锥体神经元的连接模式对突触后局部电位的依赖

脑皮层的功能连接模式与突触可塑性密切相关,受突触空间分布和刺激模式等多种因素的影响。尽管越来越多的证据表明突触可塑性不仅受突触后动作电位而且还受突触后局部树突电位的影响,但是目前尚不清楚神经元的功能连接模式是否和怎样依赖于突触后局部电位的。为此,本文建立了一个无需硬边界设置的、突触后局部膜电位依赖的可塑性模型。该模型具有突触强度的自平衡能力并且能够再现多种突触可塑性实验结果。基于该模型对两个锥体神经元的功能连接模式进行仿真的结果表明,当突触后局部电位都处于亚阈值时两个神经元无功能连接,如果一个神经元的突触后膜电位高于阈值电位则产生向该神经元的单向连接,当两个神经元的突触后膜电位都超过阈值电位时则产生双向连接,说明突触后局部膜电位分布是神经元功能连接模式形成的关键。研究结果加深了神经网络连接模式形成机制的理解,对学习和记忆的研究具有重要意义。

Dependence of connection pattern of pyramidal neurons on postsynaptic local potential

The functional connection pattern of cerebral cortex is closely related to synaptic plasticity and affected by many factors such as synaptic spatial distribution and stimulation pattern. Although there is increasing evidence that synaptic plasticity is influenced not only by postsynaptic action potentials but also by postsynaptic local dendrite potentials, it is not clear whether and how the pattern of functional connections of neurons depends on postsynaptic local potentials. To this end, a postsynaptic local membrane potential-dependent plasticity model was established without hard boundary setting. The model has the self-balancing ability of synaptic strength and can reproduce the experimental results of various forms of synaptic plasticity. Based on the model,simulation of connection patterns of two pyramidal neurons was performed,and results show that when the postsynaptic local potential was at the threshold function,the two neurons had no connection; if the postsynaptic membrane potential of a neuron was higher than the threshold voltage, one-way connection to the neuron was produced; when the postsynaptic membrane potential was higher than the threshold voltage, bidirectional connection produced. It shows that postsynaptic potential distribution is the key of function connection pattern formation of neurons. The research results deepen the understanding of the formation mechanism of neural network connection pattern and are of great significance to the study of learning and memory.