Insect Muscle Activation Dynamics Simulator (IMADSim)

The package consists of an activation dynamics simulator (GUI) for five models (two non-linear and three linear) of insect muscle.

Included insect muscle activation dynamic models are from;
Non-linear models:
- Zakotnik et al., 2006
- Wilson et al., 2013
Linear models:
- Zajac, 1989
- Blumel et al., 2012
- Wilson et al., 2012

The GUI has five panels to select or set: the model, the corresponding model parameters, the motor neuron type, the spike shape and the spike generator. Arbitrary spike trains can be loaded from a .mat or .txt file consisting of spike times. For constant frequency spike trains, single or multiple spike frequencies can be set. The relaxation time may also be specified. There are three displays showing: the time course of isometric force generation, the corresponding spike train, and the model equations. Hold, Run and Reset buttons are used, respectively, to keep the multiple time courses on the display, run the simulation and to set the GUI to default values. Graphical outputs and the corresponding data can be saved to the workspace by selecting options in the toolbar. Tooltips or hints are provided when the mouse pointer hovers over an item in the GUI.

The optimisation routines are based on the Matlab LSQNONLIN solver for non-linear least squares problems. There are two main routines. The first is for both Zakotnik and Wilson non-linear models. The second is for the Zakotnik model only, and provides intermediate results (see below). When calling functions, several arguments can be set to customize the optimisation. Otherwise, default values will be used. The experimental data should be sampled at 5 kHz.

Experimental data (http://doi.org/10.4119/unibi/2937068) are also provided from six animals (female locusts, Schistocerca gregaria, hind-leg muscle responses for spike trains with different frequencies): three for the Slow Extensor Tibiae motor neuron (SETi) and three for the Fast Extensor Tibiae motor neuron (FETi). Corresponding optimisation results for the two non-linear models are provided.