Dependence of EPSP Efficacy on Synapse Location in Neocortical Pyramidal Neurons Stephen R. Williams and Greg J. Stuart

Supplementary Material

Supplemental Figure 1. Uniformity of distal EPSP kinetics. A. Representative sEPSPs generated at distal dendritic sites and following spread to proximal recording loci. Spontaneous EPSPs are sub-averages in 0.4 mV bins, up to 2mV after which all large amplitude sEPSP were pooled. The inset shows peak-scaled sub-averaged sEPSPs to allow comparison of kinetics. B. Distributions of rise time and half-width of distal dendritic sEPSPs shown in A. The green lines represent probability density functions, showing the vast majority of sEPSPs have similar kinetics. C. Pooled data of distal dendritic sEPSP kinetics, obtained from sub-averages, like those shown in A. The green points show the mean (± SEM) values of rise and half-width. The line represents a linear regression. D. Distal dendritically generated sEPSPs can have a large local amplitude (recording 540 m from soma). E. Cumulative probability distributions of local distal sEPSP amplitude for five neurons.

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Supplemental Figure 2. Propagation of dendritic spikes to the soma. A. Triple recording of dendritic spike propagation evoked by near coincident (5 ms) aEPSPs. aEPSPs were generated at 660 m and recorded at the indicated sites. B. Somatic response to dendritic spike generation by aEPSPs (generated 620 m from the soma) during somatic hyperpolarisation to prevent initiation of axonal action potentials

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