Fig. 4: 16p11.2 deletion caused morphological changes and hyperexcitability of the DA neurons.
a Representative images of neurons loaded with Alexa Fluor 488 dye (1 µM) during recordings. Scale bar 25 µm. The experiment was repeated three independent times with similar results. b Characterization of soma size, number of primary neurites, and length of longest neurite of the patched cells. Soma area was significantly increased in the 16pdel cells compared to control cells (p = 0.0076). The number of primary neurites was significantly higher in the 16pdup cells compared to control cells (p = 0.0091). There was no statistical difference in the length of longest neurite between the cell groups studied, nonparametric Mann–Whitney test with two-tailed p values, **p < 0.01. The number of biologically independent samples for soma size and neurite number analyses are n = 29 control, n = 24 16pdup, and n = 21 16pdel. The number of biologically independent samples for neurite length analyses are n = 30 control, n = 22 16pdup, and n = 22 16pdel. Data are presented as mean ± SEM. c Left, representative traces of spontaneous action potentials (APs) at resting membrane (Vm) (Ihold = 0 pA) in the control, 16pdup, and 16pdel cells. Vm of representative current-clamp traces in 16pdel, control, and 16pdup neurons, −38, −39, and −37 mV, respectively. Scale bar 25 mV and 1 s. Right, representative current-clamp recordings demonstrate action potentials in response to current steps of (+15 and −5 pA). Scale bar 10 mV, 50 ms. d Excitability analyses of the DA neurons revealed minimum current input (pA) required to generate the first action potential was significantly lower in the 16pdel cells compared to control cells. For generating the input–output excitability curve, control, 16pdel, and 16pdup neurons were current clamped to a Vm potential of −60 mV. 16pdel neurons generated significantly higher number of action potentials compared to control cells or 16pdup cells, **p < 0.02 and ***p < 0.01. Data are presented as mean ± SEM. e Rheobase values (pA) for control, 16pdup, and 16pdel neurons show significantly lower Rheobase for 16pdel cells vs. control cells (p = 0.0126), and 16pdel vs. 16pdup cells (p = 0.0246), nonparametric Mann–Whitney test with two-tailed p values, *p < 0.05. The number of biologically independent samples are n = 24 control, n = 20 16pdup, and n = 16 16pdel. f Characterization of the number of APs generated by injection of a maximum current stimulation (50 pA) to control, 16pdup and 16pdel neurons. 16pdel neurons generated significantly higher number of APs compared to control cells (p = 0.028), parametric unpaired t test with Welch’s correction and one-tailed p value, *p < 0.05. The number of biologically independent samples are n = 11 control, n = 11 16pdup, and n = 12 16pdel. Data are presented as mean ± SEM (e, f). Source data are provided as a Source Data file.
