Figure 5.
The local synaptic signal (ΔF/F)syn is governed by a variety of Ca2+ sources, including NMDA-Rs and VDCCs. A, Individual experiment in a responsive spine. Top, (ΔF/F)syn in the spine. Middle, (ΔF/F)syn in the adjacent dendrite. Black traces show averaged control responses (ctrl), and gray traces show those in 10 μm APV. Bottom, Scatter plot of local synaptic response amplitudes in spine versus dendrite. Black diamonds, Experiments under control conditions (similar to Fig. 2 E). Gray circles, Data in the presence of 10 μm APV. B, Individual experiment in responsive spine. Top, (ΔF/F)syn in the spine. Black traces show averaged control responses, gray traces show those in 10 μm APV, and black dashed traces show those in 10 μm APV and 100 μm Ni2+. The relatively large size of (ΔF/F)syn and its slow kinetics in this experiment were also observed in a few other GC spines. Bottom, Corresponding averaged EPSPs. C, Cumulative display of the effect of APV on (ΔF/F)syn (n = 9 spines), shown in absolute values (top) and as mean percentage change of control (gray bar, bottom). The effect of APV on EPSP amplitudes is also shown as mean percentage change of control (white bar, bottom). D, Display of five individual experiments showing the absolute effect of coapplied 10 μm APV and 100 μm Ni2+ on synaptic (ΔF/F)syn in spines, shown in absolute values (top) and as mean percentage change of control (gray bar, bottom). The effect of coapplied APV and Ni2+ on EPSP amplitudes is shown as mean percentage change of control (white bar, bottom).