G. Representative western blots from whole extracts of organotypic slices incubated in ACSF (untreated; 'baseline'), treated with 20 µM NMDA for 5 minutes ('cLTD') or treated with 20 µM NMDA for 5 minutes and allowed to recover in plain ACSF for 10 minutes ('washout'). Blots were probed for pSer21/9 GSK3α/β, total GSK3α/β, pSer845 GluA1, and total GluA1. H. Quantification of experiments as those shown in G. Error bars represent SEM and statistical significance was calculated according to the Mann-Whitney U test. N = 4 independent experiments for all conditions. Asterisks (**) denote P < 0.01. 