Figure 9.

Newly gained spines preferentially regrow at or nearby lost spines, or nearby existing spines, even in the absence of perturbation. A, Representative images showing the spine dynamics from one intact female mouse (d1–d3). The regrowth of lost spines was analyzed (red circles) with adjacent persistent spines (yellow circles) and new spines (white circles), with the persistent spines used as fiduciary points in all segments, to calculate spine loss and gain compared with d2. B, The cumulative probability curves compared the experimental regrowth probability of 55 dendritic segments from 5 intact mice (normalized to total gained spines), with the theoretical regrowth probability generated from a model of random spine addition; described in Materials and Methods. Left, Spine regrowth at the precise location where a spine was previously lost. Center, Spine regrowth nearby where a spine was previously lost. Right, Spine regrowth nearby existing spines (p < 0.001 for comparisons in all 3 panels, Kolmogorov–Smirnov two-sample test).