Fricke R A
Brain Res. 1984 Nov 19;322(1):139-43. doi: 10.1016/0006-8993(84)91193-4.
During posthatching development, transmission becomes substantially reduced at monosynaptic electrical synapses between tactile afferents and the command neuron for caudal tailflip escape responses of the crayfish. The effectiveness of a parallel disynaptic pathway to the same command neuron is unaltered during posthatching growth. In small crayfish both the monosynaptic and disynaptic sensory pathways can elicit command cell action potentials. At this stage, the characteristics of the tailflip neural circuit are evidently controlled by the shorter latency, non-labile monosynaptic pathway. Consequently, tailflips can be reliably elicited in young crayfish, even at brief (2 s) interstimulus intervals. Tailflip responses of large, older crayfish are known to habituate when tactile stimuli are repeated at intervals up to 5 min. This decline in behavioral responsiveness is presumed to be mediated by low frequency synaptic depression (LFD) at first-order synapses of the disynaptic pathway. The lability of these synapses does not change during post-hatching development. Weakening of the monosynaptic pathway may be caused by command cell growth during posthatching development.
在孵化后发育过程中，小龙虾触觉传入神经元与负责尾部后翻逃避反应的指令神经元之间的单突触电突触传递显著减少。在孵化后生长过程中，通向同一指令神经元的平行双突触通路的有效性未发生改变。在小型小龙虾中，单突触和双突触感觉通路都能引发指令细胞动作电位。在此阶段，尾部后翻神经回路的特征显然由潜伏期较短、不稳定的单突触通路控制。因此，即使在短（2秒）的刺激间隔下，幼体小龙虾也能可靠地引发尾部后翻。已知当以长达5分钟的间隔重复触觉刺激时，大型、成熟小龙虾的尾部后翻反应会产生习惯化。行为反应性的这种下降据推测首先是由双突触通路一级突触处的低频突触抑制（LFD）介导的。这些突触的不稳定性在孵化后发育过程中不会改变。单突触通路的减弱可能是由孵化后发育过程中指令细胞的生长引起的。
