edPR

edPR models electrodiffusive ion concentration dynamics in a multicompartmental extension of the Pinsky-Rinzel CA3 neuron model to maintain a biophysically consistent relationship between Na+, K+, Ca2+, and Cl- concentrations, electrical charge, and intra- and extracellular electrical potentials.

Key Features:

• Multicompartmental electrodiffusion: Extends the two-compartment Pinsky-Rinzel (PR) CA3 neuron framework to an electrodiffusive multicompartmental representation.
• Biophysical coupling: Enforces a biophysically consistent relationship between ion concentrations, electrical charge, and electrical potentials.
• Ion tracking: Explicitly tracks Na+, K+, Ca2+, and Cl- concentrations over time.
• Intra- and extracellular dynamics: Represents electrical potentials and conductivities in both intra- and extracellular spaces.
• Homeostatic mechanisms: Incorporates homeostatic processes and ion-specific leakage currents.
• Relaxes constant-concentration assumption: Removes the common assumption of fixed ion concentrations used in many neuronal models.
• Activity-dependent divergence from PR: Reproduces PR-like membrane dynamics under moderate firing but diverges when activity is high or homeostasis is impaired to capture concentration-driven effects.

Scientific Applications:

• Validation of modeling assumptions: Tests the validity of constant-ion and other simplifying assumptions across varying firing conditions.
• Dynamic ion concentration simulation: Supplements the PR model by simulating scenarios with time-varying Na+, K+, Ca2+, and Cl- concentrations.
• Pathological condition simulation: Models pathological states such as spreading depression and epilepsy where homeostatic mechanisms may fail.

Methodology:

Multicompartmental electrodiffusive modeling that extends the two-compartment Pinsky-Rinzel CA3 neuron model, tracking Na+, K+, Ca2+, and Cl- concentrations as well as intra- and extracellular electrical potentials and conductivities, and incorporating homeostatic mechanisms and ion-specific leakage currents to enforce biophysically consistent coupling between concentrations, charge, and potentials.