Figure 6.

Excitability and gain-scaling error in the G_Na versus G_K conductance plane. A, The biophysical model had three excitability regimes: silent, excitable, and spontaneously active (10,000 simulations, G_Na and G_K from 20 to 2000 pS/μm², in increments of 20 pS/μm²). To test excitability for nonspontaneously active neurons, the SD σ of a 10 s Gaussian noise current was increased in 2 pA increments until noise-driven hyperpolarizing voltage excursions became negative to −100 mV (silent) or the neuron fired an action potential (excitable). For LN models (Fig. 7), we used a coarser grid of conductance parameters (100–2000 pS/μm², in increments of 100 pS/μm²). B, D_σ was calculated for 148 model neurons with varying G_Na and G_K conductance values, stimulated with two stimulus SDs: σ₁ = 1 and σ₂ = 1.3 (Δσ = 30%). Warmer colors indicate larger gain-scaling error.