Cortical neurons can adjust synaptic strength to compensate for changes in external drive, both in vitro and in vivo. We reported that activity blockade increased the accumulation of native AMPA receptors detected with immunolabeling, accounting for the increase in quantal amplitude induced by activity blockade (2003 SFN abstract). To date, studies of synaptic scaling have not been able to follow changes in individual neurons or postsynaptic sites. To investigate the role of receptor accumulation in individual neurons and postsynaptic sites, we performed time-lapse imaging of neurons that expressed EGFP-GluR2. The transfected cell showed distinct puncta and diffuse dendritic fluorescence. These puncta were well colocalized with surface anti-EGFP staining and anti-GluR2 staining, indicating EGFP-GluR2 was correctly trafficked to postsynaptic site. Furthermore, EGFP-GluR2 fluorescence and the amount of surface EGFP were well correlated. To select synaptically localized EGFP-GluR2 more efficiently, we co-tran...