Neuronal Network Stability Built on Mechanisms of Intrinsic and Synaptic Plasticity
Neuronal circuits must maintain stable function throughout the life-time of the animal although all of the receptors and channels necessary for signaling are constantly turning over. Because the activity of single neurons depends not on the number of any single ion channel, but on the number and kinds of all its channels, stable electrical excitability requires the coordinate regulation of the conductance densities of all channels. Likewise, network activity requires the coordinate regulation of both synaptic strength and intrinsic cellular excitability. I will describe a series of experimental and computational studies that address the problem of how cellular and circuit homeostasis occurs in the face of all of the mechanisms for cellular plasticity. The experimental system we use is the crustacean stomatogastric nervous system, which produces rhythmic motor patterns that depend both on the presence of bursting neurons and a large number of inhibitory connections. Therefore, the self-assembly and maintenance of stable circuit behavior requires the coordinate tuning of both intrinsic membrane properties and inhibitory synapses.