Cellular properties of intact and traumatized neurons
| Cellular Property | Intact | Intact Deep | Traumatized | Traumatized |
|---|---|---|---|---|
| Superficial | Superficial | Deep | ||
| Resting potential, mV | −72.7 ± 1.6 (19) | −67.0 ± 0.7 (72) | −73.6 ± 1.8 (19) | −66.6 ± 0.5 (110) |
| Time constant, msa | 7.2 ± 0.4 (14) | 7.1 ± 0.28 (65) | 7.2 ± 0.4 (19) | 7.2 ± 0.2 (110) |
| Input resistance, MΩb | 31.3 ± 2.8 (19) | 34.4 ± 1.4 (72) | 33.4 ± 2.2 (19) | 33.7 ± 1.4 (66) |
| % Overshootc | 9.7 ± 1.7 (7) | 24.2 ± 2.5 (17) | 6.5 ± 1.2 (8) | 25.4 ± 2.2 (17) |
| AP duration, msd | 1.56 ± 0.07 (13) | 1.26 ± 0.04 (32) | 1.43 ± 0.04 (15) | 1.23 ± 0.04 (35) |
| AP threshold, mV | −48.5 ± 1.3 (18) | −49.6 ± 0.7 (65) | −50.2 ± 1.2 (24) | −50.5 ± 0.6 (108) |
| F-I relation, Hz/nAe | 38.5 ± 2.0 (6) | 43.5 ± 2.5 (26) | 38.3 ± 3.9 (10) | 42.3 ± 1.9 (31) |
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Values are means ± SE with number of neurons in parentheses. AP, action potential; F-I, frequency-current. a Time constant obtained by fitting the membrane potential response to a −0.3 nA, 250 ms current injected into the cell at resting membrane potential using a single exponential function (y = A 0 + A 1e−t/τ, A 0 and A 1: offsets, τ: time constant). b Apparent steady-state input resistance calculated from the slope of the linear portion of the current-voltage relationship. c Percentage overshoot, i.e., the amount by which the membrane potential became transiently more positive than resting potentialfollowing a hyperpolarizing pulse (usually −0.5 nA), expressed as a percentage of the steady-state voltage deviation during the pulse (V overshoot/V steady-state ×100). The percentage overshoot was relatively constant regardless of the size of the current pulse. Data obtained limited to cells whose resting potentials ranged from −69 to −71 mV. d Action potential (AP) duration was obtained by measuring the width of the 1st spike at action potential half-amplitude. e Steady-state frequency-current relationship was estimated as the reciprocal of each interspike interval at a specified current injection. The frequency-current (F-I) relation was obtained by plotting the spike frequency as a function of current injection. The numbers here are the slopes of this F-I relation.