High discharge variability in neurons driven by current noise

Cortical neurons in vivo show a highly irregular spontaneous discharge activity, characterized by a gamma statistics and coefficient of variation around unity. Modelling studies showed that this irregularity is a consequence of the high-conductance state caused by the ongoing activity in the cortical network. Here, we investigate to which extent this high discharge variability can be reproduced in vitro using current noise injection. In agreement with numerical studies, we found that equalizing the time constant of the noisy input with the membrane time constant may lead to an irregular discharge activity which, however, departs from a gamma statistics. r 2004 Elsevier B.V. All rights reserved.