Spontaneous Correlated Activity in Developing Neural Circuits

This minireview highlights several interesting functional properties common to three very different developing neural circuits: retina, spinal cord, and hippocampus. All three generate spontaneous action potentials during development. Although the structure of spontaneous activity differs in detail, they share a global or "macroscopic" activity pattern: the spontaneous activity consists of rhythmic bursts of action potentials that are correlated across tens to hundreds of cells and occur with a periodicity on the order of minutes. I propose that these similar properties arise from two general organizing principles: (1) highly interconnected excitatory synapses may be responsible for generating the rhythmic activity, and (2) homeostatic mechanisms may act to regulate the overall level of network activity. Last, I suggest a role for macroscopic aspects of these patterns in activity-dependent development.