A novel method for characterizing synaptic noise in cortical neurons

Cortical neurons in vivo are subjected to intense synaptic noise that has a significant impact on various electrophysiological properties. Here we characterize the subthreshold activity of cortical neurons using an explicit solution of the passive membrane equation subject to independent inhibitory and excitatory conductance noise sources described by stochastic random-walk processes. The analytic expression for the membrane potential distribution can be used to estimate the average and variance of synaptic conductances from intracellular recordings obtained under current clamp. We demonstrate the application of this method to neuronal models of various complexity as well as to in vitro intracellular recordings.