The provided code represents a computational model that simulates the bio-mechanics of whisker (vibrissa) movements in rodents. Whiskers are tactile sensory organs crucial for environmental exploration, spatial localization, and texture perception. This model specifically focuses on the dynamics involved when motor commands are applied to vibrissae, reflecting aspects like vibrissa rest angles, muscle forces, and damping influences. Key biological aspects present in the code: ### Whisker Configuration and Dynamics - **Whiskers in a Row:** The simulation considers a row of vibrissae with `N=5`, meaning five whiskers are studied for coordinated movement and interaction. Each whisker has a specified resting angle indicating its neutral position without muscle activation. - **Intrinsic Muscle Set:** Denoted by `intrinsic_muscle_set`, this vector specifies which whisker-associated muscles are active. Active muscles (represented with a `1`) influence whisker movement through contraction. ### Motor Commands and Muscle Dynamics - **Motor Neurons (`MN_spikes_times`):** The simulation includes a simplified spike timing to model motor neuron activity, inducing whisker movement by generating muscle contractions at specified time intervals. - **Force-Length Relationship (`force_factor`):** A key feature of muscle dynamics is the force-length relationship, governed by `fl_stat`. This dictates how the force generated by the muscles changes as the muscle length changes, influencing whisker's biomechanical response to motor commands. ### Biomechanical Parameters - **Mass and Inertia:** Parameters such as `Mh`, `Mf`, and `I0` (representing mass of the hair, mass of the follicle, and moment of inertia, respectively) are used to define the physical properties of whiskers and follicles that affect movement. - **Dampers and Springs (`zeta_up`, `zeta_dn`, `zeta_gr`, `Kup`, `Kdn`, `Kgr`):** These represent the viscous and elastic properties of the whisker base and surrounding tissue, which affect vibrational responses. Different directional components (vertical, upper, and lower) allow for realistic representation of how dampening and restoring forces act upon the whisker structure. ### Time Parameters - **Temporal Characteristics:** Simulation parameters like `tauc` and `taur` (activation and relaxation time constants) dictate the temporal dynamics of muscle force generation and relaxation, impacting how quickly whiskers respond to motor stimuli. ### Units Translation - **Conversion to MKS System:** The code includes conversion to standard SI units to ensure that simulation outputs could relate quantitatively to biological realities. This computational model provides insights into the temporospatial characteristics of whisker responses to motor commands, contributing to understanding the sensorimotor integration in tactile perception by rodents. The parameters reflect taxonomical definitions of whisker and muscle physiology, serving as a foundation for exploring how mechanical and neural factors converge to mediate sensory exploration with whiskers.