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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 3. Heterosynaptic spine shrinkage requires close physical proximity to multiple potentiated spines.

Figure 3

(A) Shrinkage of unstimulated spines was not observed on those cells for which HFU led to structural potentiation (> 115% of baseline at 40 min) of less than four spines; in contrast, when four or more spines potentiated, unstimulated spines shrank (4 spines, p < 0.01; 5 spines, p < 0.05). Notably, an inverse correlation was found between the number of potentiated spines and the magnitude of shrinkage of unstimulated spines (31 cells, r = −0.49, p = 0.005).

(B) Images of a dendrite from an EGFP-transfected neuron exposed to one (top row) and three (bottom row) HFU (yellow crosses). Neither single nor triple HFU induced shrinkage of nearby unstimulated spines.

(C) Single (green bar; 25 cells; 1 spine per cell; p < 0.01) or triple (blue bar; 10 cells, 3 spines per cell; p < 0.01) HFU increased the size of stimulated spines; however, nearby unstimulated spines did not shrink (open green bar, 50 spines, p = 0.32; open blue bar, 10 spines, p = 0.17). Importantly, the magnitude of spine enlargement by single and triple HFU was indistinguishable (single, p = 0.56; triple, p = 0.81) from that observed to induce shrinkage of unstimulated spines (red bar; 11 cells, 6 spines per cell; p < 0.05).

(D) Images of dendrites from EGFP-transfected CA1 neurons exposed to multiple HFU stimuli (yellow crosses). An unstimulated spine located within the cluster of HFU-stimulated spines (filled red arrowheads) decreased in size; in contrast, neither unstimulated spines located outside, but directly adjacent to the HFU-stimulated cluster (top row), nor distant unstimulated spines (bottom row) shrank.

(E) Unstimulated spines located closest (2–3.4 μm) to and inside the HFU cluster decreased in size (red bar; 21 spines; p < 0.01); whereas those located inside the cluster but 3.4–4 μm from stimulated spines did not shrink (red bar; 9 spines; p = 0.19). Unstimulated spines located outside of the HFU-stimulated cluster did not shrink (3.4–4 μm, 6 spines, p = 0.62; 4–6 μm, 30 spines, p = 0.9; 6–8 μm, 23 spines, p = 0.89; 8–10 μm, 22 spines, p = 0.63; > 10 μm, 25 spines, p = 0.2). “inside unstim” data from Fig. 1B.