MiR-29 coordinates age-dependent plasticity brakes in the adult visual cortex (vol 21, e50431, 2020)

Visual cortical circuits show profound plasticity during early life and are later stabilized by molecular brakes limiting excessive rewiring beyond a critical period. The mechanisms coordinating the expression of these factors during the transition from development to adulthood remain unknown. We found that miR-29a expression in the visual cortex dramatically increases with age, but it is not experience-dependent. Precocious high levels of miR-29a blocked ocular dominance plasticity and caused an early appearance of perineuronal nets. Conversely, inhibition of miR-29a in adult mice using LNA antagomirs activated ocular dominance plasticity, reduced perineuronal nets, and restored their juvenile chemical composition. Activated adult plasticity had the typical functional and proteomic signature of critical period plasticity. Transcriptomic and proteomic studies indicated that miR-29a manipulation regulates the expression of plasticity brakes in specific cortical circuits. These data indicate that miR-29a is a regulator of the plasticity brakes promoting age-dependent stabilization of visual cortical connections.

Automated summary

Research has shown that the expression of miR-29a in the visual cortex increases dramatically with age but is not experience-dependent. Precocious high levels of miR-29a can block ocular dominance plasticity and cause an early appearance of perineuronal nets, while inhibiting miR-29a in adult mice can activate ocular dominance plasticity and reduce perineuronal nets. This suggests that miR-29a plays a role in regulating the plasticity brakes that promote age-dependent stabilization of visual cortical connections.