Fig. 3: Long-day exposure increases intrinsic neuronal excitability.

a Representative traces of action potentials induced by current injection in neurons from 4LE, 12LE, and 20LE groups. Scale bar: 40 mV, 40 ms. b–d Summary data showing that 20LE, but not 4LE, increases intrinsic neuronal excitability compared to 12LE neurons at 2 dpl (b), 5 dpl (c), and 8 dpl (d). 2 dpl: n = 13, 17, 18; 5 dpl: n = 13, 12, 10; 8 dpl: n = 11, 9, 6 for 4LE, 12LE, and 20LE. MP: membrane potential. e–g Membrane capacitance (Cm), input resistance (Rin), and resting membrane potential (Vm) were not significantly altered among 4LE, 12LE, and 20LE-treated neurons at 2 dpl. 4LE/12LE/20LE: n = 18, 22, 15. *p < 0.05, **p < 0.01.