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

Model neocortical pyramidal neurons were investigated to evaluate the impact of correlated synaptic bombardment on cellular responsiveness. The responses to simulated glutamatergic (AMPA-mediated) excitatory inputs were analyzed by comparing correlated and uncorrelated background activity. Pyramidal cells behaved stochastically, consistent with the high variability of responses typically observed in vivo. Interestingly, the responsiveness was enhanced in the presence of correlated background activity, allowing the neuron to respond to inputs that would normally be subthreshold. We suggest that during active states, neocortical neurons should be described by stochastic equations which may better re#ect their behavior, compared to a deterministic description. ( 2000 Elsevier Science B.V. All rights reserved.