Neuropeptide modulation of microcircuits.

Neuropeptides provide functional flexibility to microcircuits, their inputs and effectors by modulating presynaptic and postsynaptic properties and intrinsic currents. Recent studies have relied less on applied neuropeptide and more on their neural release. In rhythmically active microcircuits (central pattern generators, CPGs), recent studies show that neuropeptide modulation can enable particular activity patterns by organizing specific circuit motifs. Neuropeptides can also modify microcircuit output indirectly, by modulating circuit inputs. Recently elucidated consequences of neuropeptide modulation include changes in motor patterns and behavior, stabilization of rhythmic motor patterns and changes in CPG sensitivity to sensory input. One aspect of neuropeptide modulation that remains enigmatic is the presence of multiple peptide family members in the same nervous system and even the same neurons.