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Spatially Distributed Dendritic Resonance Selectively Filters Synaptic Input

Figure 2

Effect of boundary conditions on the spatial profile of resonance frequencies observed in a dendritic segment.

A. To explore the effect of boundary conditions on a dendritic segment, different resonant lumped boundary conditions, , are used. The color-code represents resonance frequency of the “lumped” boundary condition with blue to red corresponding to resonance frequencies ranging lower to higher than the cable characteristics –black line. B. A resonant boundary condition at the tip of a cable mimics sudden changes in membrane parameters and can represents as a first approximation either a change in channel density between segment of a in non-uniform cable or local geometric changes (branching or tapering). The influence of the resonant boundary condition is obtained analytically in the case of this simple abstract morphology. The spatial profile of resonance is shown for the different conditions presented in A. The spatial profile of resonance is influenced over its entire length in the case of short segments (75 µm -upper panel) while long segment (300 µm – lower panel) are affected mostly on their distal tip when compared to the refence case of a semi-infinite cable. C. Similarly, the spatial profile of resonance is drastically changed when a resonant boundary condition is located at the soma. The effect is large and observed over the entire resonant segment, even when the segment is long. This has important implication for e.g., stellate cells for which each dendritic branch “sees” at its proximal ending a resonant “lumped” boundary condition constituted of the soma and all other branches.

Figure 2