ReMoto - Simulation system of spinal cord motor nuclei

This project was developed by Rogerio R. L. Cisi and Andre F. Kohn, from the Biomedical Engineering Laboratory - University of Sao Paulo, Brazil, under the financing of FAPESP (Sao Paulo, Brazil). The paper describing the system is:

Cisi, R.R.L., Kohn, A. F. “Simulation system of spinal cord motor nuclei and associated nerves and muscles, in a web-based architecture”. Journal of Computational Neuroscience, 2008 [http://dx.doi.org/10.1007/s10827-008-0092-8].

The system is available for anyone to use it, provided a citation of the paper above is given in any publication that relies on results obtained from this simulator. Any suggestions for improvement are extremely welcome. Please contact: rcisi@leb.usp.br or andfkohn@leb.usp.br.

This site is best viewed with a resolution of 1280x1024 or 1024x768.

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## Download

The code of the system is available to those interested in expanding the system. The idea would be to keep expanding the system, while making it available to everyone. Click here to download the code.

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## Quick Overview

ReMoto is a Web-based neuronal simulation system, intended for studying spinal cord neuronal networks responsible for muscle control. These networks are subjected to descending drive, afferent drive and/or electrical stimulation. The simulator should be helpful in activities such as interpretation of results obtained from neurophysiological experiments in humans, proposal of hypotheses or testing models or theories on neuronal dynamics or neuronal network processing, validation of experimental protocols and teaching neurophysiology.

Stimuli can be applied to the neural circuits by appropriate selection in the configuration windows. Neuronal or synaptic properties can be modified to simulate normal or adverse conditions, mimicking real or idealized experiments. The human-machine interface is user-friendly.

The elements that take part in the system belong to the following classes: motoneurons, muscle fibers (electrical activity and force generation), Renshaw cells, Ia Inhibitory Interneuron, Ib Inhibitory Interneuron, Ia and Ib afferents. The neurons are interconnected by chemical synapses, which can be chosen to have depression.

The system simulates the following nuclei involved in flexion and extension of the human or cat ankle:

· Medial gastrocnemius (MG).

· Lateral gastrocnemius (LG).

· Soleus (SOL).

· Tibialis anterior (TA).

The figure below shows a general view of two antagonistic neural nuclei, in the so-called reciprocal inhibition pathway.

The next figure shows the inner structure of a neural nucleus. The motoneuron pool receives synaptic inputs from a few independent pathways: corticospinal, rubrospinal (excitatory and inhibitory) and Ia afferents. The user can select which type of MN will receive these inputs and calibrate the synaptic strength by altering the value of the default synaptic conductances. The RCs were associated with the nearest MNs and IaIn interneurons. Other inputs are also connected to the MN pool, as described in the Synapses window.

The default number of neurons for the human ankle flexor-extensor system is summarized below. Users can change these numbers, and chose how many nuclei will take part in a simulation.

| MN S | MN FR | MN FF | AF Ia | AF Ib
SOL | 800 | 50 | 50 | 400 | 200
MG | 250 | 125 | 125 | 80 | 40
LG | 200 | 100 | 100 | 76 | 38
TA | 250 | 50 | 50 | 280 | 140

| IN RC | IN IaIn | IN IbIn
# Flexion | 350 | 350 | 350
Extension | 350 | 350 | 350

This program is free software under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version.
A copy of the GNU General Public License can be obtained at http://www.gnu.org/licenses/.