Szücs A, Elson R C, Rabinovich M I, Abarbanel H D, Selverston A I
Institute for Nonlinear Science, Scripps Institution of Oceanography, University of California, San Diego, California 92093-0402, USA.
J Neurophysiol. 2001 Apr;85(4):1623-38. doi: 10.1152/jn.2001.85.4.1623.
Periodic current forcing was used to investigate the intrinsic dynamics of a small group of electrically coupled neurons in the pyloric central pattern generator (CPG) of the lobster. This group contains three neurons, namely the two pyloric dilator (PD) motoneurons and the anterior burster (AB) interneuron. Intracellular current injection, using sinusoidal waveforms of varying amplitude and frequency, was applied in three configurations of the pacemaker neurons: 1) the complete pacemaker group, 2) the two PDs without the AB, and 3) the AB neuron isolated from the PDs. Depending on the frequency and amplitude of the injected current, the intact pacemaker group exhibited a wide variety of nonlinear behaviors, including synchronization to the forcing, quasiperiodicity, and complex dynamics. In contrast, a single, broad 1:1 entrainment zone characterized the response of the PD neurons when isolated from the main pacemaker neuron AB. The isolated AB responded to periodic forcing in a manner similar to the complete pacemaker group, but with wider zones of synchronization. We have built an analog electronic circuit as an implementation of a modified Hindmarsh-Rose model for simulating the membrane potential activity of pyloric neurons. We subjected this electronic model neuron to the same periodic forcing as used in the biological experiments. This four-dimensional electronic model neuron reproduced the autonomous oscillatory firing patterns of biological pyloric pacemaker neurons, and it expressed the same stationary nonlinear responses to periodic forcing as its biological counterparts. This adds to our confidence in the model. These results strongly support the idea that the intact pyloric pacemaker group acts as a uniform low-dimensional deterministic nonlinear oscillator, and the regular pyloric oscillation is the outcome of cooperative behavior of strongly coupled neurons, having different dynamical and biophysical properties when isolated.
采用周期性电流刺激来研究龙虾幽门中央模式发生器（CPG）中一小群电耦合神经元的内在动力学。该神经元群包含三个神经元，即两个幽门扩张肌（PD）运动神经元和前爆发神经元（AB）中间神经元。使用不同幅度和频率的正弦波形进行细胞内电流注入，应用于起搏器神经元的三种配置：1）完整的起搏器组；2）不含AB的两个PD；3）与PD分离的AB神经元。根据注入电流的频率和幅度，完整的起搏器组表现出多种非线性行为，包括与刺激同步、准周期性和复杂动力学。相比之下，当与主要起搏器神经元AB分离时，PD神经元的反应表现为单一、宽泛的1:1夹带区。分离的AB对周期性刺激的反应方式与完整的起搏器组相似，但同步区更宽。我们构建了一个模拟电子电路，作为修改后的Hindmarsh-Rose模型的实现，用于模拟幽门神经元的膜电位活动。我们对这个电子模型神经元施加与生物学实验中相同的周期性刺激。这个四维电子模型神经元再现了生物幽门起搏器神经元的自主振荡放电模式，并且它对周期性刺激表现出与生物对应物相同的静态非线性反应。这增加了我们对该模型的信心。这些结果有力地支持了这样一种观点，即完整的幽门起搏器组作为一个统一的低维确定性非线性振荡器起作用，并且规则的幽门振荡是强耦合神经元协同行为的结果，这些神经元在分离时具有不同的动力学和生物物理特性。
