Fig. 4

Genetic up- or down-regulation of mTORC1 activity is not sufficient to increase spine head size on its own. (a) Representative images of dendritic regions from hippocampal neurons 24Hrs after expression of either eGFP alone (n = 940 spines across 12 cells) or alongside either a constitutively active version of the positive upstream regulator RhebQ64L (n = 929 spines across 15 cells) or the complex of inhibitory mTORC1 effectors TSC1/2 (n = 509 spines across 10 cells). Scale bar =10 μm. (b) Cumulative probability distribution and mean (+SEM) values (inset) for spine head width in neurons with genetic alterations in mTORC1 signaling as indicated. *p < 0.05 relative to control cells expressing eGFP alone. (c) Mean (+/−SEM) values of spine head width in groups as indication, broken up according to morphological subtype. 24 h of genetically-mediate up- down-regulation of mTORC1 activity produced a moderate but significant decrease in dendritic head width, primarily observed in stubby and flat morphological types. *p < 0.05 relative to control cells expressing eGFP alone. (d) Scatter plots comparing spine head width and protrusion length for cells expression eGFP (left), RhebQ64L (middle) or TSC1/2 (right)