Intrinsic membrane properties of GAD67-GFP+ interneurons and hypoglossal motoneurons
Cell Type | n | Rn, mΩ | Tau, ms | C, pF | Sag-ratio | Vrest |
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A. Passive properties | ||||||
Interneurons | ||||||
Tonic, adapting | 17 | 888 ± 130 | 47 ± 5 | 62 ± 6 | 1.17 ± 0.05 | −69.0 ± 2.1 |
Tonic, nonadapting | 10 | 788 ± 146 | 57 ± 12 | 50 ± 7 | 1.30 ± 0.09 | −69.3 ± 2.0 |
Tonic, accelerating | 9 | 808 ± 81 | 47 ± 5 | 62 ± 7 | 1.13 ± 0.03 | −72.1 ± 2.7 |
Phasic | 7 | 375 ± 68† | 15 ± 3† | 42 ± 6 | 1.10 ± 0.02 | −68.3 ± 2.2 |
HMs | 7 | 57 ± 130* | 6 ± 1* | 117 ± 28* | 1.31 ± 0.08 | −75.4 ± 1.7 |
ANOVA, P value | <0.05 | <0.05 | <0.05 | >0.05 | >0.05 |
Cell Type | n | APth, mV | APh, ms | APhw, mV | AHP, mV | tAHP, ms |
---|---|---|---|---|---|---|
B. Action potential properties | ||||||
Interneurons | ||||||
Tonic, adapting | 17 | −51.6 ± 2.1 | 56.0 ± 4.0 | 1.76 ± 0.14 | −20.6 ± 0.8 | 44.5 ± 5.93 |
Tonic, nonadapting | 10 | −54.0 ± 1.4 | 58.7 ± 3.3 | 1.28 ± 0.10 | −22.3 ± 1.1 | 33.6 ± 2.7 |
Tonic, accelerating | 9 | −50.3 ± 2.5 | 59.3 ± 5.1 | 1.15 ± 0.08 | −23.1 ± 2.1 | 28.0 ± 3.6 |
Phasic | 7 | −52.2 ± 1.3 | 50.7 ± 2.6 | 1.39 ± 0.17 | −17.1 ± 2.0† | 11.0 ± 1.8† |
HMs | 7 | −54.3 ± 2.2 | 62.3 ± 4.9 | 0.81 ± 0.05* | −16.2 ± 1.4* | 9.5 ± 3.1* |
ANOVA, P value | >0.05 | >0.05 | <0.05 | <0.05 | <0.05 |
Cell Type | n | Adap-ratio | Ith, pA | fth, Hz | fI slope, Hz | fL slope, Hz |
---|---|---|---|---|---|---|
C. Firing properties | ||||||
Interneurons | ||||||
Tonic, adapting | 17 | 1.31 ± 0.04 | 22.5 ± 4.2 | 4.4 ± 0.5 | 9.5 ± 1.7 | 4.2 ± 0.8 |
Tonic, nonadapting | 10 | 1.01 ± 0.02 | 11.3 ± 1.7 | 5.0 ± 0.5 | 4.1 ± 0.6 | 2.8 ± 0.5 |
Tonic, accelerating | 9 | 0.83 ± 0.03 | 16.3 ± 3.4 | 4.9 ± 0.7 | 4.1 ± 0.3 | 3.6 ± 0.4 |
Phasic | 7 | NA | 42.9 ± 9.2† | 7.8 ± 2.3† | 12.8 ± 3.4 | 8.0 ± 1.9 |
HMs | 7 | 0.86 ± 0.10* | 367.9 ± 77.8* | 8.8 ± 1.2* | 15.3 ± 3.7* | 17.4 ± 3.3* |
ANOVA, P value | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 |
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Values are means ± SE. Rn, input resistance; tau, membrane time constant; C, total cell capacitance; Sag, sag-ratio calculated from: Vpeak/Vss (see methods); Vrest, resting membrane potential; APth, action potential threshold; APh, action potential height; APhw, action potential half-width; AHP, magnitude of the maximum spike afterhyperpolarization; tAHP, time to the peak spike afterhyperpolarization; Adap-ratio, frequency adaptation ratio calculated from the firing response to square current pulses (see methods); Ith, minimum or threshold current amplitude needed to elicit repetitive firing; fth, threshold frequency for repetitive firing; f1slope, slope of the relationship between the instantaneous frequency of the first spike interval in the train and the amplitude of the injected current pulse normalized by expressing current as a multiple of the threshold current (threshold current = 1); fL slope, slope of the normalized f–I relationship for the last spike interval in the train. ANOVA was performed between all five groups of cells. Significant differences between groups are discussed in the results.
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↵* Significant difference between interneurons and HMs (t-test, P < 0.05).
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↵† Significant difference between phasic and tonic interneurons (Tukey test, P < 0.05).