The code provided is part of a computational neuroscience model aimed at simulating the electrical properties of specific types of mechanoreceptive sensory neurons. These neurons are responsible for tactile sensation and are located in the peripheral nervous system. The two procedures—`set_AbLTMR` and `set_CLTMR`—are configuring different types of mechanoreceptors, likely corresponding to Aβ low-threshold mechanoreceptors (AbLTMRs) and C low-threshold mechanoreceptors (CLTMRs). ### Key Biological Components 1. **Cell Morphology** - The parameters `soma.L` and `soma.diam` represent the soma length and diameter of the neurons, respectively. These morphological features influence the electrical properties, such as the input resistance and capacitance, by affecting the surface area-to-volume ratio. 2. **Ion Channels and Conductances** - **Nav Channels (`gnabar_nav1p1`, `gnabar_nav1p6`, `gnabar_nav1p7`, `gnabar_nav1p8`)**: These sodium (Na\(^+\)) channels are responsible for the rapid depolarization phase of the action potential. The variances in `gnabar` values reflect differing expression levels of sodium channels across neuron types, impacting excitability and firing patterns. - **Nav1.7 and Nav1.8** are frequently associated with sensory neurons and play significant roles in pain pathways and neuronal excitability. - **Kv Channels (`gkbar_kv1`, `gkbar_kv2`, `gkbar_kv3`, `gkbar_kv4`)**: These potassium (K\(^+\)) channels contribute to repolarization and setting the resting membrane potential. Variability in `gkbar` values also impacts the rate of repolarization and the overall action potential waveform. - Different types of Kv channels may correspond to different repolarization dynamics, which influence neuronal firing patterns. 3. **Leak Conductance (`g_leak`)** - Represents the basal permeability of the membrane to ions other than Na\(^+\) and K\(^+\). This passive ion current shapes the resting membrane potential and influences neuronal excitability. ### Biological Objective The model seeks to capture the distinct electrophysiological profiles of different mechanoreceptors. AbLTMRs are fast-conducting, myelinated fibers that typically carry fine touch and pressure sensations, whereas CLTMRs are unmyelinated or thinly myelinated fibers associated with gentle touch and temperature sensations. The specific ion channel configurations mimic the channel density and distribution observed in these neurons, providing insight into their functional roles in sensory processing. In sum, the code serves as a framework to explore how varied channel expression and conductance directly contribute to the distinctive firing patterns and sensory modalities of AbLTMR and CLTMR neurons, key components of tactile sensation.