AbstractThe formation of neuronal circuitry involves a period of activity‐dependent fine‐tuning and maturation of the connectivity, during which some of the nascent synapses are strengthened and others are eliminated. Many of the mechanisms utilized in this process are developmentally downregulated and replaced with synaptic machinery typical of adult‐type transmission. The kainate‐type of ionotropic glutamate receptors (KARs) modulate transmission and excitability of the neuronal networks in a complex manner, and thereby contribute to generation of patterned activity critical for plasticity and information processing. The expression, activation, and signaling of KARs is altered during early postnatal development and it is becoming evident that these receptors have specific functions during synapse maturation. In particular, developmentally restricted functions have been described for presynaptically located KARs in both areas CA3 and CA1 of the hippocampus. Although the exact mechanisms and receptor subunits responsible for these effects are still largely unclear, it is evident that KARs regulate synapse dynamics and plasticity in the neonatal brain and might be critically important in linking neuronal activity to morphogenesis at immature synapses. WIREs Membr Transp Signal 2012, 1:45–55. doi: 10.1002/wmts.3For further resources related to this article, please visit the WIREs website.