Fig 1. Pyr neurons maintain sensitivity to rapid input fluctuations over a wide range of depolarizing offsets.
(A) L5 Pyr neuron stained with biocytin. (B) Neurons were tested with a set of 5-second fluctuating currents of different mean μI (dashed black), and magnitude of input fluctuations, σI. (C) Typical response of a L5 Pyr neuron to a somatic injection of the current shown in panel B (μI = 0.27 nA, σI = 50 pA). (D) Steady-state firing rate f of a typical Pyr neuron as a function of the mean input μI (i.e., f−μI curve). Different lines indicate different levels of input fluctuations σI (see legend). For each combination of input parameters (μI, σI), three different 5-s current injections were performed. Firing rates were estimated during the last four seconds of the response. Error bars indicate one standard deviation across repetitions and are often too small to be visible. (E) Summary data obtained in different Pyr neurons (n = 6) by computing the percentage change in steady-state firing rate obtained by increasing the input standard deviation σI at the strongest μI used for each cell. Changes were computed with respect to σI = 0 pA. Each set of open circles represents data from a particular cell. Bar plots represent the mean and one standard deviation across cells. Increasing σI from 50 to 100 pA (n = 6, paired Student t-test, t = 4.4, p = 6.7 ⋅ 10−3) and from 100 to 150 pA (n = 6, paired Student t-test, t = 4.5, p = 6.5 ⋅ 10−3) significantly increased the firing rate.