Figure 8. Stochastic ion channels modify synaptically driven spike output from a CA1 pyramidal neuron.

(A) Morphology of the simulated CA1 pyrmidal neurons (described in [44]), illustrating positions of recording electrodes placed on the soma (grey), apical (blue) and basal (red) dendrites. (B) Examples of membrane potential responses of the deterministic (red trace) and stochastic (black traces) versions of the model to distributed synaptic input. The summed synaptic current is shown in yellow. Letters and grey bars indicate times of action potentials highlighted in subsequent panels. (C) Spike rasters (top) for responses of the determinisitc model (red) and for 50 consecutive trials of the stochastic model (black) to the synaptic input pattern used in (B). Plotted below is the probability of somatic spike firing in 10 ms duration bins for the deterministic (red) and stochastic (black) versions of the model. (D–G) Examples of determinisitc responses (top row) and representative stochastic respones (lower two rows), illustrating “extra” somatic action potentials triggered by an “extra” actively propagating dendritic spike (D), “dropped” somatic action potentials resulting from failed dendritic depolarization (E–F), and an “extra” somatic action potental resulting from additional dendritic depolarizing potentials.