The code provided is a representation of a computational model that simulates ion leak currents across a neuronal membrane, focusing specifically on sodium (Na⁺) and potassium (K⁺) ions. Here's a breakdown of the biological basis of the model: ### Biological Basis **Ion Channels and Membrane Potentials:** - Neurons communicate through electrical signals, and these signals are generated and propagated by ionic movement through specialized proteins called ion channels. - The ion channels allow the passage of specific ions (e.g., Na⁺ and K⁺) across the neuronal membrane, which is crucial for maintaining the resting membrane potential and generating action potentials. - The balance of ion concentrations inside and outside the neuron creates electrochemical gradients. **Leak Currents:** - The model simulates "leak" currents, which refer to the passive flow of ions through ion channels when the neuron is at rest. - These are not gated by voltage or ligand binding but allow a steady flow of ions based on their concentration gradients and membrane potential. **Reversal Potentials:** - The **reversal potential** (Nernst potential) for each ion (denoted as `ena` for Na⁺ and `ek` for K⁺) is critical for determining the driving force for ion flow. It represents the membrane potential at which there is no net flow of the ion through its channels. **Conductances:** - The **conductance** parameters (`gna` for Na⁺ and `gk` for K⁺) represent the permeability of the membrane to these ions. They are key factors determining the magnitude of the leak currents. - Biological conductance corresponds to the density and properties of the ion channels open at rest. **Model Objective:** - This model aims to replicate the ionic currents due to leak channels, which contribute to the stabilization of the resting membrane potential and influence the overall excitability of the neuron. - By capturing these passive ion flows, the model helps elucidate how neurons can maintain and regulate their baseline state between active signaling events. Overall, the model captures an essential physiological aspect of neurons: the movement of Na⁺ and K⁺ ions through channels that facilitate basic membrane potential dynamics crucial for neuronal function.