Microscale AMPAR Reorganization and Dynamics of the Postsynaptic Density

Principles of FRAP experiment with AMPARs. Left, Scheme illustrating photobleaching and recovery of a whole synapse (top, Full Bleaching) versus half of a synapse (bottom, Partial Bleaching). Before the bleach event, fluorescent AMPARs can be viewed on the synaptic surface (A, green dots, baseline). Immediately after photobleaching, AMPARs are no longer fluorescent (B, gray dots, total bleaching) and then fluorescence gradually recovers (C, green and gray dots, recovery) as unbleached AMPARs move into the bleached area. Note that, under basal conditions, full bleaching and partial bleaching result with the same recovery graph (right, blue line and dashed red line, respectively). When intrasynaptic mobility of AMPARs is increased (e.g., after glutamate application), there is a stronger increase in recovery following partial bleaching (right, solid red line).