Table 2
Overview of membrane properties per cluster of SCN neurons
| Statistical significance | ||||||
|---|---|---|---|---|---|---|
|
|
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| Cluster I | Cluster II | Cluster III | I vs. II | I vs. III | II vs. III | |
| Distinguishing set of properties | Monophasic AHP | Biphasic AHP | Biphasic AHP | |||
| Irregular firing | Regular firing | Low-frequent or regular firing | ||||
| Small RD | Small RD | Large RD | ||||
| Number of cells | 52 | 21 | 9 | |||
| Resting membrane potential (mV) | −54.8 ± 0.5 | −55.3 ± 0.8 | −63.5 ± 1.8 | — | 0.0001 | 0.001 |
| Input resistance (GΩ) | 1.28 ± 0.06 | 1.41 ± 0.11 | 1.04 ± 0.08 | — | — | 0.05 |
| Time constant (ms) | 25.8 ± 1.4 | 33.8 ± 2.5 | 30.2 ± 3.7 | 0.01 | — | — |
| Action potential amplitude (mV) | 72.6 ± 1.6 | 73.9 ± 2.1 | 93.2 ± 4.7 | — | 0.001 | 0.001 |
| Action potential threshold (mV) | −40.2 ± 0.6 | −38.9 ± 1.2 | −42.8 ± 1.3 | — | — | — |
| Action potential width (ms) | 1.48 ± 0.05 | 1.43 ± 0.09 | 1.94 ± 0.18 | — | 0.05 | 0.05 |
| Amplitude of spike AHP (mV) | −21.9 ± 0.8 | −21.4 ± 1.2 | −17.5 ± 1.8 | — | — | — |
| Slope of spike AHP (mV ms−1) | 0.35 ± 0.04 | 0.01 ± 0.03 | −0.08 ± 0.15 | DP | 0.01 | — |
| Rate of frequency adaptation (ms s−1) | 29.8 ± 8.3 | 30.6 ± 5.7 | 374 ± 241 | — | 0.01 | 0.05 |
| Amplitude of spike train AHP (mV) | −6.7 ± 0.7 | −10.5 ± 0.9 | −3.3 ± 1.1 | 0.01 | — | 0.01 |
| Size of rebound depolarization (mV ms) | −4 ± 69 | 36 ± 115 | 1990 ± 181 | — | DP | DP |
| Spontaneous firing rate (Hz) | 2.9 ± 0.4 | 3.7 ± 0.6 | 1.1 ± 0.5 | — | 0.02 | 0.01 |
| CV of spike intervals | 0.41 ± 0.03 | 0.19 ± 0.04 | 0.31 ± 0.15 | DP | — | — |
| Percentage of cells with SPSPs | 88 | 76 | 78 | |||
| Percentage of cells with time- dependent rectification | 87 | 90 | 100 | |||
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For cluster I and II, regularity of firing refers to the range of firing rates between 1.5 and 5.0 Hz. RD, rebound depolarization. Parameter values represent means ±s.e.m. Recording conditions were the same as in Table 1, i.e. visually controlled whole cell patch clamp at 29–31 °C. Values in the 3 right-most columns indicate levels of statistical significance according to the Mann-Whitney U test. Student's t test indicated similar or smaller P values than the Mann-Whitney U test. For all distinguishing properties (DPs), P values were below 0.0001. SPSP, spontaneous postsynaptic potential.