The code provided is a computational model designed to simulate certain aspects of neuronal behavior, specifically focusing on back-propagating action potentials in neurons. In this context, the model is biologically centered on the following key concepts: ### Neuronal Morphology and Regions - **Soma:** The cell body of the neuron, which serves as the primary site for electrical current injection in the simulation. The soma is responsible for integrating synaptic inputs and initiating action potentials. - **Dendrites:** The model includes specific arrays of dendrites such as apical and basal dendrites. Apical dendrites generally extend from the pyramidal neurons of the prefrontal cortex and are known to support back-propagation of action potentials. Basal dendrites emerge from the base of the soma and are involved in synaptic integration. ### Action Potentials and Back-Propagation - **Action Potentials:** These are electrical signals that travel along the neuron's axon, initiating at the soma and sometimes back-propagating into the dendrites. - **Back-Propagating Action Potentials (bAPs):** The model aims to capture the dynamics of bAPs, which are known to play roles in synaptic plasticity and signal integration in dendrites. ### Ionic Currents and Channels - **Calcium (Ca²⁺) Dynamics:** Calcium dynamics are considered through `cai` variables, showing interest in calcium currents (`icane` dynamics are also recorded). Calcium ions play critical roles in synaptic plasticity and triggering various cellular processes. - **Ionic Conductances:** The code simulates changes in specific conductances (`gCAN`, `ican`) which are potentially related to calcium-activated non-selective (CAN) cation currents and calcium dynamics in the neuron. ### Pharmacological Modulations - **Pharmacological Blockade:** The code includes procedures like `sadp()` to modulate or block certain ionic channels, aiming to simulate scenarios such as drug effects or genetic modifications affecting ion channels or synaptic activities. ### Simulation Setup - **Current Clamping:** The simulation includes mechanisms for injecting currents into neurons (current clamp) to artificially evoke action potentials and study their propagation through different dendritic regions. - **Recording Mechanisms:** Various regions such as the soma, specific points on apical dendrites, and basal dendrites are monitored to record voltage changes, highlighting how bAPs are reflected across different anatomical regions of the neuron. Overall, the code models the complex interplay of electrical and ionic dynamics within neurons, specifically focusing on capturing the phenomenon of back-propagating action potentials, which are important in neuron signaling and plasticity. This modeling provides insights into how neurons process information at the cellular level, particularly in the prefrontal cortex, where these phenomena have significant implications for cognitive functions such as learning and memory.