To determine whether clustering of dynamic inhibitory synapses with dynamic spines were

merely a reflection of the dendritic distribution of inhibitory synapses Small Molecule Compound Library and spines, we performed nearest neighbor analysis between every monitored dynamic and stable inhibitory synapse and every dynamic and stable spine (Figure 5C). We found that inhibitory synapse changes occur in closer proximity to dynamic dendritic spines as compared to stable spines (K-S test, p < 2.0 × 10−6; Figure 5D). Conversely, dendritic spine changes occur in closer proximity to dynamic inhibitory synapses as compared to stable inhibitory synapses (K-S test, p < 2.0 × 10−4; Figure 5E). Interestingly, dendritic spine changes were not clustered with each other and indeed occurred with less proximity to neighboring dynamic spines as compared to stable spines (stable spines versus dynamic spines, K-S http://www.selleckchem.com/products/lee011.html test, p < 0.05; Figure 5F). We observed no difference in nearest neighbor distribution between dynamic inhibitory synapses and their dynamic or stable inhibitory counterparts (Figure 5G). These results demonstrate that dendritic spine-inhibitory synapse changes are spatially clustered along dendritic segments, whereas dendritic spine-dendritic spine changes and inhibitory synapse-inhibitory synapse changes are not. Clustered dynamics were the same for inhibitory shaft or spine synapses in relation to the nearest

dynamic dendritic spine (Figure S5B). We next asked how altering sensory experience through MD affects clustering of inhibitory synapse and dendritic spine changes. We found that clustering between dynamic inhibitory synapses and dendritic spines persisted during MD (Figure S5C) with a similar spatial distribution compared to control conditions (Figure S5D). We compared the frequency of clustered events during normal vision and MD by quantifying the number of inhibitory synapses and dendritic spine changes occurring within 10 μm of each other. MD increased the

frequency of clustered events from 0.013 ± 0.004 oxyclozanide to 0.020 ± 0.003 per μm dendrite (Wilcoxon rank-sum test, p < 0.05; Figure 5H). Since MD increases inhibitory synapse but not dendritic spine dynamics, we asked how an increase in clustered events could occur without a concurrent change in dendritic spine remodeling. We found that whereas the fraction of dynamic spines did not increase in response to MD (Figures 4B–4D), the fraction of dynamic spines participating in clustered events increased from 38.4% ± 9.0% to 59.0% ± 7.7% during MD (Wilcoxon rank-sum test, p < 0.05). A small fraction of spines in the SSEM were unaccounted for in the imaging. In all cases, these were z-projecting dendritic spines, obscured by the eYFP-labeled dendrite above or below. Generally, we find little or no image rotation along the x or y axis from session to session.