Spine-mitochondria association and its contribution to AMPAR trafficking. (a) A scoring system to assign different spine-mito scores to each spine. The color image on the left shows a merged image of SEP-GluR1 highlighted spines (green) and mitochondria (red). Different scores (0-3) were given to spines depending on their association and proximity to a mitochondrion. The schematic diagram illustrates the scoring criteria, together with examples in magnified view. Analysis of several hundreds of spines from at least three batches of experiments was performed for each condition and data are summarized in the bar graph in (b). Spines receiving spine-mito scores of 1-3 were considered to be associated with mitochondria and used for calculating the percentage of spines associated with mitochondria (c). Single asterisk: p < 0.05; double asterisk: p < 0.005; triple asterisks: p < 0.0005 (comparing to the corresponding control group, Student's t-test).