Geman S, Miller M
J Appl Physiol. 1976 Dec;41(6):931-8. doi: 10.1152/jappl.1976.41.6.931.
A mathematical model of the medullary respiratory oscillator, composed of two mutually inhibiting populations (inspiratory and expiratory) of computer-simulated neurons, is presented. Each population consists of randomly interconnected subpopulations of excitatory and inhibitory neurons, is presented. Each population consists of randomly interconnected subpopulations of excitatory and inhibitory neurons. Neuronal coupling is such that either the inspiratory or expiratory population alone is capable of cyclic activity. Weak inhibitory connections between inspiratory and expiratory populations provide satisfactory reciprocating activity independent of the natural frequency of either population alone. Initiation and persistence of rhythmic activity is dependent on a diffused noncyclic excitatory input. Vagal discharge, simulated by phasic inhibition of inspiratory neurons, results in increased respiratory frequency with decreased inspiratory activity. In the absence of simulated vagal discharge, uniform facilitation of synaptic connections increases averaged activities of inspiratory and expiratory populations, with minor effect on frequency. In the presence of simulated vagal discharge, facilitation of synaptic connections increases both frequency and amplitude. The simulated effects of synaptic facilitation, with and without vagal discharge, mimic the physiological response to CO2 in the intact and vagotimized animal.
本文提出了一种延髓呼吸振荡器的数学模型，该模型由两个相互抑制的计算机模拟神经元群体（吸气和呼气群体）组成。每个群体由兴奋性和抑制性神经元的随机互连亚群组成。神经元耦合使得仅吸气或呼气群体就能产生周期性活动。吸气和呼气群体之间的弱抑制性连接提供了令人满意的往复活动，而与任一群体单独的固有频率无关。节律性活动的启动和持续取决于弥散性非周期性兴奋性输入。通过对吸气神经元的相位性抑制来模拟迷走神经放电，会导致呼吸频率增加且吸气活动减少。在没有模拟迷走神经放电的情况下，突触连接的均匀易化会增加吸气和呼气群体的平均活动，对频率影响较小。在存在模拟迷走神经放电的情况下，突触连接的易化会增加频率和幅度。有无迷走神经放电时突触易化的模拟效应，模拟了完整动物和迷走神经切断动物对二氧化碳的生理反应。
