（TMS）具有很强的非线性可塑性效应。强调这种非线性的实验结果包括连续和间歇 theta 突发刺激（分别为 cTBS 和 iTBS），其中在连续情况下诱发抑郁，但每 2 秒刺激插入约 8 秒的关闭期，将诱发的可塑性改变为间歇情况下的增强。另一个非线性是 cTBS 和 iTBS 表现出剂量依赖性，其中刺激持续时间加倍会改变诱导可塑性的方向。本研究以前期实验结果为指导，假设了化塑性的特征，并制定了生理系统水平的可塑性理论来预测TMS实验。在这个理论中，可塑性信号传导诱导 NMDA 受体的可塑性，以进一步调节可塑性信号，随后是信号转导延迟可塑性表达。由于 NMDA 受体的这种可塑性会影响随后的可塑性诱导，因此它是化塑性的一种形式。将这种化塑性纳入最近的钙依赖性可塑性神经场理论中，为 Bienenstock、Cooper、Munro (1982) 的理论提供了生理学基础，其中突触后细胞内钙水平成为时间平均突触后活动的量度，并收敛到可塑性阈值以产生稳态效应。 TMS 协议反应的模拟表明，细胞内钙在阈值附近的振荡预测了上述 TMS 诱导的可塑性的非线性，以及实验发现的人际 TBS 反应极性，其中相同的协议可能对不同的受试者产生相反的可塑性效应。从而，为未来的实验和 TMS 协议优化提出建议。还探讨了通过空间扩展的平均场神经动力学的输入选择性。 (C) 2013 Elsevier Ltd. 保留所有权利。
Transcranial magnetic stimulation (TMS) is characterized by strong nonlinear plasticity effects. Experimental results that highlight such nonlinearity include continuous and intermittent theta-burst stimulations (cTBS and iTBS, respectively), where depression is induced in the continuous case, but insertion of an off period of around 8 s for every 2 s of stimulation changes the induced plasticity to potentiation in the intermittent case. Another nonlinearity is that cTBS and iTBS exhibit dosage dependency, where doubling of the stimulation duration changes the direction of induced plasticity. Guided by previous experimental results, this study postulates on the characteristics of metaplasticity and formulates a physiological system-level plasticity theory to predict TMS experiments. In this theory, plasticity signaling induces plasticity in NMDA receptors to modulate further plasticity signals, and is followed by a signal transduction delayed plasticity expression. Since this plasticity in NMDA receptor affects subsequent plasticity induction, it is a form of metaplasticity. Incorporating this metaplasticity into a recent neural field theory of calcium dependent plasticity gives a physiological basis for the theory of Bienenstock, Cooper, Munro (1982), where postsynaptic intracellular calcium level becomes the measure of temporal averaged postsynaptic activity, and converges to the plasticity threshold to give homeostatic effects. Simulations of TMS protocol responses show that intracellular calcium oscillations around the threshold predicts the aforementioned nonlinearities in TMS-induced plasticity, as well as the interpersonal TBS response polarity found experimentally, where the same protocol may induce opposite plasticity effect for different subjects. Thereby, recommendations for future experiments and TMS protocol optimizations are made. Input selectivity via spatially extended, mean field neural dynamics is also explored. (C) 2013 Elsevier Ltd. All rights reserved.