Butz Markus, van Ooyen Arjen, Wörgötter Florentin
Bernstein Center for Computational Neuroscience Göttingen, University of Göttingen Göttingen, Germany.
Front Comput Neurosci. 2009 Aug 4;3:10. doi: 10.3389/neuro.10.010.2009. eCollection 2009.
It is still unclear to what extent structural plasticity in terms of synaptic rewiring is the cause for cortical remapping after a lesion. Recent two-photon laser imaging studies demonstrate that synaptic rewiring is persistent in the adult brain and is dramatically increased following brain lesions or after a loss of sensory input (cortical deafferentation). We use a recurrent neural network model to study the time course of synaptic rewiring following a peripheral lesion. For this, we represent axonal and dendritic elements of cortical neurons to model synapse formation, pruning and synaptic rewiring. Neurons increase and decrease the number of axonal and dendritic elements in an activity-dependent fashion in order to maintain their activity in a homeostatic equilibrium. In this study we demonstrate that synaptic rewiring contributes to neuronal homeostasis during normal development as well as following lesions. We show that networks in homeostasis, which can therefore be considered as adult networks, are much less able to compensate for a loss of input. Interestingly, we found that paused stimulation of the networks are much more effective promoting reorganization than continuous stimulation. This can be explained as neurons quickly adapt to this stimulation whereas pauses prevents a saturation of the positive stimulation effect. These findings may suggest strategies for improving therapies in neurologic rehabilitation.
目前尚不清楚，就突触重新布线而言，结构可塑性在多大程度上是损伤后皮质重新映射的原因。最近的双光子激光成像研究表明，突触重新布线在成人大脑中持续存在，并且在脑损伤后或感觉输入丧失（皮质传入神经阻滞）后显著增加。我们使用循环神经网络模型来研究外周损伤后突触重新布线的时间进程。为此，我们模拟皮质神经元的轴突和树突成分，以模拟突触形成、修剪和突触重新布线。神经元以活动依赖的方式增加和减少轴突和树突成分的数量，以维持其活动处于稳态平衡。在本研究中，我们证明突触重新布线在正常发育过程以及损伤后对神经元稳态有贡献。我们表明，处于稳态的网络，因此可被视为成熟网络，补偿输入损失的能力要弱得多。有趣的是，我们发现暂停刺激网络比持续刺激更有效地促进重组。这可以解释为神经元会迅速适应这种刺激，而暂停可防止正向刺激效果饱和。这些发现可能为改善神经康复治疗提供策略。
