Chondroitin sulphate proteoglycan-based perineuronal net establishment is largely activity-independent in chick visual system.

Extracellular matrix components consisting of large aggregating chondroitin sulphate proteoglycans accumulate around neuronal perikarya to establish perineuronal nets. These perineuronal nets surround subpopulations of neurons in many vertebrates including man. In chickens, perineuronal nets show very fast matrix maturation after hatching which is probably due to the rapid establishment of neuronal morphology and immediate functional and behavioural performance of the animals. In mammals, maturation of extracellular matrix including perineuronal nets largely depends upon specific afferent activation. The present study shows that extracellular matrix maturation in mesencephalic, diencephalic and telencephalic visual centers of chicks tectofugal system is not principally determined by light activation. Perineuronal nets show an equally developed phenotypic character on monocularly light deprived animals in all investigated brain regions. Results suggest that establishment of extracellular matrix and perineuronal nets are largely activity-independent in the investigated precocial bird.