Supplementary Figure 2: 5-HT3AR+ interneurons receive direct MGB inputs.
From: Inhibitory circuit gating of auditory critical-period plasticity
(a) Layer (L) 1 interneurons and L4 pyramidal cells in primary auditory cortex (A1) show similar responses to medial geniculate body (MGB) stimulation. Left; Schematic illustrating recording configuration. L1 interneurons and L4 pyramidal cells were recorded during electrical stimulation of the MGB fibers. Right; Individual (gray) and mean (bolded) MGB-evoked EPSPs recorded in representative L1 late-spiking (LS) or non-LS cell subtypes and a L4 pyramidal cell. (b) Left; Mean (± SEM) EPSP amplitudes evoked by maximal MGB stimulation (EPSP maximum amplitude (mV): L1 LS = 7.34 ± 1.41, n = 7 cells/4 mice; L1 non-LS = 6.16 ± 2.14, n = 4 cells/4 mice; L4 = 7.33 ± 1.96, n = 11 cells/4 mice; Kruskal-Wallis test, χ2(2) = 0.47, P = 0.79). Right; Mean (± SEM) EPSP onset time, EPSP 10–90% rise time, and width at half maximum EPSP amplitude recorded in L1 interneurons and L4 pyramidal cells (onset time (ms): L1 = 11.36 ± 0.80, n = 11 cells/4 mice; L4 = 8.11 ± 0.84, n = 11 cells/4 mice; unpaired t test, two-tailed, t(20) = −2.80, P = 0.011, CL = −5.66, −0.83; rise time (ms): L1 = 8.18 ± 1.39, n = 11 cells/4 mice; L4 = 7.45 ± 1.35, n = 11 cells/4 mice; Mann-Whitney U test, two-tailed, z = −0.53, P = 0.599, CL = −3.13, 1.97; half-width (ms): L1 = 50.95 ± 4.96, n = 11 cells/4 mice; L4 = 57.64 ± 8.09, n = 11 cells/4 mice; Mann-Whitney U test, two-tailed, z = 0.33, P = 0.743, CL = −15.55, 32.66). (c) L1 interneurons and L4 pyramidal cells exhibit similar short-term depression of MGB-evoked EPSPs. Left; Schematic illustrating recording configuration. Trains of electrical stimuli were delivered to the MBG fibers during recordings in L1 interneurons or L4 pyramidal cells. Right; Mean (± SEM, shaded region) EPSPs recorded in all L1 interneurons (green, n = 8 cells/3 mice) and all L4 pyramidal cells (gray, n = 10 cells/3 mice) during repetitive electrical stimulation of the MGB fibers (10Hz). (d) Left; Mean (± SEM) EPSP amplitudes normalized to the first EPSP (EPSPN/EPSP1) evoked by each of 10 stimuli applied to the MGB fibers at 10 or 20Hz (L1, n = 8 cells/3 mice; L4, n = 10 cells/3 mice). Box indicates EPSP10/EPSP1. Right; Mean (± SEM) EPSP10/EPSP1 shows no significant differences between L1 interneurons and L4 pyramidal cells (10 Hz, L1 = 0.36 ± 0.06, L4 = 0.66 ± 0.18, z = −1.64, P = 0.10, CL = −0.06, 0.43; 20 Hz, L1 = 0.20 ± 0.04, L4 = 0.23 ± 0.04, z = −0.49, P = 0.63, CL = −0.11, 0.15, Mann-Whitney U tests, two-tailed, L1, n = 8 cells/3 mice; L4, n = 10 cells/3 mice). n.s. (not significant), P > 0.05; *P < 0.05.
