The provided code models a passive leak current, a fundamental component in computational neuronal models representing the passive electrical properties of a neuron's membrane. Here's an explanation of the biological basis:

Biological Basis

1. Leak Conductance:

   • The leak conductance represents ion channels that are always open, allowing ions to passively flow across the neuronal membrane. This flow is primarily driven by the electrochemical gradient.
   • The parameter glbar_inter denotes the maximum conductance (in siemens per square centimeter), a measure of how wide open the leak channels are supposed to be and, thus, how easily ions can flow through them.

2. Resting Membrane Potential:

   • The leak channels contribute to setting the resting membrane potential, the steady-state potential of the neuron when it is not actively firing. The parameter el is set to -75 mV, indicating the reversal potential for the leak current. This reversal potential typically approximates the resting membrane potential, determined by the distribution of ions across the membrane.

3. Membrane Potential:

   • Neurons maintain a difference in charge across their membranes, called the membrane potential (v). This potential is crucial for neural excitability and signaling.

4. Ion Flow and Current:

   • The code calculates the leak current (il) using Ohm's Law: ( I = g \cdot (V - E) ), where I is the current, g is the conductance, V is the membrane potential, and E is the reversal potential. In the model, this translates to ( il = glbar_inter \cdot (v - el) ).
   • The leak current represents the passive flow of ions (primarily potassium and sodium) that do not involve voltage-gated channels. It is a nonspecific current, meaning it is not selective for a particular ion type.

Importance in Neuronal Modeling

• Stabilizing Factor: The passive leak conductance stabilizes the resting potential and counteracts depolarization, helping the neuron maintain its resting state.
• Foundation for Action Potentials: This model component provides the baseline ionic conductance against which active processes, like action potential initiation, occur.
• Intracellular Signal Integration: Leak currents contribute to the neuron's ability to integrate incoming synaptic signals and thus play a role in neuronal computation and information processing.

By incorporating a leak current, this model captures essential aspects of neuronal behavior, allowing researchers to simulate electrical activity more accurately.