Consequences of correlated synaptic bombardment on the responsiveness of neocortical pyramidal neurons

Model neocortical pyramidal neurons were investigated to evaluate the impac t of correlated synaptic bombardment on cellular responsiveness. The respon ses to simulated glutamatergic (AMPA-mediated) excitatory inputs were analy zed by comparing correlated and uncorrelated background activity. Pyramidal cells behaved stochastically, consistent with the high variability of resp onses typically observed in vivo. Interestingly, the responsiveness was enh anced in the presence of correlated background activity, allowing the neuro n to respond to inputs that would normally be subthreshold. We suggest that during active states, neocortical neurons should be described by stochasti c equations which may better reflect their behavior, compared to a determin istic description. (C) 2000 Elsevier Science B.V. All rights reserved.