Fig. 6. Regulation of the topological distribution of extra-synaptic AMPARs in conditions of synaptic plasticity. (A) Surface proportion of the detected AMPARs, S(r), as in Figure 1G, but in the presence of glutamate. (B) The difference (%) between Figure 1G and (D) reveals a significant increase of AMPARs in the presence of glutamate in an annulus ∼400–800 nm from the center of the synapses defined later as the ‘juxtasynaptic region’. (C) Example of a juxtasynaptic trajectory and of the different regions defined in the plasma membrane of the neurons with respect to synaptic staining. Scale bar = 500 nm. (D) Ratio of juxtasynaptic to extra-synaptic AMPARs in the six different conditions shown in Figures 4A and 5A. Glutamate-induced LTD doubles the proportion of juxtasynaptic AMPARs (P < 0.001 that the Glut value is different from the five others, Student’s t-test) and a 40% decrease in the proportion of juxtasynaptic receptors after 40 min of Bic/Gly is found (P < 0.05 that the Bic/Glyc40 value is different from the five others, Student’s t-test).