Cortical dendritic spine development and plasticity: insights from in vivo imaging

Dendritic spines are the postsynaptic sites of most excitatory synapses in the cerebral cortex. Their morphology and density change throughout life, reflecting the maturation and reorganization of excitatory circuits. The development of in vivo two-photon microscopy has enabled the monitoring of the same dendritic spines over time during different developmental periods. In this review we focus on recent in vivo imaging studies in rodents that have revealed cell type-specific and region-specific structural dynamics of dendritic spines. We also discuss how the contributions of local inhibitory neurons and long-distance excitatory and neuromodulatory inputs to the cortex influence dendritic spine development and dynamics. Such studies will facilitate our understanding of how environmental factors and experiences affect cortical synapse development.