The location of the axon initial segment affects the bandwidth of spike initiation dynamics
Fig 2
Performance of the “ball-and-stick” neuron model. Color-coding across panels reflects the soma-AIS distances, with darker colors used for more proximal AIS locations and brighter colors for more distal AIS locations. The somatic AP waveform was examined in time (A) and in the phase-space, plotting the derivative of the potential versus the potential (B). We conventionally set the AP “onset” to 10mV/ms (dashed horizontal black line), deriving the value of AP threshold (i.e. the potential at the onset) (C) and the AP rapidity (i.e. the phase slope at onset) (D). The magnitude of the dynamical transfer gain of the model was estimated as in Fig 1 and plotted in the Fourier domain, across increasing soma-AIS distances, normalized to its value at 1 cycle/s (E). The “cut-off” frequency, defined as the harmonic frequency corresponding to a 30% attenuation of the magnitude, was then studied against the soma-AIS distance (D) and fitted by a logistic function. Error bars (C-F) represent the standard deviation over 100 independent repeated simulations.
doi: https://doi.org/10.1371/journal.pcbi.1008087.g002