The Balance between
Stability and Plasticity in the Neuromodulation and
Growth of Neural Circuits
Neuronal circuits must maintain stable
function throughout the lifetime 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 synaptic strength and intrinsic
cellular excitability. I described 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 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 intrinsic
membrane properties and inhibitory synapses.
