Fig. 3. Spine morphometric parameters are largely uncorrelated, while head size and neck width, but not neck length, exhibit multiplicative dynamics.

(A) Features assessed of stable spines are head size, spine neck length, and neck width. (B to D) Histogram of the logarithmic spine head sizes (B), spine neck lengths (C), and neck width (D). (B and D) The log₁₀ data are normally distributed indicated by a Gaussian fit (black line). (E to G) Correlation between spine parameters. Spine head size (E) and neck width (F) as a function of neck length, and head size as function of neck width (G); linear regression (black) and Pearson’s correlation coefficient r. (H to J) The angle between the dendrite and the spine neck (α, neck-dendrite angle) (I) and between the neck and the spine head (β, neck-head angle) (J) is measured. (K) Principal components (PC) analysis of five morphological parameters. (B to G and I to K) All data of all time points pooled. Number of analyzed spines are listed in table S1.