Fig. 6
Paired mTORC1 and synaptic stimulation increases morphological volatility. (a-b) Representative images and example timecourses from spines sorted into categories of (a) “high volatility” (i.e. spines with changes spine head diameter > 200% in a single imaging timepoint) or (b) “low volatility” (i.e. spines that exhibit more gradual alterations in spine head diameter). Scale bar = 0.5 μm. (c) Scatter plot with marginal frequency histograms displaying the relationship between maximum change in head width during entire experiment (quantified as absolute percent difference from preceding timepoint) vs initial spine head diameter in μm. Each dot represents a single spine. Spines across all experimental parameters show in d-f included (n = 5756 spines). Excluding spines with head width smaller than 0.5um at minute zero (red shading) resulted in truncated data set with n = 5495 spines. (d) Cumulative probability distribution (and mean +/−SEM, inset) of the maximum single period change in head diameter (quantified as absolute percent difference from preceding timepoint) for groups as indicated. Pairing of low threshold synaptic stimulation with mTORC1 upregulation (Q64L+ 10 μM glycine) results in significantly enhanced ‘volatility’ of spine head diameter compared to all other experimental groups assessed. (ANOVA, F4,5490 = 13.956, p = 3.95e-11; eGFP n = 1267 spines, 10 μM Glycine n = 572 spines, 400 μM Glycine n = 1469 spines, RhebQ64L alone n = 1171 spines, RhebQ64L + 10 μM Glycine n = 1016 spines). * denotes significant difference from eGFP controls by Fisher LSD post hoc. (e) Cumulative probability distribution (and mean +/−SEM, inset) of the maximum single period change in head diameter for groups as in (d), separated by morphological type. * denotes significant difference from eGFP controls by Fisher LSD post hoc