Figure 1:

LTP enhances synaptogenesis at P15 but stalls spine outgrowth in adults. A) 3DEMs of dendrites from oblique dendrites in s. radiatum of hippocampal area CA1 at P15 representing the 50^th percentile rank. Spine density in the 2-hour (2h) control is less than (red <) the 2h LTP condition. B) Quantification of spine density (spines/ μm) length of dendrite in s. radiatum of perfusion-fixed hippocampus (PF), and after 5 minutes (5’), 30’, and 2 hr in the control or LTP conditions. C) 3DEMs of dendrites from adult hippocampal s. radiatum representing the 50^th percentile rank. D) Plots show spine density in the 2h control is greater than (>) in the 2h LTP condition. Comparing PF between ages in B and D reveals natural age-dependent synaptogenesis. In all graphs, data were controlled for spine head diameter (HD). The LTP effects were not evident at 5 or 30 minutes; hence, these data are not plotted here, for simplicity, but they are available in the original publications. (Yellow – dendrite, green – smooth endoplasmic reticulum, red – excitatory postsynaptic density surface area. Gray asterisks indicate significant (p<0.05) differences between the indicated condition and PF; red asterisks show significant LTP effects. The medium blue asterisk in D, shows significant differences between time points for small spines. Adapted from Bourne and Harris, 2011; Bell et al., 2014; Watson et al., 2016; Kulik et al., 2019).