Membrane properties of STN neurons expressing different nAChRsa
| Parameters | No nAChRs | α7 nAChRs | α4β2 nAChRs | p | ||||
|---|---|---|---|---|---|---|---|---|
| n | Value | n | Value | n | Value | F(2) | ||
| Vm (mV) | 22 | -47.2 ± 1.4 | 20 | -47.1 ± 1.3 | 21 | -46.1 ± 1.1 | 0.2 | 0.83 |
| Rm (MΩ) | 22 | 863 ± 98 | 20 | 793 ± 65 | 19 | 908 ± 104 | 0.4 | 0.88 |
| Action potential | ||||||||
| Frequency (Hz) | 18 | 4.5 ± 0.7 | 18 | 6.6 ± 0.8 | 18 | 4.3 ± 0.7 | 3.0 | 0.06 |
| Half-width (ms) | 22 | 1.4 ± 0.1 | 20 | 1.1 ± 0.1 | 19 | 1.1 ± 0.1 | 1.97 | 0.14 |
| Variability | 22 | 0.26 ± 0.06 | 20 | 0.25 ± 0.03 | 19 | 0.20 ± 0.04 | 0.45 | 0.6 |
| AHP (mV) | 22 | -14.8 ± 0.6 | 20 | -17.8 ± 1.1 | 19 | -17.1 ± 0.8 | 3.6 | 0.03 |
| Hyperpolarizing response | ||||||||
| Voltage sag (mV) | 16 | 10.4 ± 1.6 | 14 | 9.5 ± 1.8 | 15 | 9.5 ± 1.2 | 0.13 | 0.82 |
| Rebound length (ms) | 19 | 447 ± 106 | 14 | 568 ± 87 | 13 | 331 ± 105 | 1.2 | 0.32 |
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↵aValues are mean ± SE. Vm, Membrane potential; Rm, membrane resistance; AHP, afterhyperpolarization. Firing variability is the ratio of SD to average of firing rate. To measure Rm, we applied a 5 mV hyperpolarization (0.5 s) from a holding potential of -50 mV, and Rm was calculated from Ohm's law. Voltage sag, transient component of the hyperpolarization in response to -80 pA current injection, caused by hyperpolarization-induced inward currents (Ih). In some neurons, a robust transient depolarization (rebound) occurred immediately after the end of the hyperpolarizing pulse. The duration of the depolarization is rebound length.