Figure 5. Constrained optimization of the Na⁺ load of the squid axon model produces energy efficient action potentials.

(A) The action potential waveform before (light grey) and after (black) optimization. (B) The cumulative Na⁺ load during the action potential before (light grey) and after (black) optimization. (C) The Na⁺ (light grey, dashed line) and K⁺ (light grey, solid line) currents generating the action potential in the original squid giant axon model. Note the extensive overlap between the Na⁺ and K⁺ currents. (D) The Na⁺ (black, dashed line) and K⁺ (black, solid line) currents generating the action potential in the optimized squid giant axon model. Note the reduced overlap between the Na⁺ and K⁺ currents. (E) The changes in each of the biophysical parameters included in our constrained optimization after optimization relative to the original parameter values.