Physiological study of synchronous firing activity in insect neurosecretory cell systems

在家蚕的大脑中，有四对神经分泌细胞产生家蚕毒素，这是一种与胰岛素相关的肽。对产毒细胞的电信号进行了鉴定，并分析了产毒细胞在整个蛹期的短期和长期活动模式。细胞的活动模式以周期性地发放一连串动作电位为特征。电活动的周期性依赖于温度，2 6℃时的平均周期±SD为34.7±4.8min。大脑半球的四个细胞在功能上是不同的：单个细胞具有特定的活动幅度和节律，因此表明一个细胞的超传统活动节律源于其固有的起搏器活动。电活动无明显的昼夜振荡。日活动模式在蛹期早期(第2天或第3天)达到最大。研究人员研究了四对具有超常爆发节律的家蚕毒素产生细胞之间的放电相关性。对两个同时活跃的细胞之间的棘波活动的交叉相关分析通常显示出放电的显著相关性：一个细胞的棘波有20%-50%在另一个细胞的棘波发射之前或之后的0.2 S内发射。神经分泌细胞之间相互的、兴奋性的通信使这组细胞成为一个弱耦合的多振子系统，可能产生其激素的脉动释放模式，这似乎是维持激素活动的有效的时间模式。

There are four pairs of neurosecretory cells producing bombyxin, an insulin-related peptide, in the brain of Bombyx mori. Electrical signals of the bombyxin-producing cells were identified and short-and long-term activity patterns of the cells throughout the pupal period were analyzed. Activity pattern of the cells was characterized by periodic discharges of a volley of action potentials. Periodicity of the electrical activity depended on the temperature and mean±SD of periods was 34.7±4.8 min at 26℃. Four cells in a brain hemisphere were functionally heterogeneous : individual cells had specific activity amplitudes and rhythms, thereby suggesting that an ultradian activity rhythm of a cell originates from its intrinsic pacemaker activity. There was no significant diel (circadian) oscillation in the electrical activity. Daily activity patterns had a maximum at an early stage (day-2 or 3) of pupal period. Firing correlations were examined among four pairs of bombyxin-producing cells with an ultradian bursting rhythm. Cross-correlation analyses of spiking activities between pairs of simultaneously active cells usually revealed a significant correlation of firings : 20-50% of spikes of a cell fired within 0.2 s before or after the other cell's spikes fired. The mutual, excitatory communication among neurosecretory cells make the set of cells a weakly coupled multi-oscillator system that may generates a pulsatile release pattern of their hormone that seems to be an efficient temporal pattern for maintaining hormonal actions.