Gonzalez-Islas Carlos, Wenner Peter
Department of Physiology, Emory University, School of Medicine, Atlanta, Georgia 30322, USA.
Neuron. 2006 Feb 16;49(4):563-75. doi: 10.1016/j.neuron.2006.01.017.
Spontaneous network activity (SNA) has been described in most developing circuits, including the spinal cord, retina, and hippocampus. Despite the widespread nature of this developmental phenomenon, its role in network maturation is poorly understood. We reduced SNA in the intact embryo and found compensatory increases in synaptic strength of spinal motoneuron inputs. AMPAergic miniature postsynaptic current (mPSC) amplitude and frequency increased following the reduction of activity. Interestingly, excitatory GABAergic mPSCs also increase in amplitude through a process of synaptic scaling. Finally, the normal modulation of GABAergic mPSC amplitude was accelerated. Together, these compensatory responses appear to increase the excitability of the cord and could act to maintain appropriate SNA levels, thus demonstrating a distinct functional role for synaptic homeostasis. Because spontaneous network activity can regulate AMPAergic and GABAergic synaptic strength during development, SNA is likely to play an important role in a coordinated maturation of excitatory and inhibitory synaptic strength.
在包括脊髓、视网膜和海马体在内的大多数发育中的神经回路中，都有自发网络活动（SNA）的描述。尽管这种发育现象很普遍，但其在网络成熟过程中的作用却知之甚少。我们在完整胚胎中降低了SNA，发现脊髓运动神经元输入的突触强度出现代偿性增加。在活动减少后，AMPA能微小突触后电流（mPSC）的幅度和频率增加。有趣的是，兴奋性GABA能mPSC的幅度也通过突触缩放过程而增加。最后，GABA能mPSC幅度的正常调节加快。这些代偿反应共同作用，似乎增加了脊髓的兴奋性，并可能起到维持适当SNA水平的作用，从而证明了突触稳态的独特功能作用。由于自发网络活动在发育过程中可以调节AMPA能和GABA能突触强度，SNA可能在兴奋性和抑制性突触强度的协调成熟中发挥重要作用。
