Figure 5
Differential intrinsic membrane properties between RS, IM and IB pyramidal cells. A-C, Plots of spike discharge frequencies for each interspike interval during the current injection illustrated in Figures 2F, 3F, 4F for RS, IM and IB cells. After the stimulating current reached spike threshold in each of the 3 representative cells, 3-4 current steps, each of 40 pA were applied. Note that at just above the rheobase, IB cell fired an initial burst with two APs at up to 50 Hz, whereas RS cell and IM cells fired APs regularly at ~5 Hz; D, Plots of the mean spike discharge frequencies, measured from the 1st interspike interval (left) and the last interspike interval (right) for RS (n = 20), IM (n = 36) and IB (n = 25) cells, at different stimulation intensities of depolarizing current (100--350 pA, 400 ms). In response to the same intensities of current RS generated spikes at the lowest frequency and degree of initial frequency moderately increased with increase in current intensity. IB generated an initial doublet of action potentials with highest frequency, which increased with increase in current intensity. The initial frequency of the spikes for IM was in between. Values are given as the mean ± S.E.M. *P < 0.05, significantly different from RS cells; **P < 0.01, significantly different from RS cells; ***P < 0.001, significantly different from RS cells; #P < 0.05, significantly different from IM cells; ###P < 0.001, significantly different from IM cells; two-way ANOVA. E, Histogram showing the distribution of the amplitude of the ADP. Black bars indicate the ADP of IB neurons (n = 14). Gray and white bars indicate the ADP of IM (n = 36) and RS (n = 20) neurons respectively. F, Histogram reflects the rheobase for RS (n = 20), IM (n = 36) and IB (n = 25) cells (**P < 0.01 based on one way ANOVA). Values are given as the mean ± SEM. (G) Histogram summary data of the half widths of the RS (n = 20), IM (n = 36) and IB (n = 25) cells (*P < 0.05 and **P < 0.01 based on one way ANOVA).