The provided code snippet is a part of a computational neuroscience model aimed at simulating neuronal activity, particularly focusing on the generation of action potentials and their propagation from the soma to the axon initial segment (AIS). These simulations are referenced in the context of a study by Michalikova et al. (2016). Let's break down the key biological aspects involved: ### Biological Basis of the Model 1. **Neuron Structure:** - **Soma and AIS:** The model emphasizes the soma (the neuron's cell body) and the AIS, a critical region where action potentials are initiated. The AIS is a specialized structure located near the axon hillock, playing a crucial role in integrating synaptic inputs and generating nerve impulses. 2. **Action Potential Propagation:** - **Spikelets, Shoulder Action Potentials (sh-APs), and Full-blown Action Potentials (fb-APs):** These terms refer to different forms of action potentials or variants in their initiation and propagation. They suggest varying levels of action potential threshold and morphology which could be influenced by distance and ionic currents. 3. **Parameter Variations:** - **Injected Current (`Iinj_list`):** The list of injected currents (`[1.3, 0.8, 0.5] nA`) represents varying amplitudes of input stimulation, likely simulating synaptic inputs or experimental current injections to elicit different neuronal firing responses. - **Distance to AIS (`L_hill`):** This parameter (`L_hill=100`) concerns the distance between the soma and the AIS, which affects the timing and likelihood of action potential generation. The `L_hill` parameter could affect the coupling between the soma and the AIS, thereby influencing how electrical signals are transmitted. 4. **Biophysical Properties:** - Although not explicitly defined in the code provided, typical models of this kind include biophysical parameters such as ion channel densities, gating variables (for ion channels like Na\(^+\), K\(^+\), etc.), and membrane capacitance, which define the electrical behavior of these neuronal compartments. ### Overall Objective The objective of the code is to simulate and visualize how action potentials are generated and propagate within a neuron, particularly focusing on the influence of neuronal microarchitecture (like the AIS distance) and inducing various firing patterns using different current injections. This could provide insights into neuronal signaling and its modulation under different physiological or pathological conditions.