Figure 5. Aβo-mediated plasticity impairment is locally restricted near sites of surface binding. A, left, Representative image of a dendritic segment from a neuron transfected with tdTomato (red) and treated with Aβo-488 (teal). Asterisks designate the location of MNI-glutamate uncaging. The closed arrowhead shows a spine with bound Aβo (Aβ+), and the open arrowhead shows a neighboring spine lacking Aβo (Aβ–). Right, Time course of Aβo– spine (top) and Aβo+ spine (bottom) from the same dendritic segment before the uncaging stimulus and up to 24 min following the stimulus. Scale bars: 5 μm (left panel) and 1 μm (right panels). B, Quantification of spine size (based on the cell fill intensity) before and after MNI-glutamate uncaging for control spines not treated with Aβo (blue, n = 14 spines, N = 5 neurons, 3 independent cultures), adjacent spines that were not stimulated (green, n = 12 spines, N = 5 neurons, 3 independent cultures), Aβ+ spines from cultures treated with 500 nm Aβo for at least 25 min (maroon, n = 16 spines, N = 8 neurons, 3 independent cultures), and neighboring Aβo-lacking spines (black, n = 14 spines, 8 neurons, 3 independent cultures). C, Average increase in spine cell fill signal during the final 3 min of imaging compared with baseline for control (n = 14 spines, N = 5 neurons, 3 independent cultures), Aβo+ (n = 16 spines, N = 8 neurons, 3 independent cultures), and Aβo– (n = 14 spines, 8 neurons, 3 independent cultures; *p ≤ 0.05, Student’s t test). ns = not significant. D, Average F/F0 over the final 3 min of imaging compared with baseline at Aβo-bound spines and neighboring Aβo-free spines on the same neurons (eight neurons, three independent cultures, *p = 0.0116, paired t test).