TISSUE-PLASMINOGEN ACTIVATOR MEDIATES REVERSE OCCLUSION PLASTICITY INVISUAL-CORTEX

Preventing visual input to one eye (monocular deprivation) in early po stnatal development reduces cortical responses to stimulation of the d eprived eye, with a significant loss of thalamocortical connections. T hese effects are reversible by opening the deprived eye and closing th e previously open eye (reverse occlusion). We show that intracortical blockade of tissue plasminogen activator or plasmin selectively preven ts recovery of cortical function and thalamic neuron size during rever se occlusion, without affecting the monocular deprivation response. Th erefore, a proteolytic cascade consisting of plasmin generated by tiss ue plasminogen activator may selectively mediate reverse-occlusion-ind uced cortical plasticity, perhaps via structural remodeling of axons.