(B) WT and MPS-IIIA hippocampal neurons (DIV14) were transfected with v-Glut1-pHluorin-mCherry plasmid and synaptic recycling was evaluated by the fluorescence change of the probe from 80-100 individual boutons (taken from 4-5 coverslips for each group). Fluorescence intensity was quantified at each bouton during KCl perfusion, normalized to the fluorescence value obtained upon rapid alkalization (NH4Cl perfusion) and expressed as ∆fluorescence (normalized to baseline; ΔFKCl/ΔF NH4Cl). Values were displayed both as fluorescence traces (means ± s.e.m. at each time frame) and maximum fluorescence after KCl perfusion (means ± s.e.m.). Representative panels on the right show the fluorescence intensity change in control neurons (WT). Pseudo-colour was applied to better reveal fluorescence changes.Note that NH4Cl alkalinizes all vesicles revealing the total (recycling + resting) pool in neuronal cells analyzed. 