Conventional measures of intrinsic excitability are poor estimators of neuronal activity under realistic synaptic inputs
Fig 4
Pharmacological blocking of the Kir- and D-currents produce differential effects in delayed vs. stuttering type neurons.
The voltage responses of a delayed firing type neuron are shown before (A) and after the application of BaCl2 (B). (C) Input-output functions obtained from the current step experiments indicate a moderate increase of the firing under BaCl2. (D) I-O relationship obtained from the dynamic clamp experiments. (E and F) Total spike counts in control and BaCl2-treated cells are shown for the current step vs. DCl experiments, respectively. (G) The average relative change in total spike counts in the current step (IV) and dynamic clamp (DCl) experiments. Panels (H-N) show the same for the stuttering type neurons under the application of 4-AP. The firing of the demonstrated neuron is markedly increased by 4-AP application when the current step stimulation is used (J) but increased to a less degree when the simulated synaptic inputs are used (K). The pooled data (L-M) reveal that spike counts under current step stimulation increase far more than firing under simulated synaptic inputs. (N) Average relative change of total spike counts following 4-AP application in the current step (IV) and dynamic clamp (DCl) experiments.