The discharge variability of neocortical neurons
during high-conductance states.
Michael Rudolph and Alain Destexhe
Neuroscience 119: 855-873, 2003.
In vivo recordings have shown that the discharge of cortical
neurons is often highly variable and can have statistics similar to
a Poisson process with a coefficient of variation around unity. To
investigate the determinants of this high variability, we analyzed
the spontaneous discharge of Hodgkin-Huxley type models of cortical
neurons, in which in vivo like synaptic background activity was
modeled by random release events at excitatory and inhibitory synapses.
By using compartmental models with active dendrites, or single
compartment models with fluctuating conductances and fluctuating
currents, we found that a high discharge variability was always
paralleled with a high-conductance state, while some active and
passive cellular properties had only a minor impact. Furthermore,
a balance between excitation and inhibition was not a necessary
condition for high discharge variability. We conclude that the
fluctuating high-conductance state caused by the ongoing activity
in the cortical network in vivo may be viewed as a natural
determinant of the highly variable discharges of these neurons.
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