The many faces of inhibitory plasticity: Adding flexibility to cortical circuits throughout development

Neocortical circuits are highly interconnected networks of excitatory and inhibitory neurons. During postnatal development the connectivity and strength of excitatory and inhibitory synapses and the intrinsic properties of each neuron type sculpt the overall level of excitability of the circuit and support network function. Healthy neural circuits are characterized by a high sensitivity to changes in environmental stimuli and a finely tuned dynamic range. A balanced combination of excitatory and inhibitory inputs endows cortical circuits with the ability to maintain a dynamically stable level of excitability despite changes in sensory inputs. How this dynamically stable state is achieved during development is still matter of debate. In the past few decades, our knowledge of cortical neurogenesis, layer differentiation and circuit refinement has expanded dramatically. While most of the research has focused on the regulation of excitatory neocortical neurons, it is now accepted that inhibitory circuits contribute substantially to the achievement and maintenance of cortical circuit stability and function. Here we will focus on recent advancements in our understanding of the postnatal development of local inhibitory circuits and their role in the maintenance of cortical circuit excitability and stability.