Figure 6.

The relative synchrony dependence of neurons changes with background conductance input. Aa, In a model neuron stimulated with constant excitatory conductance and randomly varying inhibitory conductance, spike responses are only weakly dependent on input synchrony, compared with input mean. Ab, Proportionately increasing the inhibitory and excitatory conductance inputs of the model neuron causes its output to become synchrony dependent. B, In a layer 5 bursting neuron, changing the synchrony of the current stimulus has little effect on spike output. C, Driving the same neuron in B with stronger artificial synaptic drive (i.e., proportionately scaling up the mean inhibitory and excitatory conductances) creates synchrony dependence in the spike output of the cell. Da, In n = 6 large bursting pyramidal neurons, adding artificial synaptic drive changed their response profiles from relatively synchrony independent to relatively synchrony dependent. Db, In n = 13 neurons, including G42, GIN, L2/3, and L5R neurons, scaling up the excitatory and inhibitory conductances that the neuron received increased its synchrony dependence, whether or not the response of the neuron was initially synchrony dependent. Neurons are color- and marker-coded as in Figures 3–5.