TABLE 2. Phasic and tonic second-order vestibular neurons
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| A. Parameters of action potentials |
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| Spike Threshold, mV | Spike Amplitude, mV | Spike Width, ms | Spike Rise Time, ms | Spike Fall Time, ms | AHP Amplitude, mV | |||||||
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| Phasic 2°VN | –55.3 ± 4.4 (175) | 58.9 ± 11.7 (175) | 1.8 ± 0.4 (175) | 0.8 ± 0.2 (175) | 1.0 ± 0.3 (175) | 9.7 ± 5.9 (175) | ||||||
| Tonic 2°VN | –55.6 ± 4.9 (48) | 56.5 ± 6.4 (48) | 1.7 ± 0.4 (48) | 0.8 ± 0.2 (48) | 0.9 ± 0.2 (48) | 13.0 ± 6.5* (48) | ||||||
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| B. Passive membrane properties |
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| Resting Membrane Potential, mV | Input Resistance, MΩ | Time Constant τ0, ms | Time Constant τ1, ms | |
| Phasic 2°VN | –69.7 ± 8.7 (194) | 13.9 ± 8.7 (133) | 2.1 ± 0.9 (133) | 19.6 ± 12.9 (133) |
| Electrically coupled | — | 10.0 ± 4.1 (17) | 2.0 ± 0.7 (17) | 19.5 ± 9.4 (17) |
| Not electrically coupled | — | 14.5 ± 8.0# (116) | 2.3 ± 0.9 (116) | 20.7 ± 12.2 (116) |
| Tonic 2°VN | –68.6 ± 9.9 (55) | 25.1 ± 17.1*** (27) | 2.0 ± 0.8 (27) | 24.7 ± 15.5* (27) |
| Electrically coupled | — | 12.9 ± 6.1 (8) | 1.7 ± 0.6 (8) | 14.3 ± 7.2 (8) |
| Not electrically coupled | — | 30.1 ± 14.5## (19) | 2.4 ± 0.8# (19) | 29.5 ± 13.6## (19) |
Phasic and tonic second-order vestibular neurons (2°VN) were subdivided according to the presence or absence of electrical
excitatory postsynaptic potentials (EPSPs) preceding the monosynaptic chemical EPSP. Parentheses enclose number of neurons;
significance of difference (Mann-Whitney U test) between phasic and tonic 2°VN:
* P ≤ 0.05;
*** P ≤ 0.0001; significance of difference (Mann-Whitney U test) between 2°VN that were electrically coupled or uncoupled:
# P ≤ 0.05;
## P ≤ 0.01.