The name is absent

The cable equation describes the distribution of the membrane potential in space
and time if hyperpolarizing or depolarizing impulse is applied (Stoilov et al.,
1985). The time constant (τ) and the space constant (λ) have the meaning
respectively of time and distance for which the electric voltage V changes e~2,72
times.

The time constant depends on the membrane resistance that changes in time
because the channels do close and open. Dendritic membrane resistivity is
shown to be a sigmoidal function (Waldrop & Glantz, 1985). The time constant
depends on the channel conductances (Mayer & Vyklicky, 1989) and if directly
calculated we obtain wide range from 10ms to 100ms.

The space constant depends on the geometry of the neuronal projection and
particularly on its diameter. The space constantλ for dendrite with d=1μm is:

d RM   ∣10^-6m × 0.5Ω.m2

M = J-------------≈ 353μm

4 RA  V   4 × 1Ω m

Electric field in dendrites

Sayer et al. (1990) have measured the evoked excitatorypostsynapticpotentials
(EPSP) by single firing of the presynaptic terminal. In their study 71 unitary
EPSPs evoked in CA1 pyramidal neurons by activation of single CA3 pyramidal
neurons were recorded. The peak amplitudes of these EPSPs ranged from 0.03
to 0.665 mV with a mean of 0.131 mV. Recently it become clear that the remote
synapses produce higher EPSPs or in other words they ‘speak louder’ than the
proximal synapses so there is no sense to average the EPSPs (Spruston, 2000).
In the calculations done further in this paper we will consider that the single
EPSP magnitude is 0.2mV (London & Segev, 2001).

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