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. Author manuscript; available in PMC: 2016 Jan 13.
Published in final edited form as: Cell Rep. 2014 Dec 31;10(2):162–169. doi: 10.1016/j.celrep.2014.12.016

Figure 1. Structural potentiation of multiple spines on a single dendritic segment induces structural depression of nearby unstimulated spines.

Figure 1

(A) Images of dendrites from EGFP-transfected CA1 neurons (13–18 DIV) exposed to high frequency uncaging (HFU; yellow crosses). A nearby unstimulated spine (filled red arrowheads) shrank following HFU-stimulation of multiple neighboring spines. In contrast, heterosynaptic shrinkage was not observed at an inactive spine (open red arrowheads) following shifted HFU stimulation.

(B) Structural potentiation of multiple neighboring spines (black bar; 31 cells, average 6 spines per cell; p < 0.01) decreased the size of nearby unstimulated spines compared with baseline (red bar; 31 spines; p < 0.01); in contrast, neither neighboring (open black bar; 15 cells, average 8 spines per cell; p = 0.1) nor unstimulated spines (open red bar, 15 spines; p = 0.3) showed changes in size following shifted HFU stimulation.

(C) Time-course of heterosynaptic spine shrinkage. Unstimulated spines inside the cluster (3.2 ± 0.6 μm from HFU stimulated spines; filled red circles; 31 spines) of stimulated neighbors shrank as compared to baseline (p < 0.01) or to distant unstimulated spines (≥ 10 μm from HFU stimulated spines; p < 0.05; blue asterisks) which did not shrink (open red circles; 12 spines; p > 0.3 at all post-HFU time points).

(D) Time-course of homosynaptic spine enlargement. Stimulated spines (black circles; 43 cells, average 6.3 ± 0.1 stimulated spines per cell) increased in size in response to HFU stimulation (p < 0.01 at all post-HFU time points).

(E) An inverse correlation was found between the magnitude of structural potentiation of stimulated spines (average of all stimulated spines) and the magnitude of shrinkage of inside cluster unstimulated spines on the same dendrites (31 cells; r = −0.49, p < 0.01).

(F) When HFU-induced structural potentiation of neighboring spines was successful (left black bar; 24 cells, p < 0.01), inside cluster unstimulated spines shrank (left red bar; p < 0.01); however, shrinkage of inside cluster unstimulated spines was not observed (right red bar; 7 cells, p = 0.49) when HFU did not lead to potentiation of neighboring spines (HFU failure, right black bar, p = 0.53).