Two-parameter diagrams for the change in maximal conductances and equilibrium potential.

<p>The hysteresis regions are shaded gray. A) Increase in <i>g</i>_K expands the oscillatory region, shortens the instability region and increases hysteresis in the DA neuron. B) Increase in K⁺ current reversal potential shortens oscillatory region much faster than the instability region, reducing hysteresis in the DA neuron. C) Increase in the maximum conductance of the leak current shortens both instability and oscillatory regions and finally eliminates oscillations in the DA neuron. D) Hysteresis exists in a narrow range of parameter <i>g</i>_K in the HH neuron. E) Hysteresis at the upper boundary of the oscillatory region is not affected by the decrease in E_K in the HH neuron. F) Hysteresis is slightly reduced with the decrease in the maximum leak conductance in the HH neuron. A–C) Parameter values from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042811#pone-0042811-g004" target="_blank">Figure 4B</a>. D–F) Parameter values from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042811#pone-0042811-g004" target="_blank">Figure 4D</a>. A solid curve represents an Andronov-Hopf bifurcation, a dashed curve – a saddle-node bifurcation of limit cycles. Horizontal dotted lines mark parameter values from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042811#pone-0042811-t001" target="_blank">Table 1</a> for the DA and the HH neurons, correspondingly.