  Correlated electrical activity in neurons is a prominent characteristic of
cortical microcircuits. Despite a growing amount of evidence concerning both
spike-count and subthreshold membrane potential pairwise correlations, little
is known about how different types of cortical neurons convert correlated
inputs into correlated outputs. We studied pyramidal neurons and two classes of
GABAergic interneurons of layer 5 in neocortical brain slices obtained from
rats of both sexes, and we stimulated them with biophysically realistic
correlated inputs, generated using dynamic clamp. We found that the
physiological differences between cell types manifested unique features in
their capacity to transfer correlated inputs. We used linear response theory
and computational modeling to gain clear insights into how cellular properties
determine both the gain and timescale of correlation transfer, thus tying
single-cell features with network interactions. Our results provide further
ground for the functionally distinct roles played by various types of neuronal
cells in the cortical microcircuit.
