Networks with lateral connectivity. III. Plasticity and reorganization of somatosensory cortex.
Networks with lateral connectivity. III. Plasticity and reorganization of somatosensory cortex.
复制标题
具有横向连接的网络。
DOI：
10.1152/jn.1996.75.1.217
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Gerstein,GL
中科院分区：
文献类型：
--
作者：
Xing,J;Gerstein,GL
1.用三层神经网络模型研究了大脑皮层已形成神经元群的皮层重组机制。2.模拟行为训练和皮层内微刺激(ICMS)诱发的大脑皮层动态变化。这两种操作都导致了神经元群的重组和刺激依赖的组装的形成。神经元的感受野和输入的皮质表征也发生了变化。许多反应微弱或沉默的神经元变得活跃起来。3.在模拟行为训练、ICMS诱导的动态变化、去传入或皮质损伤的情况下，考察了几种类型的学习模型。每个学习模型都最准确地再现了来自不同操作的实验数据的特征，这表明不止一种可塑性机制可能能够诱导皮质的动态变化。4.在皮肤或皮质刺激停止后，随着自发活动的继续，刺激依赖型集合体逐渐恢复为结构依赖型神经元群。然而，单个神经元之间的关系和许多神经元的身份并没有恢复到原来的状态。因此，在下一次出现时，相同的训练刺激序列将招募一组不同的神经元。5.我们还复制了几种典型的长期重建，这些重建是由皮质损伤、输入丢失和手指融合等病理操作引起的。6.综上所述，采用Hebbian型侧向连接的塑性规则，该网络模型能够再现大部分皮质重组实验的特征。我们认为，皮层可塑性改变的一个重要机制是与强同步局部化输入的接收有关的临时组装的形成。在去除刺激后，这种依赖于刺激的组装可以通过自发活动来分解。
1. Mechanisms underlying cortical reorganizations were studied using a three-layered neural network model with neuronal groups already formed in the cortical layer. 2. Dynamic changes induced in cortex by behavioral training or intracortical microstimulation (ICMS) were simulated. Both manipulations resulted in reassembly of neuronal groups and formation of stimulus-dependent assemblies. Receptive fields of neurons and cortical representation of inputs also changed. Many neurons that had been weakly responsive or silent became active. 3. Several types of learning models were examined in simulating behavioral training, ICMS-induced dynamic changes, deafferentation, or cortical lesion. Each learning model most accurately reproduced features of experimental data from different manipulations, suggesting that more than one plasticity mechanism might be able to induce dynamic changes in cortex. 4. After skin or cortical stimulation ceased, as spontaneous activity continued, the stimulus-dependent assemblies gradually reverted into structure-dependent neuronal groups. However, relationships among individual neurons and identities of many neurons did not return to their original states. Thus a different set of neurons would be recruited by the same training stimulus sequence on its next presentation. 5. We also reproduced several typical long-term reorganizations caused by pathological manipulations such as cortical lesions, input loss, and digit fusion. 6. In summary, with Hebbian plasticity rules on lateral connections, the network model is capable of reproducing most characteristics of experiments on cortical reorganization. We propose that an important mechanism underlying cortical plastic changes is formation of temporary assemblies that are related to receipt of strongly synchronized localized input. Such stimulus-dependent assemblies can be dissolved by spontaneous activity after removal of the stimuli.