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Fig. 1 | Molecular Brain

Fig. 1

From: Burst firing is required for induction of Hebbian LTP at lateral perforant path to hippocampal granule cell synapses

Fig. 1

Intrinsic properties of regular-spiking (RS) and burst-spiking (BS) mature granule cells. A Representative voltage responses of RS (black) and BS (red) cells to somatic current injection of 250, 300 and 650 pA (1 s duration). Inset, initial firing of BS-GCs at expanded time scale. Initial firing frequency (Finit) was measured as the frequency of first two APs at rheobase current injection. B Bimodal distribution of Finit among mature GCs. Mature GCs were divided into RS and BS with the reference frequency of 50 Hz (RS/BS, n = 18/42). C, a, b Finit (a) and spike numbers (b) of RS and BS cells as a function of injected current amplitude (from 50 to 650 pA). Finit of RS cells increased steeply compared to that of BS-GCs. The general excitability of both GCs was not different throughout all steps (RS/BS, n = 18/22). D Summary bar graphs for analyses of 1st AP waveform evoked by somatic rheobase current injection into RS and BS cells. Mean values for AP threshold were − 34.9 ± 0.5 mV in RS and − 36.7 ± 0.7 mV in BS (*p < 0.05). For afterhyperpolarization (AHP) amplitudes, 17.1 ± 0.5 mV in RS and 12.0 ± 0.5 mV in BS (***p < 0.001). For half-width duration, 0.70 ± 0.01 ms in RS and 0.79 ± 0.01 ms in BS (***p < 0.001; RS/BS, n = 18/22). E Input resistance (Rin; RS, 116.1 ± 9.6 MΩ; BS, 115.3 ± 6.1 MΩ) and resting membrane potential (RMP; RS, − 82.1 ± 1.3 mV; BS, − 81.2 ± 0.9 mV) were not different between RS and BS. F Proportion of RS and BS cells depends on the GC maturity. BS cells were more frequently found in the group of mature GCs (Rin < 200 MΩ) compared to the less mature GC group (Rin ≥ 200 MΩ; RS/BS, n = 16/17). G Distributions (left) and mean values (right) for maximal dendritic branch order in RS (black) and BS (red) cells (RS, 4.5 ± 0.3, n = 8; BS, 5.1 ± 0.1, n = 18, p = 0.10). H Proportion of RS and BS cells along the dorsoventral axis (RS/BS in dorsal, n = 84/148; in ventral, n = 37/8). Error bars indicate S.E.M. *p < 0.05. ***p < 0.001. n.s., not significant (p > 0.05)

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