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Spatially Distributed Dendritic Resonance Selectively Filters Synaptic Input

Figure 4

Spatio-temporal input classicifcation in neurons due to to spatial profiles of resonance in the transfer impedance in dendrites.

A. Resonance frequencies of the transfer impedance. Each dendritic location is color-coded from blue (207 Hz) to red (247 Hz) and represents the resonance frequencies of the transfer impedance toward the soma (recording location). This demonstrates how non-uniform membrane parameters and a complex multi-polar cell morphology give rise to a large range of spatially segregated temporal filters. B. The spatio-temporal filtering ability of a stellate cell with distributed resonance properties. Two classification tasks are presented: one based on the temporal modulation of the input rate (B1) and one based on the spatial distribution of synapses (B2). In each case, the neuron receives 25 independent non-homogenous Poisson processes inputs. B1. Temporal selectivity: location of the (green) inputs are optimized so that the output spike rate best discriminates between two input signals; a target input signal modulated at 228 Hz and minimized for a null-signal modulated at 208 Hz. A schematic raster plot of the different input signal is shown (red: target signal, blue: null-signal). The target signal triggers many spikes (red trace) while the null-signal triggers none. B2. Spatial selectivity: synapses are inserted at dendritic locations matching a resonance frequency in the transfer impedance of 228 Hz (±4 Hz, red dots) or 208 Hz (±4 Hz, blue dots). When a signal modulated at 228 Hz is presented to the red group of synapses, the neuron responds with many spikes (red trace). When at the same red synapses a singal modulated at 208 Hz is presented, the neuron fails to respond and generates only a few spikes (blue trace).

Figure 4