Wegner W, Steffens H, Gregor C, Wolf F, Willig KI
Synaptic plasticity underlies long-lasting structural and functional changes to brain circuitry and its experience-dependent remodeling can be fundamentally enhanced by environmental enrichment. It is unknown, however, whether and how environmental enrichment alters the morphology and dynamics of individual synapses. Here, we present a virtually crosstalk free, two-color in vivo STED microscope to simultaneously superresolve the dynamics of the postsynaptic density protein PSD95 and spine geometry. With environmental enrichment, the size distribution of PSD95 and spine head sizes were narrower than in controls, indicating that synaptic strength is set more precisely with environmental enrichment. Spine head geometry and PSD95 assemblies were highly dynamic exhibiting multiplicative size changes. With environmental enrichment, the topography of PSD95 nanoorganization was more dynamic and the magnitude of reorganization increased systematically with time. Thus, two-color in vivo time-lapse imaging of synaptic nanoorganization uncovers a unique synaptic nanodynamics associated with the enhanced learning capabilities under environmental enrichment.