The provided code models the potassium (K\(^+\)) leakage current in a neuron. Potassium leakage current is an essential component of the neuronal membrane potential, contributing to the maintenance of the resting membrane potential and influencing the neuron's excitability. ### Biological Basis 1. **Ion Involved**: The code specifically models the flow of potassium ions (K\(^+\)) across the neuronal membrane. Potassium ions play a critical role in setting the resting membrane potential due to their high permeability compared to other ions at rest. 2. **Leak Currents**: Unlike voltage-gated ion channels that open in response to changes in membrane potential, leak channels allow ions to pass through the membrane at a constant rate. Potassium leak channels provide a steady conductance pathway, contributing continuously to the resting membrane potential. 3. **Nernst Potential**: The reversal potential for potassium (\(eK\)), which is the equilibrium potential where the net flow of K\(^+\) is zero, is set at -95 mV. This value reflects the typical concentration gradient of potassium ions across the neuronal membrane, with a higher concentration inside the neuron compared to the outside. 4. **Conductance**: The parameter `gbar` represents the maximum conductance of the leak channel per unit area. Conductance (\(S/cm^2\)) is crucial for determining how strongly the ion current influences the membrane potential. 5. **Leakage Current Equation**: The code calculates the potassium leakage current (\(i\) and \(ik\)) using Ohm’s law: \(i = gbar \times (v-eK)\), where \(v\) is the membrane potential. This linear relationship indicates that the driving force for K\(^+\) current flow is the difference between the membrane potential and the potassium reversal potential. By modeling the leakage current with these parameters, the code captures key elements of ionic dynamics that stabilize the neuronal resting potential. This is crucial for understanding how neurons maintain their baseline state and respond to synaptic inputs or other stimuli.