Extracellular matrix inhibits structural and functional plasticity of dendritic spines in the adult visual cortex

• Published in: Nature communications 2013-02, Vol.4 (1), p.1484, Article 1484
• Main Authors: de Vivo, L., Landi, S., Panniello, M., Baroncelli, L., Chierzi, S., Mariotti, L., Spolidoro, M., Pizzorusso, T., Maffei, L., Ratto, G.M.
• Format: Article
• Language: English
• Subjects: 631/378/2597/2599; 631/378/2617/2618; 631/80/84/750; Aging - physiology; Animals; Brain; Chondroitin ABC Lyase - pharmacology; Chondroitin sulfate; Chondroitin Sulfate Proteoglycans - metabolism; Correspondence; Dendritic Spines - drug effects; Dendritic Spines - physiology; Electrodes; Evoked Potentials, Visual - drug effects; Extracellular matrix; Extracellular Matrix - drug effects; Extracellular Matrix - metabolism; Fluorescence; Green Fluorescent Proteins - metabolism; Humanities and Social Sciences; Hypotheses; Long-Term Potentiation - drug effects; Male; Mice; Mice, Inbred C57BL; Morphology; Motility; Movement - drug effects; multidisciplinary; Neuronal Plasticity - drug effects; Neuronal Plasticity - physiology; Science; Science (multidisciplinary); Spinal cord; Visual Cortex - drug effects; Visual Cortex - growth & development; Visual Cortex - physiology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms2491

Brain cells are immersed in a complex structure forming the extracellular matrix. The composition of the matrix gradually matures during postnatal development, as the brain circuitry reaches its adult form. The fully developed extracellular environment stabilizes neuronal connectivity and decreases cortical plasticity as highlighted by the demonstration that treatments degrading the matrix are able to restore synaptic plasticity in the adult brain. The mechanisms through which the matrix inhibits cortical plasticity are not fully clarified. Here we show that a prominent component of the matrix, chondroitin sulfate proteoglycans (CSPGs), restrains morphological changes of dendritic spines in the visual cortex of adult mice. By means of in vivo and in vitro two-photon imaging and electrophysiology, we find that after enzymatic digestion of CSPGs, cortical spines become more motile and express a larger degree of structural and functional plasticity. Neuronal connectivity in the mature brain is stabilized by the extracellular matrix. This study shows that degradation of chondroitin sulfate proteoglycans in the matrix increases connectivity in the adult cortex by causing a large increase in motility and functional plasticity of dendritic spines.