TABLE 1.Parameters of the recorded cells
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Interneurons
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Schaffer Input
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Alveus Input
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Pyramidal cells (Schaffer Input)
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n | 28 | 14 | 10 | |
Rin, MΩ | 116 ± 12 | 117 ± 14 | 95 ± 5 | |
τm, ms | 8.4 ± 0.9 | 9.3 ± 10.9 | 8.6 ± 0.6 | |
Firing rate, Hz | 23 ± 6 | 26 ± 9 | 4 ± 1* | |
AP width, ms | 1.3 ± 0.1 | 1.1 ± 0.1 | 1.7 ± 0.2* | |
Δt Schaffer input, ms | -0.9 ± 0.2 | 2.0 ± 0.3† | -0.3 ± 0.3‡ | |
n | 21 | 23 | 10 | |
Reference amplitude, pA | 135 ± 20 | 135 ± 36 | 219 ± 39* | |
10-90% rise time, ms | 2.7 ± 0.3 | 2.4 ± 0.6 | 2.7 ± 0.4 | |
Decay time constant, ms
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23 ± 4
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24 ± 3
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23 ± 3
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Top: cell parameters are given for interneurons receiving predominantly Schaffer or Alveus input and pyramidal cells. n is number of cells; Rin, input resistance; τm, membrane time constant. Firing rate was determined as the number of action potentials that the cell fired during 1 s of +200-pA current injection. AP width, width of action potential at half-maximal amplitude. Indicated are significant differences (P < 0.05; Student's t test) between interneurons and pyramidal cells (*). Δt Schaffer input - time difference between the peak of the population spike and the onset of synaptic input in the cells after Schaffer stimulation. After Schaffer stimulation, synaptic input to pyramidal cells occurred significantly later than monosynaptic input and significantly earlier than disynaptic input to interneurons (‡). Not surprisingly, monosynaptic input occurred significantly earlier than disynaptic input (†). Bottom: Parameters of synaptic currents for Schaffer and Alveus input to interneurons and Schaffer input to pyramidal cells used for analysis of the synaptic dynamics. The mean amplitude of the synaptic response to the first stimulus of the trains (the reference amplitude) was chosen to be ∼50% of the maximal amplitude that could be evoked by the stimulus (see RESULTS). In 9 interneurons, we measured the synaptic dynamics of both Schaffer and Alveus input. The cellular properties of these 9 cells were not different from the other interneurons.