Figure 4.

Computational modeling using morphological manipulations shows that AIS size (but not position) drives the firing rate. A, Firing rate observed when AISs from other reconstructed neurons replace the actual AIS (AIS in red, top diagrams), as a function of AIS length. B, Firing rate observed when a neuron's own AIS is grafted to random locations within the somatodendritic tree (arrowheads), as a function of AIS position. Black circles indicate presence of backpropagation failures (see Results and Fig. 9). C, Firing rate observed when artificially varying AIS length while keeping soma-to-AIS proximal border distance fixed. The top schematics show how lengths were varied. D, Firing rate observed when artificially varying soma-to-AIS proximal border distance while keeping AIS length fixed, as shown in the top schematics.