Figure 6

Relationships between spine size and the location of presynaptic cells. (A) The soma of the postsynaptic neuron represents the center of the three dimensional coordinates. The presynaptic soma (x_pre, y_pre, z_pre), the innervated spine (x_sp, y_sp, 0), and their projections in the XY and XZ planes are shown. (B) XY-plane-projected distribution of presynaptic neurons (x_pre, y_pre) and the spines they innervated (x_sp, y_sp). Black, blue, orange, and red closed circles represent cells innervating spines of sizes 0-0.1 μm³ (black open circles), 0.1-0.2 μm³ (blue open circles), 0.2-0.3 μm³ (orange open circles), and >0.3 μm³ (red open circles), respectively. (C) Histograms of the lateral distance between the postsynaptic and presynaptic somata (left), $\sqrt{x_{pre}{}^2+z_{pre}{}^2}$; the lateral distance between the dendritic spine and the presynaptic soma (middle), $\sqrt{{(x_{pre}-x_{sp})}^2+z_{pre}{}^2}$; and the straight-line distance of the dendritic spine from the presynaptic soma (right), $\sqrt{{(x_{pre}-x_{sp})}^2+{(y_{pre}-y_{sp})}^2+z_{pre}{}^2}$. Black, blue, orange, and red bars indicate spines of sizes 0-0.1 μm³, 0.1-0.2 μm³, 0.2-0.3 μm³, and >0.3 μm³, respectively. *P < 0.05 (one-way ANOVA followed by Tukey's test). (D) Histograms of x_pre. Black, blue, orange, and red bars indicate the presynaptic cells innervating the spines of sizes 0-0.1 μm³, 0.1-0.2 μm³, 0.2-0.3 μm³ and >0.3 μm³, respectively. * P < 0.05 (Mann-Whitney U test).