Neuroscience Forefront ReviewExperience-dependent plasticity of visual cortical microcircuits

- Plasticity is highly layer- and cell-type specific in cortical microcircuits.
- Non-competitive mechanisms are central to cortical map plasticity.
- Cortical plasticity has different functions and mechanisms in adulthood.
- Inhibition plays both a permissive and instructive role in cortical plasticity.
- Structural and functional plasticity occur simultaneously in the living cortex.

The recent decade testified a tremendous increase in our knowledge on how cell-type-specific microcircuits process sensory information in the neocortex and on how such circuitry reacts to manipulations of the sensory environment. Experience-dependent plasticity has now been investigated with techniques endowed with cell resolution during both postnatal development and in adult animals. This review recapitulates the main recent findings in the field using mainly the primary visual cortex as a model system to highlight the more important questions and physiological principles (such as the role of non-competitive mechanisms, the role of inhibition in excitatory cell plasticity, the functional importance of spine and axonal plasticity on a microscale level). I will also discuss on which scientific problems the debate and controversies are more pronounced. New technologies that allow to perturbate cell-type-specific subcircuits will certainly shine new light in the years to come at least on some of the still open questions.